©$?&>•.•# (kV •■'!'<, .-:-1. - ■n-BMiiiiI'fi; <';i-■ ~ -Tj 1 j -" 34*-*-^-:*< HBiBmnaiV'^^^^-- '''--^-:-:.- '-.-4 'TO J* i iO $ . I THE OPHTHALMOSCOPE; ITS THEORY AND Practical Uses. By C. H. VILAS, M. A., M. D., Professor of Diseases of the Eye and Ear in the Hahnemann Medical College, and Clinical Professor of Eye and Ear Diseases in the Hahnemann Hospi- tal, Chicago, Illinois. President of the Western Academy of Bomceopathy. Author of "A System of Eye and Ear Notes for Students;" of "Ocular Therapeutics;" of "Spectacles; and How to Choose Them," etc. CHICAGO: DUNCAN BROTHERS. 1832. y&i /, Entered according to Act of Congress, in the year 1880, by C. H. Vilas, M. D., in the Office of the Librarian of Congress, at Washington. PREFACE. This little volume is published to occupy a place hitherto vacant in medical literature, and supply a want which the Author has felt as a teacher. Much labor has been expended to make a book of practical value. The Author regrets that in his endeavor to be con- cise, omit all unnecessary diagrams, and abstain from rendering the volume hard to the novice, he is com- pelled to forego discussing the higher mathematics in- volved. With the single exception of the slight ref- erence under the subject of Ophthalmoscopic Optometry, and in the comparison of the direct and indirect meth- ods, he has made no allusion io them. The advanced practitioner and specialist, and many of his later pu- pils, will therefore miss that which the Author regrets to omit. 12 PREFACE. Inaccuracies in the details of some of the black-board diagrams are unavoidable. Mathematical precision must not be expected in rude sketches drawn to enable the reader to lay hold on points seemingly a little ob- scure. For his valuable aid, thanks are especially due to my assistant, C. F. Barker, M. D.; and to my house-phy- sician, C. A. Dewey, M. D., for his assistance in proof- reading. Chicago, November, 1881. CONTENTS. PAGE. Introduction,.........17 CHAPTER I. Reflection, Refraction, and the Formation of Images, • 22 CHAPTER II. Reflection, Refraction, and the Formation of Images, con- cluded, ..........30 CHAPTER III. The Theory of the Ophthalmoscope,.....38 CHAPTER IV. Description of Different Instruments, .... ^6 CHAPTER V. Description of Different Instruments, concluded, • • 56 14 CONTENTS. CHAPTER VI. PAGE. The Practical Application of the Ophthalmoscope, • • 67 CHAPTER VII. The Relative Value of the Direct and Indirect Methods, • 77 CHAPTER VIII. Examination of the Healthy Eye,......86 CHAPTER IX. Ophthalmoscopic Appearances in Disease and Malforma- tion, ...........92 CHAPTER X. Refractive Disorders,........101 CHAPTER XI. The Fundus of the Eye, 109 CONTENTS. 15 CHAPTER XII. PAGE. The Fundus of the Eye, continued,.....120 CHAPTER XIII. The Fundus of the Eye, concluded,.....132 CHAPTER XIV. Ophthalmoscopic Optometry,......139 THE OPHTHALMOSCOPEr ITS THEORY AND PRACTICAL USES. INTRODUCTION. The Ophthalmoscope is an instrument whose use per- mits of a thorough examination of the eye, without and within. This can be accomplished by no other device. In many respects its use is like that of the otoscope, or laryngoscope; it would be even more like these instruments, but for the fact that its successful use requires the harmonious adjustment of two compli- cated and separate dioptric systems, the eye of the patient and that of the examiner. Such is the case with no other diagnostic instrument; hence the diffi- culty so often met with by the novice. This fact, thoroughly comprehended, will serve to- 18 INTRODUCTION. eliminate all the discouraging- elements, and enable the practitioner, with a small amount of labor, to grasp the wonders which the Ophthalmoscope reveals. Previous to 1851, when Helmholtz published to the profession his invention of this instrument, beyond a few scattered observations, nothing had been evolved in the way of solving the problem of the illumination of the fundus of the eye. This had been due to the fact that it was believed that the choroid absorbed the rays of light reaching the fundus, and that none were returned. This error being practically refuted by this simple invention, a new era dawned in the progress of ophthalmic exploration. Not only was the special de- partment of ophthalmological practice revolutionized, but many other branches of the healing art had their resources augmented as well. Nearly all diseases of the eye posterior to the lens as now understood were either unknown, classed under amaurosis, or the subjects of mistaken conjecture. By one simple invention, the innermost and hitherto un- seen recesses of the eye were lighted up, and the oc- cult diseases placed within the range of the surgeon's vision. INTRODUCTION. 19 Science under the impetus of this master-mind swiftly swept away musty theories, and a new literature dis- placed the old. Those diseases of the fundus which had never been seen in the living subject, are no longer the vaunting ground of conceited ignorance, but the best understood, perhaps, of any lesions of the human economy. As the use of the instrument began to be known and appreciated in eye diseases, it was but natural that the phenomena here observed, should in time be associated with those occurring in more remote parts of the sys- tem. The results obtained have been most gratifying; for the ophthalmoscopic appearances of the fundus oculi are now recognized as important factors in the diagnosis of many diseases of the general system. In- deed if all is to be credited that has been written, there are few disorders in whose study and treatment, we may not bring the services of this instrument into requisition. That there are still great opportunities for discovery in this field of diagnosis, no one can doubt who is familiar with the present knowledge and recog- nizes the wide expanse unknown. But it is essential that he who would use the Oph- 20 INTRODUCTION. thalmoscope to good purpose must acquire, first, the knowledge of the optical principles of its construction ; second, dexterity in using the instrument, and third, the power of understanding the significance of what he sees. While the first may be easily overcome by a moderate amount of study, the mastery of the other two will depend greatly upon natural adaptation, and the perse- verance with which are made careful and repeated ob- servations and comparisons of facts. I will not dis- guise the fact that facility in the comprehensive use of this instrument is acquired only by patient, oft-repeated, careful effort; and he who would not stop short of the highest knowledge here, must as in all other valuable attainments, submit to the work inevitably precedino- it. No one who uses this instrument well has picked it up and quickly flashed it to the elucidation of hidden structures; he has patiently solved the problems pre- sented. An endeavor will be made in this little treatise to comprehensively place these problems before the reader without unnecessary difficulties in the way of their easy solution, pointing out the shoals whereon so many are INTRODUCTION. 21 stranded. The full understanding of all presented is necessary to a mastery of the instrument. Without it the practical attempts are like the wandering in the fabled maze—constant glimpses of an end never fully attained. CHAPTER I. REFLECTION, REFRACTION, AND THE FORMATION OF IM- AGES. When rays of light fall upon any surface, they are reflected, absorbed, or transmitted. Only a portion of light, however, which meets any surface is reflected; the remainder is absorbed or transmitted. Dense bodies and particularly those with smooth or light-colored sur- faces, reflect light most perfectly, and any surface which reflects light well is called a mirror. There are three general classes of mirrors known as plane, concave, and convex. It is more particularly with the concave mir- ror that we shall have to do. When light falls upon a plane reflecting surface, it is a well-known law that the angle of reflection is equal to the angle of incidence. If the reflecting surface be concave or convex, the same law holds good. The same law might be illustrated with either a coiir- cave or convex mirror. A mirror only changes the direction of the rays of light which fall upon it with- out altering their relative position ; that is if they fall upon it perpendicularly, they will be reflected perpen- dicularly ; if they fall upon it obliquely they will be ITS THEORY AND PRACTICAL USKS. 2.'> Fig. 1, In Fig. 1 let A B be the direction of the incident ray of light, falling on a mirror E F. It will be reflected in the direction B C. Let D B be perpendicular to the surface of the mirror at the point of reflection B, and it will be found that the angle of incidence A B D is equal to the angle of reflection C B D. 24: THE OPHTHALMOSCOPE; reflected obliquely; or as optically expressed, the angle of reflection is always equal to the angle of incidence. A concave mirror may be regarded as the interior surface of a portion or segment of a hollow sphere. When parallel rays of light fall upon the surface of a concave mirror, they are reflected and caused to con- verge to a point about half the length of the radius from the surface of the mirror. This point is called the principal focus of the mirror; and divergent rays issuing from it will be reflected parallel. Besides the principal focus a concave mirror has what are called conjugate foci. If the luminous point is at the center, the conjugate focus is at the center; if between the principal focus and the center, the conjugate focus is beyond the center; if beyond the center, the conjugate focus is between the principal focus and the center. The principal focus of a convex mirror lies as far behind the reflecting surface as in concave mirrors it lies before it. With such a mirror parallel rays are rendered divergent and no real focus is formed. It is only by producing the divergent rays by imaginary lines on the opposite side of the mirror, that the prin- cipal focus is found. The focus in this case is called the virtual focus, because it is only an imaginary point toward which the rays of reflection appear to be directed. The terms negative and virtual are applied to the focus ITS THEORY AND PRACTICAL USKS. 25 of the convex mirror in contradistinction to the focus of the concave mirror which is positive and real. Rays of light proceeding from several points of an object form what is known as an image. The images formed in a common looking-glass are mainly pro- duced by the reflection of rays of light from the metal- lic surface attached to the back of the glass, and not from the glass itself. We always seem to see an object in the direction from which the rays enter the eye; a mirror therefore, which changes the direction of the rays proceeding from an object, will change the apparent place of the object. Images are formed at the foci of concave mir- rors, and by varying the distance of the objects before the surface of the mirror, Ave may also vary the posi- tion and size of the images formed at such foci. AVhen an object is farther from the surface of a concave mir- ror than its principal focus, the image will appear inverted; but when the object is between the mirror and its principal focus, the imago will be upright, behind the mirror, and increased in size in proportion as the object is placed nearer to the focus. Let us now briefly consider what is meant by refrac- tion. Light, in a perfectly uniform transparent medium, traverses a straight line; but when light passes 26 THE OPHTHALMOSCOPE; obliquely from one medium into another, or from one part of the same medium into another part of different density, it is bent from a straight line, or refracted. A ray of light falling perpendicularly upon a surface separating two media continues in its original course. When light passes obliquely from a rarer to denser medium, it is refracted toward a perpendicular to the surface; but when light passes obliquely from a den- ser to a rarer medium, it is refracted away from a per- pendicular to the surface. The amount of refraction varies with the medium and the obliquity of the rays. No law has been discovered to enable us to judge of the refractive power of bodies by their other qualities, but as a general rule, dense bodies have a greater refractive power than those which are rare; but it may be well to mention that all highly inflammable bodies such as oils, diamond, phosphorus, amber, etc., have a refractive power many times greater than that possessed by non-inflammable substances of equal den- sity. When a ray of light passes through a transparent medium whose sides where the ray enters and emerges are parallel, it will suffer no permanent change of direction or refraction, since the second surface equally compensates for the refractive effect of the first; but if the surfaces of the medium are not parallel, the direc- ITS THEORY AND PRACTICAL USES. 27 tion of the ray passing through is permanently altered; and the change is greater as the inclination of the two surfaces is greater. Such is the case when light passes through a prism. Rays of moderate obliquity are refracted toward the base of a prism. This last fact is important, for by it the laws of refraction by curved surfaces can be better understood. Fig. 2. Place tAvo prisms base to base, (Fig. 2,) then any two parallel rays E E falling upon the surfaces at cor- responding points Avill be equally refracted toAvard the base, and will necessarily meet and cross at some point C situated on the opposite side. This point is termed the focus of the rays. Precisely this same thing Avould occur if the surfaces of the prisms Avere equally curved from center to edge, for all curved surfaces are composed of small plane surfaces arranged in a regular order correspond- ing to the curvature. A double convex lens may be regarded as tAvo prisms Avith curved surfaces, united at their bases. When the surfaces of a double or bi-con- :28 the ophthalmoscope; Fig, 6. (Fi°\ 3). A straight line passing through the cen- ter of a bi-convex lens and perpendicular to both sur- faces, is called the principal axis. Oblique lines pas- sing through the center are called secondary axes. ITS THEORY AND PRACTICAL USES. 29' vex lens are segments of a sphere, the lens is called spherical. All rays of light except those corresponding Avith principal and secondary axes, are refracted. Parallel rays are brought to a focus in a point on the axis to which they are parallel, and the focus of such rays is called the principal focus. The principal focal distance is the distance of the principal focus from the optical center of the lens. For the sake of brevity, this is often called the focal distance, or focal length, of the- lens. CHAPTER II. REFLECTION, REFRACTION, AND THE FORMATION OF IM- AGES, (concluded). Diverging rays from aluminous point situated at the principal focus are made parallel on passing through the lens; but rays from a more distant point being less divero-ent, are rendered convergent. The distance of the luminous point will determine the degree of the convergence of the rays, and as Avell, the distance from the lens of the focus in which the rays meet. The closer the luminous point approaches the princi- pal focus, the farther will the focus of the rays recede from the lens. If the luminous point is carried betAveen the lens and its principal focus, the rays after passing through Avill still be divergent, and no real or positive focus be formed. Since convex lenses collect and concentrate diverging rays of light at a point called the focus, they conse- quently produce increased light and heat at this point. In like manner concave mirrors by causing divergent rays to become convergent, produce the same effect. But the chief use of lenses is to produce images, and Q < In] Fig. 4 let L be the luminous point and K the £ principal focus of the lens. The diverging rays from § L meet in D. The nearer L approaches K, the farther h D will recede and vice versa. Place L at K, and the g rays from it Avill emerge from the lens parallel. The points L and D bear a constant relationship to each other, and are interchangeable; they are therefore termed conjugate. They are both real and positive. o I Fig, 5. ^ 111 Fig. 5, L is the luminous point, while K is the g principal focus. If the lines C C be produced back- I ward, they will meet in D and would have the same 8 optical value as if they really came from D instead of H L. D is the conjugate focus of the luminous point L, but as it has no actual existence, it is virtual and nega- tive. ITS THEORY AND PRACTICAL USES. 33 images are formed in the foci of convex lenses in the same Avay as in the foci of concave mirrors. Convex lenses magnify the apparent size of objects seen through them. The reason for this is plain ; for the lenses change- by refraction the direction of the rays of light proceed- ing from an object, and they enter the eye as if they came from points more distant from each other than is actually the case. This and other allied points Avill be made plain by a study of Figs. (> and 7. The distance at which a lens is held from an object modifies the size and the position of the image formed. This is demonstrated in Fig. 8. With a convex lens of two or three inches focus one can easily illustrate the truth of the statements in Fig. 8. It should be remembered, hoAvever, that Avhile the lens is at more than its principal focal length from the object, the inverted image is on his own side of the lens. It Avill appear to be upon the back of the lens. This inverted aerial image is constantly used in oph- thalmoscopy. Its careful study and thorough compre- hension is essential to the practical mastery of the in- direct method. 6i FlU. b. (Fig. (>). Hold the convex lens E F at less than its principal focal length from the object V B, and upon looking through the lens the enlarged image C D will be scon. The rays from the point A emerge from the lens divergent and have the optical value of coming from C). In like manner, vnys from B appear to come from 1). Fig. 7 shows how concave lenses produce a contrary effect, diminishing the apparent size of objects seen through them. Rays of light from the object A B on passim*-through the double concave lens C D are lefracted outward. If reproduced backward, they would come apparently from the direction of EF, or from points nearer together than is actually the case. To the ohserver look- ing through the lens, the apparent size of the object is diminished. 33 * THE OPHTHALMOSCOPE; 111 Fig. 8 let A B represent an object beyond the principal focus of the lens C D. Tracing all the rays which pass through the lens from the point A, we find them uniting at F on the secondary axis A H F. All the rays from B which pass through the lens unite at E on the secondary axis B H E. In like manner each point in the surface of A B looking toward the lens, has its corresponding point imaged in E F, and E F is the inverted, diminished image of A B. E is the con- jugate focus of B, and F is the conjugate focus of A; and varying the distance of A B from the lens will cause these foci to advance or recede. It is only when the object is at a distance of more than double the focal length of the lens, that the image is diminished beloAV the size of the object, and the diminution is greater as the object is carried farther away. If the object is held ITS THEORY AND PRACTICAL USES. 37 at just double the focal distance of the lens, the image Avill be at the same distance from the lens as the object and of the same size. Bring the object nearer and the image recedes and increases in size until the object leaches the principal focus, when the image disappears. The image disappears because the rays emerge from the lens parallel, thus producing diffuse light. Carry the object Avithin the principal focus, and the emergent rays Avill be divergent. If these rays are traced back- Avard, they form a negative focus on the same side of the lens as the object. Hence there is iioav produced an erect, virtual, magnified image of the object in the position of the negative focus. CHAPTER III. THE THEORY OF THE OPHTHALMOSCOPE. The eye itself is an optical instrument in which he refractive media combined are about equal to a convex lens of one inch focus. By means of these media, im- ages of external objects are formed upon the retina in an inverted position. In a normal and healthy eye, images of objects at various distances are distinctly focussed upon the retina, although it is evident such avouUI not be the case Avithout some change in the re- fractive poAver of the media. A change takes place Avhich is called the accommodation of the eye. By its accommodative power, the eye adjusts itself involuntarily for perception of objects at distances varying from a feAv inches to about eighteen to twenty feet, Avhich is regarded as infinity. Divergent rays from near objects and parallel rays from distant objects,. arc just as accurately focussed by a simple change in the focal distance of the lens, (in a manner as yet in some obscurity, different theories being advanced and seemingly Avell sustained by their authors), in conjunc- tion with other changes not necessary to consider here. As has been stated in the introduction, it Avas form- ITS THEORY AND PRACTICAL USES. 39^ erly believed that rays of light entering the eye reached the fundus and were there absorbed by the pigment layer of the choroid; hence no rays Avere reflected out- Avard through the pupil to convey to the eye of the ob- server an imasfe of the interior. This belief seemed confirmed by the black appearance of the pupil. The reason for such a mistake Avas due to the fact that rays of light projected into the eye are returned to the point whence they came. By means of the refractive media, the ingoing and outcoming rays form a cone of light whose base is at the pupil, and Avhose apex is at the source of illumination. This cone of fight is noAvhcre wider than the pupil and diminishes in width as the distance from the pupil increases. It is therefore evi- dent that any attempt of the observer to place his head- so as to receive the emergent rays within his oavii pupil, would cut off the Avhole source of illumination ; for the Avidth betAveen the observer's pupil and the temporal side of the head is much greater than that of the cone of light at any point. By the simple contrivance shown in Fig. 9, the diffi- culty is overcome. This cut correctly illustrates the original contrivance of Helmholtz, the discoverer of the Ophthalmoscope, except that the plane C D was of solid superimposed plates of glass. A plane mirror, C D, receives the rays of light from. 40 1HE OPHTHALMOSCOPE; no o. the luminous point A, and reflects a portion of them through the pupil of the eye under observation. They are focussed at B on the retina, andbeing reflected out- Avard again, a portion passes through the hole in the mirror in the direction of E. This is a simple form of the Ophthalmoscope, and the eye of the observer at the sight hole behind the mirror receives the rays from the fundus. ITS THEORY AND PRACTICAL USES. 41 The emergent rays from the fundus are generally slightly c« mvcrgent. They may be rendered parallel by either placing behind the mirror a concave lens, Avith Avhich all instruments are supplied, or by requiring the patient to look at a distant object, the latter way being used as experience permits. By looking at a distant object, the eye is accommo- dated for parallel incident rays, hence the emergent rays being equally retracted become parallel. Parallel rays are better adapted to the formation of distinct images upon the retina of the observer. Ordinarily the concave mirror is preferred to the plane. By concentrating the incident rnys, it not only reflects more light into the eye, but as the rays are con- vergent Avhen they enter, they are brought to a focus before reaching the retina, and as a result cross each other and form circles of dispersion. A larger portion of the fun dus is thereby lighted up at one time. In Fiij. 10 Ave have a diagram illustrating Avhat is known as the direct method of using the Ophthalmo- scope, or examination with the plane or concave mir- ror alone. A is the source of illumination, from Avhich rays im- pinge upon the con-care mirror with its sight-hole B. They are thence turned into the eye. L^t cc represent the circle of dispersion formed on the retina by the rays crossing in the vitreous humor. The return divergent 42 THE OPIITII ilmoscope; ITS THEORY AND PRACTICAL USES. 43: rays from any point t would emerge parallel and have the value of rays coming from the direction ee at points behind the eye, and from any point s the value of rays- from dd; hence the eye of the observer placed at B sees an enlarged, erect, virtual image situated appar- ently behind the eye observed. It will be seen that this form of the Ophthalmoscope- is very simple and consists in substituting reflected light for direct light, and in taking advantage of the return rays Avhich pierce the hole in the mirror. In Fisr. 11, is shown Avhat is known as the indirect method of examination, consisting in interposing the- double convex lens A, of from two to four inches focus,, and holding it near to the eye to be explored. This lens renders the rays from.the mirror more con- vergent and they are again converged by the crystalline- lens of the eye and form very large circles of dispersion upon the retina; thus a large portion of the eye is lighted up. Again, the rays emerging from the eye are brought to a focus between the interposed lens and the- mirror, and form a Avell-dcfined inverted image in the air. The size of this image depends upon the focal length of the lens; the greater the focal length, the- larger the image. The lens B behind the mirror is used to magnify the inverted image. Other lenses may- also be used behind the mirror, if the eye of the ob- server is not emmetropic. The lens B should have- about eight or ten inches focal distance. ITS THEORY AND PRACTICAL USES. 45 Embraced within these two methods Avill be found all the optical problems which have been considered heretofore. If clearly understood, the remainder of the subject is readily grasped; but if any point be dim, the reader is recommended to go back and rectify the- error before proceeding farther. CHAPTER IV. DESCRIPTION OF DIFFERENT INSTRUMENTS. There are many modifications of the Ophthalmoscope -devised by ingenious brains to develop and clear up the «ecming difficulties, but all involve the same principle. An examination of their mechanism Avith a careful study of their advantages Avill render the modes of use •quite plain, and familiarize the examiner Avith the de- tails of the practical principles involved. This, how- -ever, will not be attempted here, but those of Knapp, and Loring, of NeAv York, be considered, as being not only those most likely to be used, but as the best with which I am acquainted. Although by the inventor considered as not to be so highly recommended as his single-disc instrument, Ivnapp's double-disc Ophthalmoscope so clearly illus- trates the principles upon Avhich the instruments using the disc of Eckoss, (the revolving disc carrying the -little lenses), are constructed, that a carefully compiled nummary of it Avill be given as typical of the mechanism of the rest. It is taken from the inventor's description an the Archives of Ophthalmology and Otology. ITS THEORY AND PRACTICAL USES. 47 SHARP A SMITH. ¥mWM Jp' H mm 111 1 w Fie Hi. 48 the ophthalmoscope; Fig. 12 shows .the front view, and Fig. 13 the back view Avith the cover removed and placed to the right side. "Its reflector in the ordinary concave mirror, as in Liebreich's and other instruments. It is screwed on a thin plate of metal. On the other side of the metal plate lie tAvo discs, ol which the upper contains the convex lenses, 2, 3, 4, 6, 8, 10, 12, 14, 17, 20, 24, 33, 48, and the lower a like series of concave lenses. " Each disc rotates on a central pivot, and presses upon a delicate spring having at its end a small point- like elevation. Oppposite each lens is a point-like de- pression, into which the spring falls when the disc is rotated. These depressions are not so deep, however, as to prevent the disc from being easily turned, yet deep enough to cause the arrest of the disc when the center of the auxiliary lens through Avhich we Avant to look, is just opposite the center of the aperture in the mirror. "The margin of the lower disc overlaps the margin of the upper in such a Avay that each positive glass can be covered by each negative glass, and the reverse. Thus combinations are formed which enable us to ob- tain a very extensive series of test-glasses. " The rotation of the discs is very easy. When the instrument is closed, the margin of the upper disc pro- ITS THEORY AND PRACTICAL USES. 49 jects over the upper edge of the metal plates, Avhereas the margin of the lower disc projects on both sides OA'er the lower end of the plates. Each disk can be rotated to the right or left by a slight touch of the finger. This arrangement enables us to change the glasses without removing the instrument from the eye. " The lower disc is rotated with the forefinge of the hand which holds the instrument, Avhereas the upper disc is turned Avith the forefinger of the other hand. " The cover has three round apertures. The larger ■central one is opposite the aperture in the reflector, and serves for the passage of rays of light from the eye examined into that of the physician. The correcting lenses, when used, lie between this central aperture of the cover and the aperture of the reflector. In order to know Avhat lenses are used, two smaller round open- ings are placed one above the other, below the central aperture of the cover. Through these smaller aper- tures we read the numbers of the auxiliary lenses Avhich are behind the opening in the mirror. Whether these lenses are positive or negative, is indicated by the plus and minus signs placed near the smaller apertures. "A short ivory handle screws into a brass socket fastened to the mirror, and two larger lenses (plus 2 and 3, or other numbers according to the pleasure of the physician) are added. 4 50 THE OPHTHALMOSCOPE " Commonly the examination is begun without any auxiliary glass, namely for the investigation of the refracting media. After that the fundus is explored in the inverted image. Nearsighted observers do this without an auxiliary glass, but emmetropic, presby- opic and hyperopic observers are in the best optical conditions by placing a convex glass behind the mirror, thus rendering themselves artificially myopic, which should be of the degree of about 1-8 or 1-10 the ordi- nary visual distance for looking at fine objects. I have always been in the habit of placing plus 10 behind the mirror, and using plus 3 as the objective lens. This is a very convenient combination and magnifies the in- verted image to about three-quarters of the diameter of the erect image." The various auxiliary lenses represented in each disc are made to subserve two chief ends, viz., the deter- mination of ametropia by the objective method, and the measurement of elevations and depressions in the fundus of the eye. The first is fully considered under myopia, hypermetropia,* etc.; the method of calculat- ing the latter will be given in the chapter on Ophthal- moscopic Optometry (XIV.) If the observer himself is ametropic, he is recom- * The ascertaining of ametropia by the subjective method, or by the use of " trial- " or test-glasses," is fully expounded in the author's monograph on ''Spectacles; and How to Choose Them." ITS THEORY AND PRACTICAL USES. 51 Fig. 14. mended to have the lens which corrects his ametropia inserted in each disc, unless one disc already contains a 535323482353234823482348482353485348534853535323530002010200000102020201535323535353485353 ITS THEORY AND PRACTICAL I SES. 53 lens of the number required, in which case its counter- part only need be inserted in the other disc. By combining a positive with a negative glass of different power, there results-a lens Avhose refractive poAver is equal to the difference between the powers of the lenses used. It is obvious that the resulting lens Avill be positive if the positive glass is stronger, and negative if the negative glass is stronger. With these glasses a large number of combinations can be made. In Fig. 14, there is shown Kuapp's single-disc Oph- thalmoscope. In a letter received from the inventor, it is described as "a single disc of 5cm. in diameter, with thirty lenses, centered and covered, the hole of the mirror 3.5mm. in diameter. The series of glasses isO, plus 72, 42, 3(5, 24, is, 15, 12, 10, !», 7, (I, 5, 4, 3; and the same negative series Avith the addition of minus "The construction is like that in the Ophthalmo- scopes Avith 24 and 33 lenses. The inches are marked above, the dioptrics below." Opposite is the representation of Loring's instru- ments. The uppermost one is that of a back view of his student's Ophthalmoscope; the one on the right, the same of his single disc; on the left, the same of his dou- ble disc. The lower central cut represents the " tilt- ing mirror," the peculiarity of his later instruments. 34 1HE OPHTHALMOSCOPE; A description of his double-disc instrument, mainly abridged from the Transactions of the American Oph- thalmological Society, ] from 0.5 to 8 plus, and from 0.5 to 9 minus, or sixty-five glasses in all. The value of the glasses and the combinations is read off on the disc by a method peculiar to the instrument. This consists in having two concentric rows of figures, the outer of which shoAvs the real value of the glass, and the inner the result of the combination when the supplementary glass is over the hole of the mirror. As the plus glasses are in white ard the minus in red, ITS THEORY AND PRACTICAL USES. and as the outer i-oav is shut off when the inner is opened, no possible confusion can occur. Should the combination not be wanted, a trifling displacement of the quadrant to either side of the mirror hole at once dissolves it, and the instrument becomes a single disc Ophthalmoscope. The mirror of the instrument is Lorinjr's « tiltino-" mirrcr, which is a modification of the old mirror, ob- tained by cutting off the sides of the ordinary concave mirror, producing thereby a parallelogram 18mm. in diameter, and 34mm. in length. " The idea Avas sug- gested by Wadsworth's small circular mirror. Unlike this, hoAvever, it is designed for both the upright and inverted image, thus obviating a change of mirrors, it being found that abundant light is obtained for both methods. The mirror is SAvung on pivots which allows a tilting to either side of about 25 degrees. By this means the inclination of the correcting lenses is avoided, by which a large quantity of light is saved, and the image rendered free from distortion." The inventor lays great stress on this peculiar tilting as a very necessary adjunct for all who Avish to make au easy and accurate examination by the direct method. A brief comparison of the excellencies and aefects of these, and other instriunens, wil be found in the next chapter. CHAPTER V. DESCRIPTION OF DIFFERENT INSTRUMENTS (CONCLUDED)► It being an almost hopeless task to enumerate the names even of those who haveinvented Ophthalmoscopes,. those to be first recommended have been designated in the preceding chapter. As in other inventions the inventor has been greatly aided if not surpassed by contemporaries in the execution of mechanical details,. so Avith the Ophthalmoscope. Much may therefore be gained by a glance at a few of the best known manu- factures. * Of the instruments commonly selected by a novice, that of Liehreich, represented in Fig. 16, is undoubted- ly oftenest chosen. Probably this is largely the case because it is the cheapest. It is, however, nearly al- Avays too cheaply made for accuracy, and too limited in its range for the highest classes of ophthalmic Avork.. The auxiliary lenses, feAv in number, are packed! in the box Avith it, as illustrated in the cut. *Carter in his work on Diseases of the Eye (American Edition, Green, p,. 147,) writes that Charriere, of Paris, has foru.ed a museum of forgotten eye- instruments. I called to see it, liop.ngto find among the other instruments a collection of Ophthalmoscopes, but was informed that no such collection. had ever been made. US THEORY AND PRACTICAL USES. D< Jaeger's, Fig, 17, as modified by b'chnabel, Hirsch- benr, and others, mainlv holds the field abroad, and very justly; it is being somewhat superseded in consequence Fig. 16. of the at least superior workmanship of the American inventions. Its great advantage is that it allows the mirror to be inclined independently of the correcting passes, (as does Wadsworth's, Loring's, etc.,) so that the observer always looks through the lenses in the direc- tion of their axes, thus avoiding the apparent astigmat- 58 TnE ophthalmoscope; ism which results from their inclination, and permits of the light being placed over the head of the patient. In this latter peculiarity, it has few competitors. Nachet's Fig. 18, is a handy little affair to catch Fig. 17. Fig. 18. rglimpses; its main claim to use rests on the fact that it can be putiin the vest pocket. Landolt, who has given us much advice on this and kindred subjects, has given us an Ophthalmoscope of his invention. The claims for it rest on a smaller disc :and larger lenses than most other instruments, combined with a peculiar method of reading the combinations ITS THEORY AND PRACTICAL USES. 59 without difficulty. The lenses are piano-spherical, their plane surfaces being applied to each other. Wadsworth, Couper, Noyes, Badal, Baumeister, Wecker, Galezowski, and many others have added to and taken aAvay from existing Ophthalmoscopes, as well as invented more or less new portions, but all have used the concave mirror. Zehender's Ophthalmoscope may be taken as a sample of those with a convex mirror. This instrument con- sists of a convex mirror with a radius of curvature of 16 centimetres. The mirror has a funnel-shaped per- foration at the centre; "at the sides of the mirror are two flexible arms, one of which holds the correcting glass while the other carries a convex lens of 13 diop- tries having about the same diameter as the mirror. The observer gives to this lens such an inclination that it concentrates the light from the lamp at the side of the patient on the mirror. The arm holding the lens is adjusted to the side of the mirror next to the light, to the right or left, as the case may be." Ophthalmoscopes have also been devised with plane mirrors, prismatic mirrors, and silvered lenses or men- isci. From the array of distinguished names, the owners of which have lent their talents to the perfection of this instrument, it would seem that the subject Avould fJO THE OPHTHALMOSCOPE; be thoroughly exhausted, and as near perfection as is possible attained. But it must be remembered that "strict philosophical precision and practical utility are two different things." The demonstrating Ophthalmoscope deserves mention as an instrument devised for the purpose of aiding the learner of ophthalmoscopy early in his study of the subject. It can hardly be called useful, after a person has become skilled, except it be for the purposes of teaching. The form of the instrument devised by Mr. Carter is one of the best, and I cannot do better than to describe it substantially in the author's own Avords. Mr. Carter says: "A variety of demonstrating Ophthalmoscopes have been devised, each intended to be so adjusted by a skilled person, that one Avho is un- skilled may be able to look into the instrument as he Avould into a microscope, and to see the optic nerve and retina. These demonstrating Ophthalmoscopes are all designed to show the inverted image, and they all labor under the same serious disadvantage, namely, that al- though, in studying the inverted image, it is constantly necessary to move the mirror and lens independently, yet these parts are so connected, by some kind of tube or bar that the readjustment of one implies the de- rangement of the other. In some even the lamp itself is attached to the instrument; and, in others, rods or ITS THEORY AND PRACTICAL USES. 61 stems project from the tube, and rest on the forehead of the patient, Avhose slightest move will put everything out of gear. To obviate these inconveniences, I devised my oavii demonstrating Ophthalmoscope, starting Avith the principle that every part of it should be absolutely independent of every other part, and capable by itself of quick and easy adjustment. For this purpose the mirror and lens are placed upon separate pedestals; a similar pedestal supports the chin of the patient, and they all stand upon a table Avhich also carries a lamp, and on which they may be moved freely. My first trials with this arrangement satisfied me that it would work better than any other; and also shoAved that it could be made to afford an image of greater enlargement than any other, as well as a brighter illumination. It has already been pointed out that the greater the focal length of the object lens the greater Avill be the size of the image; but the limits of enlargement thus attain- able by hand instruments are soon reached, and an ob- ject lens of greater focal length than three inches is not available in practice. The object lens gives the best results when it is held at its own focal length from the cornea of the patient, and Avhile this is done it is very desirable that an extended finder should touch his orbit, and thus steady the hand. In this direction, therefore, the focal length of three inches cannot be exceeded: 62 THE ophthalmoscope; while on the side of the observer, there is a limit im- posed by the length of the arm. A lens cannot be held steadily and comfortably when the arm is fully extended, nor at more than twenty inches from the eye of the observer; and if the image is formed much Avithin this distance there is but little left for his visual range. But by using a table Ave are rendered independent alike of the steadying finger and of the length of the arm, and may increase the distance between the patient and observer without limit. I therefore use an object lens of eight inches focal length, which gives a very large image, sixteen inches from the eye of the patient; and I place my mirror forty inches from the eye of the patient, Avhich gives a visual distance of twenty-tour inches for the observer."* "In order to obtain sufficient illumination, the lamp is brought up from its usual position, and is placed nearly in the focus of the mirror, while the face of the patient is guarded from direct lamp-light by the inter- position of a metal screen. For use without Atropine, *"In Mr. Carter's demonstrating ophthalmoscope the place of the inver- ted image is greatly influenced by the refractive condition of the eye under examination. It is only when the examined eye is of normal refraction that the image is formed at the focus of the object lens ; in myopia exceed- ing one-eighth the image lies between the examined eye and the lens; while in hypermetropia the power of the object lens may be inadequate to the formation of an image at any useful distance. This constitutes a defect which may, however, be overcome in a great measure by having stronger object lenses for the different grades of hypermetropia."' ITS THEORY AND PRACTICAL USES. 63 and in order to avoid contraction of the pupil, a plate- of glass slightly tinted with cobalt blue, is interposed between the flame and the mirror. This filters out, so to speak, the yelloAV rays, which are the most irrita- ting, and leaves only a soft blue light, which the most sensitive eye can bear without distress. The best, because the whitest and purest light, is that furnished by the Silber Argand burner consuming either gas or oil; and it should be so arranged in any case as to be capable of adjustment to any height that may be- desired. Any good burner constructed on the Argand principle will answer." With all the instruments described, the observer can employ but one eye at a time while making observa- tions. In order that he may obtain the advantage of employing the vision of both eyes, an instrument called a binocular Ophthalmoscope has been devised. That binocular vision has advantages over monocular is well known. With both eyes, inequalities of surface, ex- cavations, tumors, etc., can be readily made out, and their extent determined. The binocular Ophthalmo- scope, although ingenious and sometimes useful, is not commonly employed owing to its being less easily- adapted to the Avork that the simple monocular instru- ment. Experience in using the latter goes far towards 64 THE OPHTHALMOSCOPE; compensating for qualities Avhich it does not possess, and renders the former Avholly unnecessary. Fixed Ophthalmoscopes, provided Avith means of sup- porting and adjusting the patient's head in desired posi- tions; aut-ophthalmoscopcs, by means of Avhich a per- son Avith ore eye may examine the fundus of his other eye; and those permitting tAvo or more observers at the same time, are forms of instruments Avhich may be mentioned as interesting but not essential, We may conclude our glance at the different Ophthal- moscopes Avith the following deductions: It is essential that in all instruments the eye-hole be not less than three millimetres in diameter, otherwise »it will act as does a stenopeic apparatus in improving the vision. An oblique mirror aids the beginner to command the >erect image much sooner than the ordinary conca\re miirror; hence, in this respect at least it must be an advantage; and the instruments Avith it (Jaeger, Lor- •ing, etc.,) have an advantage in this respect over those without it. When the correcting glasses are too small, part of the light employed goes to dazzle the patient Avithout contributing to the brightness of the retinal image under examination. This is because the brightness of an object, though not essentially interfered with when ITS THEORY AND PRACTICAL USES. 65 seen through a fair-sized glass lens, rapidly diminishes as the diameter of the lens becomes less than that of the im- age of the pupil as formed by the corneo-aqueous system. The light used for illumination ought to be behind the head of the patient, to prevent the inconvenience of the heat; for the oblique incidence of the light is lessened in proportion as the illuminating flame is placed nearer to the straight line between the centers of the observed and observer's pupils. Although experience goes far toAvard correctino- inherent defects in any instrument with which we become familiar, all instruments Avith a flat revolvino- (Eekoss) disc, and the ordinary concave mirror, (Knapp, Landolt, etc.,) having the focal distance of their lenses in such disc calculated for vertically impino-- ing light, must change and shorten the same by the necessary oblique position to sufficiently illuminate the pupil. In this respect, they are at a disadvantage as compared with those which permit of an inclination of the mirror separate from the disc (Jaeger, Loring, etc.). That such a disadvantage is not a very serious one is readily admitted. I have used one of Knapp's for years with great satisfaction. Yet, the astigmatism increases with the strength of the lenses, rendering in the case of the higher powers a careful and exact estimation impossible. Further- 5 66 THE OPHTHALMOSCOPE; more, "the astigmatic distortion of the image, which is induced by an oblique position of the stronger glasses, impedes the sharp distinction of the minuter details and interferes with the objective diagnosis of an exist- ing astigmatism." CHAPTER VI. THE PRACTICAL APPLICATION OF THE OPHTHALMOSCOPE. A skillful operator can obtain in most eyes a very good idea of the condition of the fundus Avithout the nse of a mydriatic. It is usually quite unnecessary in •cases Avhere it is only desired to examine the optic disc and its immediate vicinity. In such cases, care should be taken to use a moderate degree of illumination only; a bright light causes contraction of the pupil, and daz- zles the eye of the patient to such an extent that it is almost impossible to relax the accommodation. When it is found necessary to dilate the pupil, a solution of the pure neutral atropia sulphate, of the strength of one grain or less to the ounce of pure Avater, should be used. Put one drop of this solution in the eye to be examined, and Avait until the pupil is dilated. Generally but one pupil should be dilated at a time, and the Aveaker the solution of Atropine employed, the less inconvenience the patient will suffer from its effects upon the vision. In respect to time of dilatation, homatropine may be used to advantage. A solution of one to tAvo grains to the ounce of distilled water will 68 the ophthalmoscope; dilate the pupil, and its effects be gone in about twelve- hours. In all cases the patient should be told of its effect, and even then an ignorant one may blame you for "blinding his eyes." Such interference with the vision soon passes off hoAvever. If no Atropine be used, the dilatation of the pupil of the eye to be examined can be increased somewhat by bandaging the other eye, a course not to be recommended usually, since that eye is needed for fixation. The Direct Method of Examination.—In Fig. 19 may be seen a position in Avhich, unfortunately, many use the Ophthalmoscope, and a way I have seen recom- mended in ophthalmic literature. It should be understood that this is not the best manner in which to use this instrument, and the begin- ner Avill do well to carefully observe the following directions, noting wherein they differ, both in the direct and indirect methods, from what may be seen in the figure. The room should be darkened and the patient seated erect near a table, resting his arm upon the table to steady himself, or with his back firmly supported by a chair. A light with a clear steady flame, should be stationed to one side and about a foot behind the palient's head; it is better, but not essential, to be upon the side of the head corresponding to the eye to ITS THEORY AND PRACTICAL USES. 69 be examined. Any good light Avill ansAver, and it is unnecessary to have any of the expensive or patented standards, though Avhat is known as an oculist's bracket, Fig. 19. Avith a double-armed adjustable swinging movement, is very convenient. The surgeon iioav seats himself opposite the patient, their eyes on a level, or nearlv so, and this position is best attained by having one or each seated upon a re- 70 THE OPHTHALMOSCOPE; volving adjustable chair. The surgeon may use either eye for examination of one of the patient's eyes, but it is preferable to use the one corresponding to the one to be examined, that is the right for the right, and the left for the left. Let him take the Ophthalmoscope in his right hand, if he is about to use his right eve, delicately holding it by the handle near its free end, and lightly resting the upper portion of the rim of the mirror against hisbroAV Avhile he applies his eye to the sight-hole. He should now momentarily close his companion eye to be sure he is looking through the sight-hole, and then keep both eyes open. The mirror must be so inclined to the light that the reflection will fall directly upon the patient's pupil. Having thus far followed directions, the pupil of a healthy eye will present a reddish appearance from the bright reflection of its fundus. The patient should now be directed to look slightly inward and fix his gaze upon some distant object over the surgeon's right shoulder, and about on a level Avith the tip of his ear. If his left eye in to oe examined, he should look over the surgeon's left shoulder in the same manner. The reason for the patient's looking at a distant object has already been explained. As soon as the eye is turned inward, the red appear- ance of the pupil changes to a light yellow, seemingly ITS THEORY AND PRACTICAL USES. 71 white iii persons of dark, swarthy complexions. This change is 2aused by the optic disc coming into view. The disc is usually the starting point in exploring the surrounding parts of the fundus, but before proceeding to a closer examination it is Avell to first ascertain from a distance Avith the Ophthalmoscope whether the red re- flection of the fundus is clear. Some slight opacity of the lens or vitreous may thus be detected, and explain an appearance which would perhaps othei wise be re- ferred to the fundus. Next the surgeon should ascertain if the refraction is normal by observing if the retinal vessels can be seen clearly from a distance. If the vessels are distinctly visible at a distance, the eye is either myopic or hyper- metropic; the first if the vessels move in an opposite direction from the observer's head Avhen moved side- ways, and the second if they move in the same direction. In emmetropic eyes, the details of the fundus can only be distinctly seen at a distance of two or three inches from the patient's eye, Avhile in the other conditions, myopia and hypermetropia, the mirror must be held at a distance of about fourteen to sixteen inches. Hoav- ever, if an appropriate correcting lens is held behind the mirror, the emergent rays from the fundus of the patient's eye may be rendered parallel, and a clear image obtained at a short distance, the same as in em- 72 THE OPHTHALMOSCOPE; metropia. A concave correcting lens will be needed for examination of myopic eyes, and a convex for hy- permetropic eyes. The power of this correcting lens will, of course, depend upon the degree of myopia or hypermetropia to be overcome. Furthermore, as there are usually unconscious efforts of accommodation in either the eye of the observer or of the observed, a ten or tAvelve inches concave correcting lens may be found useful in examining an emmetropic eye. These uncon- scious efforts in the eye of the examiner may also be overcome by experience, those of the patient by atro- ponization. The direct method shows only a very limited field at a time. Seemingly the more simple, it requires much careful and patient practice for its mastery. Its impor- tance will be made clearer farther on. The Indirect Method of Examination.—This method, illustrated in Figure 19, requires the use of one of the large convex lenses in conjunction Avith the mirror. The lens of two and one-half or three inches focal distance is most commonly used. Follow- ing the manner laid doAvn in the direct method as far as necessary, the surgeon then takes such a lens be- tween the thumb and forefinger of his unoccupied hand and brings it up before the patient's eye from the outer (temporal) side, resting his extended little finger ITS THEORY AND PRACTICAL USES. 73 on a spot near the temple to steady the hand. Not moving his little finger from its resting place, nor the Ophthalmoscope from his brow, he tells the patient to look slightly inward and observe some distant object, as in the indirect method, and at the same time adjusts the lens to its focal distance. The reflected rays from the mirror now pass through the interposed lens and enter the pupil. The mirror is held at some distance in all the conditions of refraction ; for by the use of this lens the distinctions of myopia and hypermetropia and in- voluntary accommodation in the observed eve may be practically disregarded so far as searching for a distinct image is concerned. This image has been shown to be actually on the observer's side of the lens, inverted and in the air: and the observer's eye need only be moved a little nearer in myopia, and a little faither aAvay in hy- permetropia, in order to see it well. If the optic disc is only partly in view, it can be brought fully under ob- servation by the surgeon moving either his head or the objective. The image moves in a direction opposite to the movement of his head, and in the same direction as1 the movement of the lens. There may of necessity be some bending movements of the surgeon's body while properly adjusting the mir- ror, the objective, and his distance from the patient; but there is no necessity to crouch down, slide over the 74 THE OPHTHALMOSCOPE; chair seat and fumble the patient's nose or face, per- haps hitting his eyeball. Not only is it unnecessary, but it often alarms a young or timid patient, or dis- gusts one older and more confident. These points are not only urged because proper, but because essential to complete success. If the surgeon's body be screwed around, he will also perhaps get an imperfect vieAV,and if he obscures the eye not under observation by bring- ing up the object lens from the nasal side, or by raising his elboAv, or by making any aAvkward motion, the eye under examination Avill wander and prevent a perfect view. An apt student will soon become able to easily move his head in various directions, all the while keeping the light accurate!}' focussed upon the pupil. Not only should he become adept in this, but also in focussing a clear and sharply defined image of each detail. The head of the observer must be at such a distance from the aerial image as is sufficient for the preception of small objects. The image may be enlarged with ad- vantage by using a convex lens of about ten inches fo- cus behind the mirror. Lateral, or Oblique Illumination.—This method of ex- amination may be employed with much benefit for parts of the eye as far back as the posterior lens capsule. ITS THEORY AND PRACTICAL USES. <0 It is much used in conjunction with the Ophthalmoscope, hence its consideration here. In Fig. 20, illustrating this method, the lam]) is placed in advance and to one side of the head of the patient and the observer sits in front or stands behind Fig. 20. the patient. Either lens may be used to concentrate the light from the lamp upon the patient's eye, and the other lens used as a magnifying' glass, if desirable, through which the observer looks at the parts under examination. Diffused daylight may also be employed. By successive movements of the patient's eye, occasion- 76 THE OPHTHALMOSCOPE ; ally varying the position of the lens, the cornea, crystal- line lens and iris may each be thoroughly examined. In the diagram the surgeon is supposed to be seated and viewing the eye through the 2 inches lens, the ilight being concentrated by the 3 inches lens. All changes of the crystalline lens and parts anterior to it may be seen in their true colors, but Avith the Ophthalmoscope all opacities appear black. Foreign bodies, nebulae, synechia?, etc., invisible to the eye alone, may be easily defined by this method. The minutest ;facet or indenture on the cornea may also be detected by placing the patient Avith his face toward a AvindoAV through which strong daylight is falling. Any such irregularity Avill at once become apparent by the seem- ing "shooting off," or dispersion of the rays from it, looking on a smaller scale not unlike a mirror indented and cracked by a sharp bloAv which causes the glass to splinter. It is best seen by looking in a direction nearly at a right angle to the course of the incident rays of light. CHAPTER VII. THE RELATIVE VALUES OF THE DIRECT AND INDIRECT METHODS, ETC. The relative value of the direct and indirect methods has been the subject of much contention, often being the guiding point in the construction of a particular Ophthalmoscope, so much so that one may judge quite- accurately which method the inventor preferred. Unquestionably he who allows his prejudices to carry him to either side to the neglect of acquiring the whole subject, fails to excel in the use of the instrument. Both are so valuable that they should be thoroughly comprehended. In support of the advantages of the direct method, I, could do no better than to cite the argument of Prof. Hirschberg, of Berlin. Whoever wishes to have a clear insight into the diop- tric condition of an eye ought to view the retinal image Avhich is formed by that eye as directly as possible, and that in most cases is the erect image, or in cases of ex- treme myopia the inverted, as seen without correcting glasses. For whenever a strong convex lens (of from. 78 THE OPHTHALMOSCOPE; 2 to 4 inches focus) is superadded to the dioptric system of the eye under examination, unless care is taken by means of fixed apparatus to minimise spherical aberra- tion and oblique incidence of the light, that lens has a predominating influence upon the character of the image, and the estimation of the independent condition of the eye is rendered difficult. In the old treatises on optics Ave meet Avith the statement, important in practice, that with a convex lens of short focal distance, the inverted images of all objects farther removed from the lens than ten times its principal focal distance lie nearly in one and the same, that is, the posterior principal focal plane. Hence in the method of the inverted image the ^unavoidable error would at the least amount to from l-20th to l-40th of an inch. In reality, it is even greater, owing first, to the impossibility of securing and main- taining the best position of the object lens ; and second, to the optic imperfection of the lenses commonly em- ployed, Avhich are mostly left too thick, so that spheri- cal aberration is not sufficiently guarded against. Professor Schmidt-Rimpler uses for the inverted image the shadoAV from a crossed grate of metal in front of the flame, as Coccius (Stimmel) does for the erect image. Whilst the flame placed laterally with the grate before it, as well as the eye under examination with a four inches convex lens, held about four inches in ITS THEORY AND PRACTICAL USES. 79 front of it, remain fixed, the head of the observer, with the concave mirror before it, moves gradually back- Avards. A conveniently attached tape-measure Avith a ratch serves to measure the greatest distance (a) be- tween the mirror and convex glass, at which the grate's shadow appears distinct upon the retina's image between the papilla and fovea. While the flame and the grate continue unmoved, the distance (b) is meas- ured from the mirror to the place of the grate's image formed by the concave mirror alone. The distance d= a—b denotes the refraction of the examined eye, since d in emmetropia is equal to/(that is, the focal distance of the convex glass); and it is less than/in myopia and greater than /in hypermetropia. Having first worked Avith the original apparatus as described, Hirschberg then employed a narrower grate, and simplified the method by omitting the second meas- urement. "Being myopic, I have my far point at a fixed distance; anyone not myopic may render him- self so by means of a proper convex glass placed behind the sight-hole of his mirror. Henceforth a only need be measured and the fixed distance deducted from it, in order to determine d. Upwards of a hundred careful observations, with a comparative trial in each case of the erect image, have proved that Avhilst Schmidt's plan can ahvays be easily and expeditiously accom- 80 THE OPHTHALMOSCOPE; plished, the latter is yet the more accurate of the two, and affords the additional advantage of a considerably magnified im 'ge of the most important region of the fundus. And again, the grate's image formed by the concave mirror held obliquely is astigmatic, i. e., the horizontal and verti3al shadow lines are not at the same time and distance seen with equal distinctness; so that really in every case a mean ought to be struck be- tween two observations. It is self evident that, under such circumstances, the determination of an existing astigmatism cannot be an easy matter. The less ob- lique the incidence of the light upon the mirror, the better are the results, as we have seen before. Finally we must remember that on account of the strono- h>ht of the reflector, it becomes rather difficult for the pa- tient to relax his accommodation." To such a degree, in the comparison of the direct with the indirect method of examination, the former can certainly hold its own. Arid now it remains in conclusion, to consider the direct method in regard to its absolute value. Mathematically, the method of the erect image is not exact itself, since a loupe, whether a compound convex lens or having, like that of Brucke, a concave ocular, is not, in reality, an adequate means for meas- ITS THEORY AND PRACTICAL USES. 81 uring distance* If Avith a loupe Ave obtain a distinct image of an object A, Ave are not able from the known focal distance/of the loupe to calculate the unknown distance a of the object from the loupe, because we do not Iuioav to Avhat degree the accommodation of our eye had been relaxed. Hence, neither the older nor the more recent attempts, particularly by military sur- geons, to utilize the loupe (after the example of Bu- row), for the subjective estimation of the refraction have been able to secure the approval of ophthalmolo- gists. Yet it certainly makes a great difference whether the eye, looking through the loupe, is that of a recruit or a random patient, or whether it is that of a medical observer; for the latter is certainly able, in a short time (say Avithin a few hours, or days, or weeks), to learn Iioav to see through a loupe; in other Avords, to use the Ophthalmoscope Avithout any appreciable ex- ertion of the accommodation. AYhile this latter statement has by some observers been doubted, their isolated experience should not be allowed to Aveigh against the testimony of others avIio find that in the repeated examination of the same eye they have invariably to resort to the same glass for cor- rection of the ametropia. A good revolving Ophthal- moscope facilitates the examination materially. While •It is different with an astronomical telescope. 82 THE ophthalmoscope; doubtless this poAver of relaxation of the accommoda- tion so essential varies in different individuals, I be- lieve a great cause of dissent to be the imperfect state of most of the instruments still in use at the present time, combined Avith the lack of application and thorough working out of details so essential to the mastery of all nice points. There is further ahvays this little draAvback attach- ing to the direct method, that Ave do not adjust for the fovea centralis of the patient's eye, because it is optically too little marked, and also because its being made the point of fixation involves an undue contraction of the pupil. In the method of Coccius (Stimmel) this fault is pretty Avell guarded against. A convex lens covered with a metal grate is in front of the flame; the incident pencils of luminous rays are rendered parallel, and are by a small plane mirror reflected into the eye to be ex- amined, which, in its turn, is corrected for parallel rays by a glass held as straight as possible in front of it. The general practice hoAvever, is to put up Avith the flame of an ordinary lamp, and to accomodate for the lateral edge of the papilla, or for one of the fine blood- vessels coursing from the optic disc towards the macula lutea, the bright central lines of Avhich are very readily perceived, or for the ring of connective tissue at the lat- eral edge of the papilla, or the granular aspect of the ITS THEORY AND PRACTICAL USES. 83 fundus (the retinal epithelium,) thereabouts. Now the lateral edge of the papilla is about 3mm., or 12 angular degrees distant from the fovea centralis, and still it is the refraction of the latter (i. e., its relative position to the principal focal point of the quiescent dioptric system of the eye) which Ave are seeking to determine. Experience shows that in cases of emmetropia and hy- permetropia the error is but very slight, as is confirmed by the controlling trial of glasses for the correction of the atropinized eye (Mauthner, Schnabel, etc.,) where as in myopia, even of moderate degree, the difference is sometimes found to amount to l-36th of an inch. In cases of ametropia, however, Avhich call for 10 D or 12 D or upwards, as e. g.. in aphakia, the error (0.5 D to 1 D) is utterly insignificant. It is not the absolute, but the relative amount of the latter which requires to be Aveighed; nor must Ave lose sight of the fact that, in many disquisitions on physiological optics, the best authors, physicists as Avell as physiologists, look upon errors, amounting to from 5 to 10 per cent, of the quantity sought, as matters of course. It has no sense, at the present time in our examination of patients, to aim at any greater accuracy. If approximately correct- ing glasses are supplied in a case of hypermetropia of 12 D, a slight forward or backward movement imparted to the spectacle-frame suffices to alter the strength of 84 THE OPHTHALMOSCOPE ; the glass by more than 1 D. It is, therefore, quite un- necessary, so far as the stronger glasses of the refraction Ophthalmoscope are concerned, to retain the interval of 0.5 D. Beyond 10 D or 12 D, it is better for the rapid and sure determination of the proper glass to have the interval equal to 2 D. In the method here advocated Ave estimate, it is true, the refraction of the eye for red light, and not for that of the greatest brightness, with which, hoAvever, ordi- nary vision is concerned. Badal makes the difference to be equal to 0.75 D, but a simple calculation sIioavs it t o be no more than 0.25 D, and hence entirely insignifi- cant. In adjusting for the fine median blood-vessels, we de- termine in reality the refraction of the vascular instead of that of the sentient layer of the retina, the distance betAveen the tAvo being a small fraction of 1 m. The thickness of the retina between the papilla and fovea is about 0.3 mm. Hence the possible error is certainly less than 0.15 mm., that is under plus 0.5 D,seeing that in the schematic emmetropic eye a distance in depth 0.3 mm., corresponds to a difference of refraction equal tol D. All these trifling errors interest us only in connection with the question whether such slight deviations from the emmetropic condition are capable of being diagnosed. ITS THEORY AND PRACTICAL USES. 85 In cases of pronounced ametropia, they may be left out of account entirely. The conclusion is, then, that in the direct method, pure and simple, Ave have a secure means of establishing the presence even of an ametropia of 1-lxth of an inch, that is one corresponding to one of the weak glasses of the ordinary trial cases, (the weakest in some foreign ones.) This quite accords Avith the experience of many that the objective method of determining the refraction for the most part yields more exact results than the sub- jectiA^e, in Avhich Ave depend solely on the statement of the patient.* The former frequently discloses small dif- ferences between the Iavo eyes, of which the patient had not become aAvare in the selection of glasses. Among other advantages of the objective method, it is far more expeditious than the subjective method. It is also of much more extended scope, being equally ap- plicable in the cases of children and illiterate persons, of simulation and amblyopia; and, finally it enables the analysis of astigmatism, qualitative as well as quantita- tive, to be made in the most reliable manner. Yet, for all that, Ave cannot dispense Avith the trial-case. It is always advisable, Avherever it can be done, to confirm by the subjective method. *Sue note at the foot of page 50. CHAPTER VIII.] EXAMINATION OF THE HEALTHY EYE. It is assumed that the reader, who undertakes to employ the aid of the Ophthalmoscope, has first from books at least, gained a fair knowledge of the anatom- ical structures of the eye, together with their names and relations. It Avill therefore not be deemed neces- sary in the succeding pages to explain the terms em- ployed. As in every other branch of physical diagnosis, a familiarity with the appearances in health is necessary to the detection of disease, so it is with the eye; the condition of the parts in health must be the standard by which to estimate the nature and extent of disease. Let the student first apply himself to the study of the normal structures, and learn to recognize them in all their variations, and he may then, and not until then, proceed intelligently to the complete mastery of the subject. Color of the Eundus.—As already mentioned, the reflection from the fundus is reddish, but its tint varies greatly in different individuals. "Among dark races the fundus of the eye is of a brownish gray color, while ITS THEORY AND PRACTICAL USES. 87 among the European races it is more of a crimson orange." The variations of color and tint depend upon the amount and color of the pigment filling the cells of the choroid and obscuring to a greater or lesser degree the choroidal vessels. In people of very light complexion, the fundus is often found to be of a bright scarlet color. Such is the case in the SAvede, while in the Italian or the Spaniard, the color is proportionately darker. Examination of the fundus can hardly be regarded as complete Avithout the employment of both the direct and the indirect methods of exploration. The first shows only a very limited portion at a time, but this portion is highly magnified and in its true color. The second shows a large field at a time, and enables the observer to note the relation of the parts more accur- ately ; but the color of the image is not a true repre- sentation of the color of the object, nor is the image so highly magnified as by the direct method. The Optic Disc.—The disc or papilla, is the point where the optic nerve terminates or expands into the retina. It is usually round, or slightly oval Avith its long diameter vertical. Its color varies, and the darker the eye, the Avhiter the disc appears by contrast Avith the surrounding choroid. The color is generally pink 88 THE OPHTHALMOSCOPE; or rosy, and varies from this to a steel gray. In very dark eyes the disc appears white. The color is derived from three sources,—the Avhite of the connective tissue, the red of the capillaries and the bluish-gray of the nerve tubules. The circumfer- ence of the disc is well defined; it is enclosed first, by the Avhite ring of the sclerotic, and second, by the darker choroidal border. The sclerotic ring Avhich encloses the nerve appears as a slender zone of Avhite, usually most marked at the outer side of the disc. Sometimes only a portion of this ring can be seen, or it may even be entirely ob- scured. Outside of the sclerotic ring, the border of* the choroid is plainly seen. Its general color is brownish- gray, but the outer border is often of a darker hue, owing to a crescentic shaped deposit of pigment in this situation. The central surface of the disc is depressed below the general level, and of a Avhitish appearance. It fre- quently has a stippled look caused by the holes through Avhich the bundles of nerve fibers pass. It is at this point that the arteria centralis retince and the accompanying vein pierce the optic nerve. This de- pression is called the porus opticus, and its Avhite appearance is due to the connective tissue enclosing the vessels. ITS THEORY AND PRACTICAL USES. 89 Although the central artery of the retina usually pierces the disc at its center and bifurcates as soon as it emerges, one branch passing upwards and the other downwards, such is not always the case. The artery may appear at other points of the disc, and has been observed to emerge as several branches. After bifurcating, the branches continue to divide dichoto- mously, continuing in all directions towards the spontaneous pulsation may be noticed in the central veins, and this may be aug- mented by gentle pressure upon the eyeball. The veins are of a darker and of a more uniform color than the arteries, and they usually pass under the latter. The apparent calibre of the vessels Avill be found to differ Avith the magnifying poAver used. The arteries, in contrast with the veins, are straighter, of a brighter red, smaller, and the pulsation cannot be seen. They usually cross over the veins, and along the center of 90 THE ophthalmoscope; each may be noticed a bright whitish line. This whit- ish line is scarcely observable on the veins. Figure 21 is copied from a drawing by Jaeger, and represents the healthy appearance of the disc as seen in the erect image. The dark vessels are the veins, the light ones, the arteries. The Avhole is much enlarged. Color of the Disc.—This is not uniform, the inner half being of a pinkish tint, and the outer half present- ing more of a gray or mottled appearance. The inner portion is more of a pink than the outer, oAving to its being more thickly covered with nerve fibers and ves- sels. The central depression, its whitish appearance, the outer grayish mottled hue, and the more decided pink of the inner half, are all subject to considerable variation, but are characteristic marks in most healthy eyes. The lletina.—The retina is so nearly a transparent structure that it reflects very little light and is there- fore generally invisible. In very dark persons it may sometimes be seen lying over the choroid as a grayish layer. Its appearance may Avell be likened to the bloom on a peach. The macula lutea, or yellow spot, is not easily recog- nized, but it is situated on the axis of vision about one or tAvo lines outward from the disc. No retinal ves- ITS THEORY AND PRACTICAL USES. 91 sels cross this spot; they pass either above or below. This fact helps to determine its position more readily. The color generally seems to be a bright red, and in the center is a bright spot known as the fovea centralis, or central pit. The Choroid.—The anatomy of the choroid shows it to be a vascular and pigmentary structure. An elastic lamina lies innermost, and close behind this, separated from it only by the hexagonal cells, lies a dense capil- lary network. The larger choroidal vessels lie next to the sclerotic, and among them are distributed the most of the pigment cells. In persons of dark complexion, the hexagonal cells conceal the choroid from vieAv; but in persons of a lighter hue, these, cells contain no pig- ment and allow light to pass to the vascular structures. This explains the scarlet appearance of the fundus in the latter, and the brownish-gray appearance in the former. As a method of acquiring dexterity in using the Ophthalmoscope, it has been recommended that begin- ners undertake to make sketches of the disc, and a portion of the surrounding fundus in some person's eye. The frequent repetition of hudng clown and re-adjust- ing the instrument, soon gives that ease and celerity to ft ' ft ^ the operation Avhich is so desirable. CHAPTER IN. OPHTHALMOSCOPIC APPEARANCES IN DISEASE AND MAL- FORMATIONS. Opacities.—These occur in the cornea, lens and vit- reous, and are therefore situated at different depths. As far back as the posterior lens capsule, as has already been noted, opacities may be seen in their true colors by lateral illumination, and even very minute ones may be detected; butAvith the mirror alone it should first be as- certained Avhether the media are clear. Once assured that an opacity exists, its depth should be determined, and then, if it is Avithin range, the lateral illumination may be used. With the Ophthalmoscope, opacities appear as dark spots of irregular size and shape on a red back- ground. With the lateral illumination, they generally appear as gray or light spots upon a dark background. With a very brilliant illumination, very small opacities may be invisible; it is therefore best to employ a very weak light at first. In examining for opacities with the mirror, in order to prevent the image of the fundus from obscuring or confusing them, the mirror should be held at such a ITS THEORY AND PRACTICAL USES. 93 distance as Avill prevent the observer from getting any image of the fundus. In order to do this, a lens of about eight inches focal length may be used behind the mirror and the latter be held at a distance of seven or eight inches from the eye under observation. To determine the depth of an opacity, it may be re- membered that all opacities in front of the posterior lens capsule are readily located by means of the oblique illumination. The turning point of the eye, or the point Avhich remains stationary Avhile the eye is in motion, is situated either at, or a little behind, the pos- terior pole of the lens. Now, if the eye is moved in various directions, opacities' in front of this turnino- point, or pivot, Avill move in the same direction as the cornea; and it is likewise obvious that opacities behind this point will move in the opposite direction. An opacity situated at the turning point Avould scarcely move at all. The reflection of the mirror upon the cornea does not move Avith the movements of the eye. This corneal reflection should therefore be taken as the fixed point by Avhich to measure the extent of move- ment of an opacity; and the extent and relative direc- tion Avill show the approximate depth. Opacities of the Cornea.—These are best seen by the oblique method. The unaided eye will detect those of appreciable size. With the former method, the loca- 94 THE OPHTHALMOSCOPE; tion, size and color can be easily and fully determined. Opacities of the Lens.— Sometimes spots are seen upon the anterior capsule, the posterior capsule and the lens being unaffected. Usually these are deposits of lymph or pigment resulting from iritic or corneal inflammation. Strictly speaking, the term cataract should be limited to an opacity of the lens, though the term is applied to opacities of the lens capsule as well. There are there- fore two general classes of cataract, the capsular and the lenticular. It is not my purpose to speak of cataract farther than pertains to the Ophthalmoscopic appearances of the different varieties. These will be better understood if a few leading characteristics are added. Capsular cataract is an opacity of the lens capsule, which generally encroaches on the area of the pupil. It has a whitish appearance and seldom occurs Avithout the lens itself having been previously involved. The anterior capsule is more frequently affected than the posterior. The trouble is not so much in the cap- sule itself as on its inner surface, Avhere, with the ob- lique illumination, crystals of cholesterine or chalky concretions may be seen. Lenticular cataract may be divided into four varie- ties: the soft, the cortical, the hard and the zonular. ITS THEORY AND PRACTICAL USES. 95 Soft Cataract.—This occurs among infants and young children and is often congenital. Dilate the pupil with Atropine; the lens shows a bluish-white opacity Avhich is usually uniform and free from striae. With the Oph- thalmoscope the opacity Avill be found to reach from the center of the lens to its circumference and no por- tion of the fundus will be visible. Occasionally, opaque whitish spots are noticed beneath the capsule. Under the head of soft cataract, traumatic cataract may be mentioned as sometimes analogous in appear- ance. If an injury to the lens is extensive the aqueous humor pervades its Avhole substance and renders it opaque. In slight injuries only a small and irregular portion of the cortical substance is involved. The his- tory of the case almost precludes the possibility of a mistake in diagnosis. Cortical Cataract.—Before fully formed, the cortical cataract appears as a series of striae running from the circumference of the lens towards its centre. These striae are often situated in the posterior substance of the lens, but as the cataract advances, they become Avhite, increase in breadth and finally occupy the whole lens. Dilate the pupil Avith Atropine, and the opacity "will appear quite uniform but marked with pearl-like bands, and perhaps of a yellowish tint at the centre. But with the Ophthalmoscope, it will be 96 THE OPHTHALMOSCOPE ; noticed that the margin of the lens alloAVS a few rays of light to pass from the fundus, the red reflection being seen. The central portion of the lens appears opaque and dense, surrounded by a dim reflection from the fundus. In the soft cataract, no striae or colored reflection are seen.* Hard Cataract.—Senile or hard cataract seldom af- fects a person under forty years of age. It first ap- pears as an amber-colored opacity, most marked at the nucleus, the cortic.il substance remaining comparatively unaffected. The amber-colored center is the character- istic feature throughout the course of its formation. In the earlier stages, if the pupil is dilated with Atropine, small opalescent striae may be seen extending inwards from the circumference, and as the cataract advances, these become more apparent. The Ophthalmoscope sIioavs the circumference more transparent than the center even in the latter stages. Spots of fatty epi- thelium are often observed beneath the inner surface of the capsule.t *'Tn some cortical cataracts we find only an immense number of very small dots or short streaks (dotted cortical cataract). Occasionally a single, large, wedged shaped opacity will form at some part of the cortex and rejnain stationary and solitary for many years. Sometimes, though no opaque striae are visible by focal illumination, one or more dark streaks are seen with the mirror, which alter as it is differently inclined. These "flaws" in the lens are comparable in their optical effects to cracks in glass, and must always be looked on as the beginning of cataract." (Nettleship.) t"A few cataracts beginning at the nucleus, and many beginning at the cortex, are not senile in the SL-ns? of accompanying old age, and are, there- ITS THEORY AND PRACTICAL USES. 97 Zonular Cataract.—This opacity is usually congenital, and most often occupies layers of the posterior cortical substance of the lens, and is most dense at the axis. Dilate the pupil with Atropine, and unless the case is far advanced, the Ophthalmoscope clearly reveals a portion of the fundus through the circumference of the lens. Even a dim reflection of the fundus may be seen through the denser portions. The opacity appears, by oblique illumination, as a whitish-gray film apparently upon the posterior lens capsule. Sometimes striae radiate from the central portion, but the circumference of the lens is often completely transparent. This form of cataract may be progressive or may remain stationary for many years. Dislocation of the Lens.—The lens may be either partially or completely displaced, and in almost any direction. In partial dislocation, if the pupil is well dilated with Atropine, the change in the position of the lens may be noted either by oblique illumination or by the Ophthalmoscope. Using the Ophthalmoscope by the direct method, the edge of the lens may be seen fore, not hard. Seme such are caused by dia'ietes, but in many t is imp >s- sible to say, excepting by a general reference to bad h 'alth or premature senility, why th; lens snotil 1 have beeorn: dise ised. \1 vny s icli arj known as "soft" cataracts when complete. They generally form q tiijkly in a few months. A few are congenital. Whether nuclear or cortical, tiny are whiter and more uniform looking than the slower cataracts of old age, and the cortex often shows a linear glisten like satin, or tlak3r appearance like crystalized spermaceti." (Nettleship.) 98 the ophthalmoscope; as a distinct, dark, curved line lying over the back- ground of the fundus. Not only this, but if the lens is so far dislocated laterally, as to leave a portion of the pupil unoccupied, a distinct erect image of the fundus can be seen through that portion of the pupil, and the part of the fundus thus seen will be very hypermetropic Complete dislocation of the lens into the anterior chamber can scarely be mistaken even when the lens is quite transparent. If the dislocation is backwards in- to the vitreous, with the Ophthalmoscope its location can be readily ascertained. It will appear nearly natural in outline, darker in color, occupying the lower portion of the vitreous while the head is erect. Using the oblique illumination, no reflection from the anter- ior capsule is apparent. When the lens lies partially across the pupil, it acts as a prism and a double image of the fundus may appear, but Avhen it is entirely Avith- out the axis of vision, the eye becomes intensely hyper- metropic and the details of the fundus appear very small. Changes in the Vitreous Humor. Opacities.—In in- flammation of the vitreous humor it is diffusely clouded with a grayish mist, which partially or completely obscures the fundus. Beeides diffuse opacity, there often exist opaque bodies varying much in shape and size. If the vitreous ITS THEORY AND PRACTICAL USES. 99 is in a fluid condition, these move about Avith the motions of the eye, and can readily be detected Avith the Ophthalmoscope. Opacities from haemorrhage appear bright red, unless very extensive, Avhen they may cause the whole fundus to appear dark. The loca- tion and amount of hemorrhage is subject to no rule. After absorption has begun, the color and form of the blood spots change to various irregular, fibrinous or filamentous shreds, either fixed or floating. Sy/ic/u'sis, or Softening of the Vitreous.— In a soft- ened, fluid condition of the vitreous, a large number of small bodies are to be seen suspended in its substance; in fact, unless these bodies are present it cannot be said positively that a fluid condition of the humor exists. They are often in the form of fibrinous threads, inter- spersed with crystals of cholesterine. An abundance of cholesterine crystals generally is present when the vitreous is in a fluid state, presenting a beautiful appearance. While the eye is at rest these crystals subside more or less completely toward the bottom of the chamber, but Avith every movement of the eye they become diffused through the fluid, and appear like particles of sparkling gold-dust. The term sparkling syuchisis is applied to such a condition. Foreign Bodies.—When a foreign body has entered the vitreous, if the media remain clear, the use of the 100 THE OPHTHALMOSCOPE; Ophthalmoscope will reveal its character and position. After some days have elapsed, the body is likely to be- come gradually covered with the products of inflamma- tory exudation, concealing it from view. CHAPTER X. REFRACTIVE DISORDERS. There are several ways of determining the refraction of an eye. It may be found by means of the incident light; by means of the lens necessary to use in order to see the upright image; by means of the enlargement of this image; by the distance at which the inverted image is formed; and by the enlargement of this image. The Avay most used, however, because the simplest and easiest, is that of finding the lens required by the examiner, (any ametropia of his being first corrected, and the accommodation of both examiner and patient being fully relaxed,) to clearly and distinctly see the fundus of the eye under examination. Myopia.—-It will be remembered that in myopia, the rays converge to a focus before reaching the retina. In other Avords the principal focus of the dioptric media lies in front of the retina. Hence rays issuing from the retina of a myopic eye do not emerge from the cornea parallel, as is the case in emmetropia; but coming from a point beyond the principal focus, they emerge as convergent rays. They cannot as convergent rays be brought to a focus upon 102 THE OPHTHALMOSCOPE; the observer's retina, but after they cross each other and become divergent, the observer can obtain a dis- tinct image. The image is an inverted one, as is proven by the fact that it moves in the opposite direc- tion from the observer's head. The head of the observer must be from tAvelve to sixteen inches from the eye under examination. An erect image may be seen at a short distance by interposing a concave lens behind the mirror; but the lens should be of sufficient power to render the conver- gent rays parallel. The focal length of this lens Avill approximately represent the degree of the myopia exist- ing in the eye under observation, and therefore the number of the lens necessary to correct it. Hypermetropia.—Parallel or divergent rays of light entering the hypermetropic eye converge to a focus situated behind the retina. The principal focus of the dioptric media is therefore behind the retina. Bays from the retina are therefore from points Avithin the principal focus, and in consequence emerge divergent. At a distance (sixteen to twenty inches) these rays can be brought to a focus upon the observer's retina, and form a distinct erect image. That the image is erect is proven by its moving in the same direction as the observer's head. Rays issuing from a hypermetropic eye may be ren- ITS THEORY AND PRACTICAL USES. 103 dered parallel by a suitable convex lens. The focal length of the lens Avhich will render the divergent rays parallel, enabling the observer to see a clear erect image of the eye at a short distance, (two or three inches), will give approximately the degree of existing hypermetropia. The size of the inverted image is directly proportion- ate to the focal distance of the convex lens used; and other things being equal, that of the myopic eye is smaller, and that of the hypermetropic eye larger, than that of the emmetropic eye. "The inverted image produced by a convex lens of plus J an inch, (2D [)) placed at a little less than two inches in front of the cornea is, for the emmetrope, 3.6 times greater than the object; smaller for the myope, and larger for the hypermetrope, the difference increas- ing Avith the increase of the ametropia. "The relation of the size of the inverted image of an ametrope to that of the upright image under the con- ditions mentioned, is as follows: for emmetropia, 1:5.5; for hypermetropia of 7.9 D, 1:4.7; for myopia of the same degree, 1:7.1." But in estimating the degree of either hypermetropia or myopia by these methods, one source of error must be carefully guarded. It arises from the fact that comparatively few ob ervers can, in looking at near THE OPHTHALMOSCOPE; objects, prevent the involuntary action of the ciliary muscle. To make the results of value, both the observer's and the patient's accommodation must be relaxed during the examination. Repeated practice must be had until the examiner can accomplish this relaxation, or an alloAvance must be made for that which cannot be OArercome. To practice for this relaxation of the accommodation, emmetropes and hypermetropes may look through a convex lens at objects situated ;vt the focus of the lens; and practice bringing their eyes to a parallel condition by placing before one eye a prism Avith its base imvard. It may also be found advantageous to examine the in- verted image through a moderately strong convex lens, (plus 3D.) Astigmatism, and Conical Cornea.—In most eyes the refraction Araries slightly in the different meridians of the cornea. Usually rays entering the eye in the vertical meridian are focussed somewhat nearer the cornea than the rays in the horizontal meridian. The variation is usually so slight-as to be unnoticed; but where the want of symmetry in the corneal curvature is great, confused and indistinct images are formed upon the retina and the condition is called astigmatism. Sometimes the crystalline lens presents irregular cur- vature also. ITS THEORY AND PRACTICAL USES. 105 Astigmatism is either regular or irregular; and of regular astigmatism there are three varieties, the sim- ple, the compound, and the mixed. When one principal meridian of the cornea is emme- tropic and the other myopic or hypermetropic, astigma- tism is said to be simple. If the meridian of abnormal curvature is myopic the astigmatism is simple myopic; but if this meridian is hypermetropic, the astigmatism is simple hypermetropic. When different degrees of either myopia or hyperme- tropia exist in both principal meridians, the astigma- tism is called compound. If both principal meridians are myopic, it is compound myopic. If both principal meridians are hypermetropic, it is compound hyperme- tropic. When one principal meridian is myopic and the other hypermetropic, the astigmatism is said to be mixed. Irregular astigmatism is caused by differences of re- fraction in one and the same meridian. The Ophthalmoscope is a most useful means of diag- nosis in these disorders of refraction. By the direct method, in regular astigmatism, the optic disc appears oval, and the elongation is in the direction of greatest curvature. By the indirect method the reverse is true. Sometimes in normal eyes the disc is oval; hence it will never be safe to make a diagnosis from the apparent 106 '1HE OPHTHALMOSCOPE; form of the disc by only this method of examination. If the disc; appears oval in one direction while viewing the upright image, if astigmatism is present, it should appear oval in a direction at right angles to the first Avhen viewing the inverted image1. The presence of astigmatism may also be determined by observing the relative distinctness with Avhich vessels running in different directions are seen. For example, vessels running vertically may appear clearly focussed, while those running horizontally are indistinct and con- fused. Suppose the observer's eye is at a minimum distance and adjusted for parallel rays, but upon exerting his accommodation the first set of vessels becomes dim and the second set clear; he is manifestly dealing Avith a case of simple hypermetropic astigmatism. But if, under the same conditions, he cannot by any accommo- dative effort obtain a distinct image of the second set of vessels, the case is one of simple myopic astigmatism. In a case of compound hypermetropic astigmatism, if the observer's eye is at a minimum distance and adjust- ed for parallel rays, he can only see the vessels or other details by exerting his accommodative poAver; and dif- ferent degrees of accommodation will be required for successively focussing vessels running in the direction of different meridians. IIS THEORY AND PRACTICAL USES. 107 Astigmatism may also be detected by the indirect method; for if the lens is held at its principal length from the eye and then gradually moved nearer, the disc appears more and more elongated in one diameter; but if instead, the lens is gradually withdrawn, the disc appears elongated in the diameter at right angles to the first. Thinning and increased curvature of the cornea sometimes occurs while its substance remains transpar- ent. This condition is knoAvn as conical cornea. A cone-shaped prominence involves a part or the Avhole of the cornea. Its summit is always blunt and its sides vary much in height and abruptness. This can usually be seen with the unaided eye. When simple inspec- tion or the oblique illumination fails to detect an eleva- tion of this kind, the Ophthalmoscope may be employed. Using only the mirror and reflecting the light upon the eye from different angles, the side of the cone opposite the light will appear shaded or darkened. But such a test will not be needed except in slight degrees of the affection. By the indirect method of examination, if the lens is moved from side to side, portions of the image of the fundus will appear much distorted and rapidly change shape Avith the movements of the lens. 108 THE OPHTHALMOSCOPE; TABLE SHOWING THE DIFFERENTIAL DIAGNOSIS OF THE REFRACTION OF THE EYE. In an eye that is The optic axis Far vision is im- proved Hypermetropic, (Symbol H.) Emmetropic, (Symbol E.) Myopic, (Symbol M.) Is shorter than that of the nor-mal eye. By convex glasses. Is normal. By no glasses. Is longer than that of the normal eye. By concave glass-es. APPEARANCES WHEN VIEWED WITH THE OPHTHALMOSCOPE-DIRECT METHOD. The image of fun- dus at some dis- tance from the eye, is The image moves with the obser- ver's head The position of the image seen is Close to the eye, the image of the fundus can be seen Smaller than nor- mal. In the same direc- tion. Behind the eye. With a convex lens, or without a lens, or with a concave lens. Normal. Without a lens, or with a concave lens. Larger than nor- mal. In a contrary di- rection. In front of the eye. With a concave lens only. APPEARANCES WHEN VIEWED WITH THE OPHTHALMOSCOPE-INDIRECT METHOD. If the lens is moved farther from the pa- tient's eye, the image The size of the image The image is best seen at a dis- tance of Becomes smaller. Is larger than normal. About 30 inches Does not change. Is normal. About 20 inches. Becomes larger. Is smaller than normal. About 12 inches. CHAPTER XL THE FUNDUS OF THE EYE. The consideration of some of the changes of the fun- dus of the eye in disease Avill occupy the closing pages. The plan of this treatise does not permit of introducing, to any extent, the etiology or attendant symptoms of any of the special diseases of the eye. My purpose Avill be accomplished if the rudiments of Ophthalmoscopy are made plain and the study of diseased appearances intelligently begun. The changes Avhich can be readily observed Avill be described; the chief Ophthalmoscopic appearances of the optic disc, the retina and the choroid in disease Avill be separately reviewed, and some practi- cal hints regarding the nature of the changes and how to look for them \villbe added. Their thorough eluci- dation should then be sought out in some of the larger works devoted to the eye. It may be Avell to remind the student that, oAving to the intimate relations of the structures at the fundus of the eye, he must not expect to often find marked altera- tions in one part Avithout more or less important changes in parts adjacent. In most cases Avhere symp- toms of disease exist which, directly or indirectly, may 110 THE OPHTHALMOSCOPE; be referred to the fundus, it is well to explore this portion of the eye in all directions taking the optic disc as the starting point. Very serious disorders may have their origin in the periphery as well as in the center or in other portions of the fundus, and the situation of any abnormal appearance should be carefully deter- mined. The location of any spot may be determined by noting its distance from the optic disc and at the same time considering the direction from Avhich we look into the patient's eye. Elevations and depressions of the -surface at any point must not only be recognized but must be distinguished from each other. With the binocular Ophthalmoscope alterations in surface level appear in their true charac- ters, but the case is different with the monocular instru- ment. With the latter, attention must be directed to the course and appearance of the vessels; for as these ascend or descend from one level to another they de- scribe a more or less acute curve. A slight alteration in surface level will cause a very slightly perceptible curve; but on the other hand, the curve may be so abrupt and extensive as to hide portions of the ves- sels from vieAV. If the details of a portion of the fundus are clearly focussed Avhile those of closely adjacent portions are ITS THEORY AND PRACTICAL USES. Ill indistinct, Ave may suspect a relative difference in sur- face level unless the appearance can be accounted for by slight opacities, astigmatism or otherAvise. To ascertain whether a part is elevated or depressed, apply the tests for hypermetropia and myopia respec- tively. An elevated portion of the fundus will lie Avith- in the principal focus of the dioptric media and there- fore be hypermetropic. The floor of a depression lies beyond the principal focus of the dioptric media and is myopic. By the direct method an image of each con- dition can be seen at a distance, the first erect and the second inverted. An elevation or a depression in the fundus oculi can be measured by mathematical calcula- tions based upon accurate estimates of the states of refraction of the summit and base of an elevation, and the margin and bottom of a depression. Those desiring, in a work of this kind, to learn some- thing of the nature of these calculations, Avill find in the last chapter a description of those most useful and simplest. The Optic Disc—The optic disc, or papilla, is fre- quently the seat of pathological changes, and its appear- ance differs much in the various affections. To know what is normal is to knoAV Avhat is abnormal, but the latter by no means implies a knoAvledge of the true significance of each change observed. The changes 112 THE OPHTHALMOSCOPE ; which oftenest occur together, make up Avell established conditions, or those which have received definite names; and the following conditions of the disc will be re- viewed and their distinguishing appearances described: viz. hyperemia, inflammation, ansemia, atrophy, ex- cavations and pigmentation. Hyperoemia.—This accompanies hyperemia of the optic nerve, and if confined to one eye, an advantage may be gained by comparison Avith the healthy eye (a fact not to be forgotten in other disorders). The disc becomes much reddened, its vessels are fuller and its margins not clearly defined owing to a hazi- ness Avhich extends over into the retina. The vessels of the retina are generally more or less enlarged, and often the Avhole fundus, including the disc, is of a uniform red or scarlet hue. In the latter case, the position of the center of the disc can be determined only by the position of the central vessels. Inflammation.—In optic neuritis, or inflammation of the nerve, the phenomena in the disc differ Avith the origin of the disease and its successive stages; but in the earlier stages the folloAving symptoms generally present themselves: The disc appears larger than in health and is red, swollen and somewhat cedematous. Its surface is convex instead of concave, its margin hazy and dimly defined. The appearance of the surface and ITS THEORY AND PRACTICAL USES. 113 margin of the disc is often described as "wooly", and is due to hypertrophy of its connective tissue. The ves- sels from the retina cannot be traced beyond its mar- gin, and their exit from the eye is frequently lost to vieAV. New vessels often become developed upon the surface of the papilla, and not unfrequently its surface and vicinity are the seat of numerous blood extravasa- tions ; both of Avhich causes render it very red and vas- cular. Tlie disc is prominently elevated and can be seen at some distance from the eye in the erect image. Owing to the firm and unyielding nature of the scleral ring Avhich encloses the nerve's extremity, the SAVollen and infiltrated nerve presses upon its own ves- sels and obstructs the circulation. As a result the retinal veins are more or less engorged, dark and tor- tuous, while the arteries are much contracted and at times scarcely distinguishable. Severe cases of optic neuritis are usually followed by more or less complete atrophy of the papilla and nerve, and this constitutes the later stages. (See Atrophy). Ancemia.—In anaemia both eyes are equally affected, each disc being unnaturally Avhite. The retina and choroid are also wanting in color. The eyes do not light up well. The general state of health in Avhich the patient is found helps to explain the anaemic state of his eves. 8 114 THE OPHTHALMOSCOPE ; The paleness of anaemia of the disc may be dis- tinguished from the paleness of atrophy by observing the following facts. In anaemia the fundus also is pale, but in atrophy it remains red because the choroidal ves- sels are normal in color. The paleness of the anaemic disc is not so striking as that of the atrophic, owing to its lack of contrast with the surrounding fundus. In all stages of anaemia, although the amount of blood is small in both the central arteries and veins, these ves- sels can be distinguished from each other. In the earlier weeks of atrophy the central veins are dilated and the arteries small; but later, both sets of vessels are reduced in size and number and finally become un- distinguishable from each other. It not unfrequently happens that no vessels can be traced over the white e xpanse of an atrophied disc. Perhaps a single artery or vein may remain, though it is generally destitute of branches. Atrophy.—Two classes of atrophy of the optic papilla are usually described, viz., the primary or progressive, and the consecutive. The appearances of the disc in atrophy may be enumerated as unnatural whiteness, decrease in calibre of the retinal vessels (the veins diminishing in size somewhat later than the arteries) and a peculiar excavation of the disc itself. The character of this excavation is further described ITS THEORY AND PRACTICAL USES. 115 and illustrated under Excavations, Avhich see. Some- times the Avhiteness is very great, and in other cases the color is bluish-white. The small nutrient vessels upon the surface have generally disappeared, and this aids in producing its unnatural whiteness. The latter is especially marked in cases of primary atrophy in which the outlines of the disc though sometimes irreo-- ular, are clearly defined. Atrophy consecutive upon optic neuritis is usually for a long time distinguishable from other kinds. The papilla remains SAVollen, and its outline indistinct. Its color is of rather a dull grayish-Avhite; but after a time distinctions become lost, and it assumes the same ap- pearance as the other varieties. In most cases of atrophy of the disc both eyes are affected, but not always to an equal extent. Cupping or Excavation.—This occurs in three varie- ties, known respectively as the physiological, the atrophic, and the glaucomatous cups. The first, or physiological cup, has already been mentioned as a congenital excavation. It never in- volves the whole disc, is usually very small and shalloAv and generally confined to the central portion, though quite often displaced. The Avails are in most cases slightly inclined from the center to a higher level. Exceptionally they are 116 1HE OPHTHALMOSCOPE ; steep or irregular, or the cup may be funnel-shaped. As the retinal vessels enter the disc, the curve more or less acutely as they pass the margins of the cup. The Avhole fundus moreover looks healthy and cheerful, and there are none of the symptoms accompanying the other diseases. Fig. 22 sIioavs a sectional vieAV of the nerve and disc, giving the form of the phys- iological excavation. In the atropine cup there is loss of nerve fibers, blood vessels, and sometimes connective tissue. The blood vessels are not usu- ally all lost, but those Avhich remain are altered in size and appearance as before described. The excavation is shallow, but involves the whole surface of the disc. It is also deepest at the center. In the beginning of atro- phy the whiteness is very bright, and occupies a portion of the disc near its center. Later, this Avhiteness ex- tends and occupies the whole surface of the disc quite up to the sclerotic ring, and the latter stands out very distinctly. The ultimate color of the disc is apt to be bluish or grayish white. The shallowness of the ex- cavation and its gradual inclination from center to edge cause no very marked curve or displacement of those vessels Avhich remain. They pass over its edge Avith ITS THEORY AND PRACTICAL USES. 117 little or no appreciable curve, and no part of them is lost to view. Fig. 2?> is a sectional view of the atrophied disc, shoAving its peculiar excavation. The glaucomatous cup is usu- ally very deep, and occupies the Avhole surface of the disc. In its early stages the Avails may be steep, straight and only mod- erately deep, but as the disease progresses the cavity deepens and the edges of the disc overhang its sides. In the first case the continuity of the central vessels may be -traced, though they necessarily describe a very sharp curve on passing the edge; but when the sides become excavated laterally, parts of these vessels are lost to view. Vessels from the retina upon reaching the margin seem to abruptly break off, but remnants , of them may again be dimly seen near the center of the floor of the excavation. A shadow surrounds theporus opticus in the form of a ring and changes with the movements of the Oph- thalmoscope. This shadow is cast by the walls of the excavation and Avas formerly the cause of an optical illusion, and cupped discs Avere regarded as prominent ones. Deeply cupped discs have a mottled appearance, the result of atrophic changes and the manner in which 118 "UK ophthalmoscope; the light falls upon them; the usual color is gray or grayish-white; it may be greenish or even very Avhite. Another characteristic appearance in the glaucoma- tous cup is the so-called parallax of glaucoma. This is made apparent while using the indirect method of ex- amination and slightly moving the objective from side to side. As the objective is moved, both the floor and the margin of the excavation move too, but the latter much more rapidly than the former; and it requires no great movement of the lens to cause the margin to move some distance across the bottom of the excavation. Arterial pulsation so often noticeable in glaucoma is another distinguishing point, but the characteristic displacement of the vessels, the abrupt sides of the cavity, and the other points al- ready described, can hardly fail to show the nature of the glau- comatous cup. Partial cupping of the disc has been sometimes observed in glaucoma. It is recognized by the same marks as the other forms. Fig. 24 is a sectional view giving the general shape of the glaucomatous excavation. Pigmentation.—It is ndt unusual to find quite a de- posit of pigment along the edge of the optic disc, but very rarely does pigment become deposited within the ITS THEORY AND PRACTICAL USES. 119 limits of the disc itself. Cases have been reported, hoAvever, in Avhich marked pigmentation of the disc occurred. This abnormal change has usually followed some severe accident to the eye, and is due to the es- cape of coloring matter from the blood. CHAPTER XII. 1HE FUNDUS OF THE EYE, CONTINUED. The Retina.—Affections of the retina Avhich have been described in ophthalmic literature are somewhat numerous. The following will be especially consid- ered: anaemia, hyperemia, inflammation, atrophy, de- tachment, tumors and embolism of the central artery. Anaemia and hyperaemia of the retina have been considered under the same affections of the disc with which they are associated. Inflammation of the lletina {Retinitis).—In most cases of retinitis the disc is inflamed also. In all cases of optic neuritis of any extent, the retina is involved. The concurrence of inflammation in both of these structures is known as neuro-retinitis. But affections of the retina are best described separately from those of the disc. The varities of retinitis will be examined separately from each other. Acute Parenchymatous Retinitis.—This variety pre- sents the folloAving ophthalmoscopic appearances: The fundus of the eye is uniformly scarlet and the out- lines of the optic disc lost. The central artery may remain normal but the veins are enlarged and unusually ITS THEORY AND PRACTICAL USES. 121 tortuous. Blood extravasations of varying form and extent are usually scattered over the expanse of the retina. An effusion of serum or lymph renders the retina more or less swollen and cedematous. There is a hazy look about the fundus, in most cases, OAving to the retinal infiltration. If the disease assumes a more chronic form, the in- flammatory exudation causes the disc, as Avell as the surrounding fundus, to look opaque, and the character of the exudation determines the color of the opacity. An opacity resulting from serous effusion is pale and of a grayish or grayish-pink color. An exudation of lymph causes an opacity Avhich is nearly Avhite. If the exudation occupies the external retinal layers, the retinal vessels Avill not be obscured; if the internal retinal layers are involved the vessels will be hidden to an extent depending upon the nature and size of the exudation. Hyalitis, or inflammation (with sequent haziness) of the vitreous body, is an accompaniment of acute retini- tis, especially if the internal layers are affected; this may obscure to a considerable extent the real ap- pearance of the retina. The spots of blood extrava- sation vary in color, size and appearance Avith the depth at which they are situated, the length of time they have existed, and whether they originated 122 THE OPHTHALMOSCOPE; from the arteries or from the veins. Farther space will be devoted to a description of these under retinitis apo- plectica. Inflammatory exudations may occupy the whole or a part of the retina, and may be scattered about in spots or in clusters of spots. Serous Retinitis.—Serous retinitis is not easily recog- nizable Avith the Ophthalmoscope. It is characterized by a delicate, uniform, bluish-gray or greenish opacity, which appears like a cloud over the surface of the retina. The infiltration of serum is usually most observable about the disc, and gradually shades off toward the periphery of the retina. The periphery may be entirely free from any infiltration. On account of the thinness of the retina at the macula lutea the opacity at this spot is less marked; as a result there is an apparent increase of redness at this point, owing to the reflection from the choroidal vessels. The retinal arteries are normal while the veins are usually congested, dark and twisted in their course. Retinitis Albuminuria {Nephritic Retinitis).— This variety of retinitis has been repeatedly observed during the progress of Bright's disease of the kidneys, and often precedes, or is recognized before any of the other symp- toms of the latter malady are apparent. The patho- logical appearances of the retina are thought by some authors to be constant and peculiar; but before the ITS THEORY AND PRACTICAL USES. 123 disease is fully developed the changes which are ob- servable are all included under the forms of inflamma- tion already described. The disc is hyperasmic and its outline indistinct. There is serous infiltration in the vicinity of the disc and this occupies quite a portion of the surrounding retina. The arteries are normal at first, and the veins larger, darker and more tortuous than usual. As the disease advances the above symp- toms become more marked and the optic disc may even become swollen and prominent. Now the character- istics of the disease begin to appear. Haemorrhages are the first and these occur early in many cases. Some- times they are about the first thing noticed and the most usual position is in the vicinity of the disc and macula lutea. Small Avhitish spots (sometimes yellow or gray) begin to form in the retina around the disc. These develop in size and number and finally coalesce into one large patch, or, as is more usual, form a broad white belt around the disc. This belt is usually sepa- rated from the disc by a space which is occupied by grayish infiltration. At the same time whitish dots, or small starlike figures are noticed in the region of the macula lutea. These also may run together and perhaps join the belt. These spots around the macula lutea, together with 124 THE OPHTHALMOSCOPE; the whitish belt surrounding the disc, are the most characteristic symptoms of this form of retinitis. It is often possible to discover Bright's disease before much evidence of it can be gathered from the urine. In cases where it is least expected, the oculist has some- times to announce to the patient the true nature of his malady, and confirm his diagnosis by an examination of the urine. The spots Avhich appear in the region of the optic disc and the yellow spot are due to fatty degeneration of blood and of connective tissue. All of the symp- toms enumerated differ much in character and degree in individual cases. Similar spots and marks are some- times present in other forms of retinitis, especially in that form due to constitutional syphilis; but the spots are much paler in the other forms, and those in the region of the macula lutea are never star-like as in the nephritic varity. The general history of the case should confirm the diagnosis. Retinitis Pigmentosa.— In this form of disease not only the retina but often the choroid suffers in a pecu- liar manner. The appearance of a well developed case cannot well be mistaken for anything else. The dis- ease is said to be congenital, or rather is due to con- genital predisposition, and owing to its manner of origin and sIoav progress it may not be recognized for years. ITS THEORY AND PRACTICAL USES. 125 I have already mentioned physiological pigmentation around the optic disc and pathological pigmentation of the disc itself. In exceptional cases, pigment may be deposited in the retina in the course of optic neuritis; but none of these constitute the disease in question. Retinitis pigmentosa usually makes its beginning in the periphery of the fundus upon the nasal side and then extends gradually around, all the Avhile advancing towards the posterior pole. It is characterized by Arari- ously shaped black spots of pigment irregularly dis- posed or gathered into clusters. Some of these spots are round or oval, some have rough jagged edges and others (usually the larger ones) have long narrow pro- cesses radiating from them. Often the spots seem dis- posed to follow the course of the bloodvessels which at times have black streaks or lines side by side Avith them. The last stages of the disease are characterized by atro- phy of the retina and optic nerve, together Avith changes in the choroid. The latter consist in loss of epithelium in places, exposing the vessels and thus forming light patches Avhich are usually fringed Avith dark pigment. If the choroidal structure becomes atrophied, the Avhite sclerotic is seen shining through in Avhitish patches. The vitreous seldom becomes affected. The disease is generally binocular. Syphilitic Retinitis.—As the name implies, this form 126 THE OPHTHALMOSCOPE ; of inflammation occurs in the course of constitutional syphilis. It so frequently closely resembles other forms of retinitis that the patient's history must aid largely in deciding its nature. Spots and opacities resembling those described under albuminuric retinitis form in the region of the yellow spot and optic disc, but they are of a duller hue and less persistent. They come and go, and require only a few days for new ones to appear and old ones to disappear. The choroid and iris are apt to become implicated in this inflammation and it atrophy of the choroid follows, changes similar to those described under retinitis pig- mentosa take place. Retinitis Leuccemia is a very rare disease which some- times accompanies a disease of the spleen and lymph- atic glands. The fundus has a pale orange-red color if examined by diffuse daylight received through a hole in the closed window shutter. The papilla is pale and the retina about it clouded. The retinal vessels, nota- bly the veins, are peculiarly pale. The cloudiness of the retina is striated. Small, irregular, whitish spots are seen in the region of the yellow spot, and these are more numerous towards the periphery of the retina. Sometimes these spots are large and round and fringed with red. Effusions of blood are scattered over the fundus irregularly. IIS THEORY AND PRACTICAL USES. 127 Retinitis Apoplcctica.—Haemorrhages into the retina are not often absent in any marked case of retinitis, but where the tendency to extravasation of blood is very great and the patient is one in whom some dis- turbance of the general circulation is known to exist, the term retinitis apoplectica is applicable. Haemor- rhages into the retina seem governed by no rule as to extent, location or number. They may occur in the outer or in the inner layers. They may lie between the retina and the choroid or may extend inwards and burst through into the vitreous humor. Their location may be such as to partially or completely obscure the retinal vesssls from view or they may lie directly behind these vessels, the latter being seen to pass directly over them. In this form of disease there is usually very little de- structive change in the retina itself OAving to the slight nature of the infiltration, but the recurrence of the trouble is to be expected and it may lead to degenera- tion of the retina and optic nerve. The appearance of an effusion of blood into the retina, if seen early, is bright red. In all cases haemorrhages appear much darker than the surrounding fundus and they retain their color a long time. If absorption takes place the spots gradually assume a brighter color, break up and disappear. If, as sometimes happens, they undergo. 128 THE OPHTHALMOSCOPE ; fatty or pigmentary changes, black spots are the result, and these are more or less permanent. Atrophy of the Retina is a sequel to many inflamma- tions of the inner parts of the eye. It may involve the whole or only a part of the retinal structure. Atrophy of the retina and atrophy of the optic nerve always go together. The central bloodvessels are much attenu- ated and reduced in number or else quite lost. The in- creased thinness of the letina Avith its loss ot reflection renders it very little obstruction to a distinct view of the choroid. Spots of exudation sometimes remain a long time in the retinal tissue, or pigment may become deposited along the course of some of the remaining bloodvessels. Detachment of (he Retina means a separation of the retina from the choroid, and may begin at any point; it may remain small or extend in all directions. The lower half is most often the seat of a detachment. The appearances of a detached portion, if large, are those of a loose folding surface bulging more or less forwards into the vitreous humor, and trembling with each move- ment of the eye. Its vessels are usually darker than those of the surrounding fundus and there is more or less cloudiness in the part. Sometimes the vessels can be traced in their tortuous course over the folds; but more often their continuity seems broken. ITS THEORY AND PRACTICAL USES. 129 Small detachments are more difficult to see than large ones; their presence may be suspected if slight opaci- ties are noticed at any point, together Avith a curving of the vessels passing over them. Tumors of the Retina need but a brief notice here. They are classed either as glioma or as glio-sarcoma, and they present the following ophthalmoscopic symp- toms if seen very early in their course; a small pro- trusion from the surface of the retina at some point Avith some effusion about it, and perhaps some enlarge- ment of the surrounding vessels. As this is a disease of childhood, it is seldom seen until a later stage than above described and the first thing usually noticed is a bright shining yellowish re- flection from the fundus of the eye, seen by the un- aided eye in a favorable light, or by the oblique illu- mination. With the Ophthalmoscope the growth can be accurately examined so long as the media remain clear. It usually appears nodular and vascular upon its surface, and in color it is either orange, yellow or whitish. The reflection from such an eye is usually similar to that from a cat's eye seen in the darkened room. The further development of the tumor is that of increased growth and protrusion until it occupies the whole surface of the retina, and finally the Avhole eye. 9 130 THE OPHTHALMOSCOPE; Iii Fig. 25 may be seen an illustration of a case of glioma retinal in a very advanced stage. It is a case which occurred in the practice of the author, and, as is frequent in such cases, came into his hands at a late day. ——~^ ____ 17 10 8 3 — 3 — 3 — 48 20 ,4 It 4 — 4 — 4 - 33 20 14 U 6 — 4S n, >■ «•• L* I. " " " .. " 142 the ophthalmoscope; opening in the first disc Avhich may be filled by any glass he desires. An astigmatic observer should have an appropriate glass additionally inserted into each disc in the same manner as an ametropic observer, and in case his astigmatism be compound, the additional glass should, of course, correct both his astigmatism and his ametropia. The second object of Ophthalmoscopic Optometry, the measurement of elevations and depressions in the fundus oculi, is accomplished by determining in the erect image the states of refraction of the crest and the basis of an elevation, or the margin and the bottom of a depression. Since the optical apparatus in one and the same eye remains unchanged during the examina- tion, the differences in the state of refraction of differ- ent parts in the fundus may be found by calculation. I described this method of ophthalmoscopic determination of the relief of the background of the eye at the Con- gres International a" Ophthalmologic, in Paris, 1867, (see the Compte-Rendu of that meeting, p. 165, etc.), and published a table for that purpose in my treatise on the Intra-ocular Tumors (p. 106, English trans- lation). L. Mauthner, too, described the same method "n his book on Ophthalmoscopy (1868, p. 206, etc.), and E. G. Loring, in an excellent paper; Determina- tion of the Optical Condition of the Eye by the Oph- ITS THEORY AND PRACTICAL USES. 143 thahnoscope, with a new modification of the Instrument for that purpose, Am. Journ. of the Medical Sciences. 1870, p. 323, etc. The method is, indeed, nothing but the ophthalmo- scopic application of the determination of the length of the ocular axis from knoAvn degrees of ametropia. The calculation is as follows: If Ave apply the gen- i'I F2 eral dioptric formula----1- — = 1 to the eve, and em- A h plo}- for the anterior and posterior principal focal lengths F\ and Fz, the values Fi = 15 mm. and F2 = 20 mm., according to Listing's reduced eye, Ave obtain, by ophthalmoscopic observation two conjugate focal lengths, fi and fz. The luminous object is the back- ground of the eye, its image is seen with the Oph- thalmoscope, and its position, respecting its conjugate focal distance, is determined by the correcting lens. If Ave call the conjugate focal distance of the image/i, and the conjugate focal distance of the luminous object f2, Ave determine fx by ophthalmoscopic observation, and find^s by calculation. The above-mentioned general dioptric formula, Fx F2 A f* 144 THE OPHTHALMOSCOPE; transforms into ft Ft /i = ft-F* If we deduct FY from both sides of the equation, namely, fali fi — F!=--------Fi fa — F2 and reduce this expression, we obtain Fx F2 fi — Fi =----- f2—E2 /i — F\ in algebraic language signifies the distance be- tween the first conjugate and first principal focal points, and fa—ffl means geometrically the distance from the second conjugate to the second principal focal point. Let us put f\ — F\ = I1, and f2 — F%= te, the above formula reads: ll h =F\ E\. This formula and its deductions are taken from Helmholtz's Physiologische Optik, p. 49. For the con- venience of calculation we Avrite it: F F2 h =----- fi—F,. because f\ changes with every auxiliary glass. f\, as we have seen above, does not exactly represent the priucipal focal length of the auxiliary glass, but its ITS THEORY AMD PRACTICAL USES. 145 distance from the eye has to be added in eases of myo- pia and deducted in cases of hyperopia. This distance may be reduced to 20 millimetres. In examining, in the erect image, the patient's right eye with my right eye, and his left Avith my left, the mirror can, Avithout inconvenience, be held so near the patient's eye that the auxiliary lens is 14 to 20 mm. distant from the first principal plane, that is, the middle of the anterior chamber of the patient. The mirror then touches the patient's eyebroAV, and thus is invariably at the same distance from the examined eye, whereas this distance is apt to vary in different observations, if the mirror has no point of rest on the patient's as Avell as on the physician's orbital margins. If the mirror is held at some distance from the eye under examination, this distance has to be measured for every available observa- tion ; but if one edge of the mirror touches the brow of the patient, the distance of the correcting glass from the anterior principal plane of the examined eye may with sufficient accuracy be assumed to measure 20 mm., which quantity has been used in the calculation of the subsequent table. I may still remark that, if h is found positive, it lies behind the posterior principal focal plane; if negative, it lies in front of it. As the table is intended to be a help for practice, the first column indicates the auxil- 10 146 THE OPHTHALMOSCOPE ; iary, i. e., correcting glass, with which the determination is made, but h is computed from the real degree of ametropia, that is as approximately as it can be deter- mined Avith the lenses which, thus far, are at our disposition, and, as is known, are all more highly num- bered than their focal lengths would indicate; for instance, Xo. 36 is in reality 33-}: 20 is 18£, 14 is 13, 9 is 8J, etc. The table on page 148 Avill make it easy to measure the height of elevations, and the depth of depressions in the background of the eye. If the eye be emmetropic, the quantity corresponding to each auxiliary glass at once indicates in millimetres the elevation or depression of a diseased part. If the eye be hyperopic or myopic, the degree of II or M may first be determined, and afterward the refractive condition of the part, the elevation or depression of Avhich Ave Avant to measure. The difference in the refractive conditions of these two determinations refers to two points, situated on the antero-posterior diameter of the globe. Their distance from each other can easily be computed by referring to the table. For instance, an eye, the fundus of Avhich is seen with -4- 24 is affected with a small intra-ocular tumor, the crest of which is seen Avith -f- 6. + G cor- responds to a shortening of the ocular axis of 1.91 mm., + 24 to a shortening of 0.47. By subtraction we ITS THEORY AND PRACTICAL USES. 147 obtain 1.44 mm. as the height of the tumor. If the eye had shown M 1-24 instead of H 1-24, and the crest of the tumor had shown as before, H 1-6, the elonga- tion of the optical axis corresponding to M 1-24, viz., 0.46 mm. should have been added to 1.91. Then the height of the tumor Avould have been 2.37 mm. This sort of calculation is so easy to understand that I need give no other examples. The tAvo sets of glasses, however, enable us to determine elevations or depres- sions Avithout resorting to any calculation, by simply referring to the foregoing table. We determine first either the greatest elevation or the greatest depression of that portion of the fundus the height or depth of Avhich Ave want to ascertain. For instance, the crest of a tumor, with relaxed accommodation, is seen Avith -4- 6. We leave -f- 6 in its position behind the aper- ture of the mirror, and diminish its effect by placing concave glasses of increasing strength over it until Ave see distinctly the basis of the tumor, i. e., the fundus ocidi. Suppose this is the case with — 8, then it is clear that the eye is hyperopic. Looking up the shortening Avhich corresponds to -f- =------. The h—Fy values of F\ and F2 are derived from Helmholtz's and my own measurements of the radius of curvature of the cornea. They are I = 22J) mm.; II = 30.3 mm. * See page 141. SPECTACLES; AND HOW TO CHOOSE THEM. By C. II. Vilas. M. A., M. D., Professor of Diseases of the Eye and Ear in Uie Hahnemann Medical College and Hospital, Chicago. i2mo. pp. 160. Cloth, $1.00. In a clear and comprehensive manner this volume treats of a mist impor- tant subject, concerning which far too many erroneous and danger >us notions prevail. Its aim is to disseminate the latest discoveries and prevent the common haphazird custom of choosing spectacles, a custom so often disastrous to \ isiou or productive of discomfort. The author points out how, within a comparatively recent period, what was once veiled in mystery, has attained a sure place among the sciences; how the knowledge of the proper construction, adaptation, and uses of spectacles h is grown to ureat proportions, and has led to a revolution in the treatment of eye affections. Many popular delusions will be dispelled by reading this book. All the new and useful cases of trial lenses are described and illustrated and their respective merits and demerits are poiuted out. Among other good points, it is shown how the low prices at which a good set of trial lenses can be obtained, will enable the physician in general practice to give attention to the fitting of spectacles, und to treating nrdina-y defects of the vision, thus preventing the frauds so often practiced by itinerant venders. The author's well known accomplishments in this department of science, have eminently prepared him to skillfully treat so important a subject. The work is finely illustrated and full of practical hints. OPINIONS OF TT?E PRESS. Never before to our knowledge, has the subject been expi lined in so lucid and at the same time entertaining a manner, as by Professor Vilas in this little monograph.—Quarterly Bulletin. Were the essay especially designed to give a hint to general practitioners as to how little they re illy know, or claim to know, of the scientific selec- tion of spectacles and faintly indicated to them how much harm in i.v result from a blunder in this matter, the samecould not have been more skillfully written. — The United, States Medical Investigator. A very interesting and instructive book, not on\v for the general practi- tioner, for whom it is especially designed, but also far laymen, technicalities and obscure terms being avoided. Its aim is to prevent the too common haphazard and often injurious custom of choosing one's own spectacles, or trusting to unprincipled or ignorant yenders. Dr. Vilas writes clearly and forcibly, and conveys in a pleasant manner much practical information. The dollar for it will be well spent. — New England, Medical Gazette. This book is wr.tten in a very agreeable, chatty style, and deals with a rather dry subject in a manner which makes the volume very pleasant read- ing, it contains much that physicians should underhand, so that they may advice wisely, and, if necessary, protect their clients against the impjsi- tions put upon them by unqualified dealers in eye-glasse3. The piper is excellent, the typ » clear, the volume is profusely illustrated, and the price only one dollar.—The Weekly Counselor. It will prove especially useful to the general practitioner who cannot spare time to investigate larger works.—Hahnemannian Monthly. A moch needed addition to our literature. The author has, in his brief exposition, struck a happy m >dium between the strictly technical and the p >pular style. It is profusely illustrated and will repay students and physi- cians who carefully study its p iges.— Medical Advance. "This is a very pi >asant semi-popular treatise on the different kinds of glasses required to aid the sight, and the conditions which call for them. It tells everything which an intelligent layman, or even an ordinary practi- tioner need know about the anomalies of vision and their correction. It would, we should think, be especially valuable to opticians in towns where no oculist is resident; and if we know of any such, we could hardlv do them a greater service than by bringing it to their knowledge."—British. Journal of Humes ipatny. DUNCAN BROTHERS, 131 <& 133 S. Clark street, CHICAGO. A TREATISE ON THE Decline of Manhood : ITS C-A^TJS-EDS, And the Best Means of Preventing their Effects and of Bringing about a Restoration to Health. By A. E. SMALL, A. M., M. D., President of Hahnemann Medical College and Hospital. Professor of the Principles and Practice of Medicine, etc. This work treats a delicate topic in a dignified and scientific manner. " A popular treatise, pure and helpful, on masturbation in both sexes, spermatorrhoea, the sexual relation in marriage, etc."—New Engl ind Medi- cal Gazette. "The Doctor discusses the question in a plain and sensible manner, and exhibits the causes which lead to the deplorable results so freq ently met with among young men. Parents as well as childien who are capable of thinking for themselves, would find in this little work many valuable sug- gestions, since the writer even goes so far as to suggest a line of treatment for those who are suffering from premature decay."—Saturday Evening Herald. "This is a subject to which most physicians have given a good deal of attention, and have had more or less of success in the management of the cases that have come to them. Perhaps no work will be more welcome to the profession—filling, as it does, a most important vacancy in medical lit- erature with its wise counsel. Aside from Acton on the Reproductive Organs, there is little or no reference to sexual weakness in its various phases, in any professional standard work. This work in many ways is a most healthy one to put into the hands of young men, and it will tend to save them from the grasp of quacks whose flaming advertisements tend to frighten and decoy their deluded victims. The work is dignified in tone and full of practical suggestions:—United States Medical Investigator. Sent free on receipt of price, $1.00. DUNCAN BROTHERS, Publishers, 131 <& 133 S. Clark Street, CHICAGO. THE Diseases of Women. By E. LUDLAM, M. D., Professor of the Medical and Surgieal Diseases of Women and Obstetrics in Hahnemann Medical College and Hospital, Chicago. 1 Volume. 1029 Pages. Fifth Edition. Revised and Rewritten. This work is entirely remodelled, rewritten, and arranged on a systematic and scientific basis. Part I. considers the General Pathology and Physical Diagno- sis of Diseases of Women. Part II. treats of the Diseases of Puberty. Part III. Disorders of Menstruation. Part IV. The Diseases of Pregnancy. Part V. Post Peurpenil Diseases. Pa*t VI. The Diseases of Lactation. Part VII. Diseases of the Climacteric. Part VIII. General Diseases of Women. Part IX. Surgical Diseases of Women. The v hole makes a magnificent volume, profusely illustrated and hand- somely printed and bound—the largest, latest, and best book on Diseases of Women, in fact pronounced the finest work on this specialty. " Book just arrived ; it is more thvn first-class."—J. G. Gilchrist, M. D. Price in Cloth, $6.00 ; Leather, $7.00. DUNCAN BROTHERS, 131 & 133 S. Clark Street, CHICAGO. HOMCEOPATHIC THERAPEUTICS, AS APPLIED TO OBSTETRICS. By SHELDON LEAVITT, M.D., Professor of Physiology and Clinical Midwifery in Hahnemann Medical College and Hospital, Chicago: This work, by a clinical teacher on this branch, meets a want that has been long felt by those who meet peculiar symptoms in obstetrics. The study of remedies from a disease point of view is valuable, and this work will fill an important field in our literature. Dr. D. S. Smith, says: "I have critically read the 'Therapeutics of Obstet- rics,' and find it a very useful and convenient little book of reference, and take pleasure in commending it to the profession, more especially to stu- dents, who will not fail to appreciate its merits." I have examined the book, "Therapeutics of Obstetrics," and am very much pleased with it. It seems to me that it will prove to be of great value to the busy practitioner ; and I know of no olher work from which one can gain' as much information in the same time on the choice of a remedy in any obstetrical emergency. H. P. Skiles, M. D. This new advocate for professional favor claims that, only "the most characteristic features of a limited number of remedies, and those only, are embraced" in its design. In pursuance of this object, there is given the condensed symtomatology of ninety odd remedies, with a repertory. The indications for the remedies are short but in the main good; the repertory will be found especially useful. This brochure will be of service to those who are in the habit of searching for the similimum; to all such we recom- mend it.—Homoeopathic Physician. Price, $1.00. DUNCAN BROTHERS, 131 <& 133 S. Clark St. CHICAGO. THE FEEDING AND MANAGEMENT OF Infants and Children. AND THE HOME TREATMENT OF THEIR DISEASES. By T. C. DUNCAN, M. D., President of the American P^edological Society. Consulting Phys- ician to the Chicago Foundlings' Home. Clinical Lecturer on Diseases op Children. Author of 'A Professional Treatise on the Diseases of Children" (2 large volumes). Editor of the United States Medical Investigator, etc., etc. What is said of it: Mrs. T. Wilce, President of the Mother's Society of Chicago, says : "It is the most instructive book for mothers and especially young mothers, that has come to my notice and I earnestly advise all prospective mothers to read it. Would to God that I had had such a book years ago." Mrs. H. E.Redeker of Kenosha, Wis., writes: "I think it isthe best work of the kind I have seen. I am glad that I shall have Dr. Duncan at hand ready to consult at any moment for I have the greatest confidence in all that he says. It is a book that it seems to me every mother would like to have." Dr. Edward Cranch, Secy, of the American Pasdological Society (com- posed of the leading physicians interested in Children's Diseases), says : " I have carefully examined the work and unhesitatingly pronounce it a most necessary book for all families. It ought to go into every intelligent household where the health of the little ones is valued." The Organon of London, Eng., says: •'Ptedologyis Dr. Duncan's Special- ite and we may be sure that what he writes on this subject contains many things worth reading. His Encyclopedia on Diseases of Infants and'Child- reti is a work for the profession ; this one is for the public, and a better work on the subject we do not remember to have seen. * * Every day rules for diet and regimen generally, are what the public should know, and without these the skill of the physician is daily thwarted ; in this respect Dr. Duncan has.performed his work admirably. The book is elegantly gotten up." A Valuable Elementary Book for Students. Price, Cloth, $2.00 ; Half Morocco, $2.75. DUNCAN BROTHERS, 131 <& 133 Clark Street, CHICAGO. HOW TO SEE WITH THE MICROSCOPE Useful Hints Connected with the Selection and Use of d?e Instrument; also Some Discussion of the Claims nU* Capacity of the Modern High-Angled Objec- tives, as Compared with those of Medium Aperture; with Instructions as to the Selection and Use of Amer- ican Object - Glasses of Wide Apertures. BV J. EDWARDS SMITH, M. D., PROFESSOR OF HISTOLOGY AND MICROSCOPY IN THE CLEVELAND (O.), HOS- PITAL COLLEGE ; CORRESPONDING MEMBER OF THE SAN FRAN- CISCO 5 THE DUNKIRK, 'ND ILLINOIS STATE MICRO- SCOPICAL SOCIETIES, ETC., ETC. ILLUSTRATED. The book abounds in practical hints that will be most highly appreciated by those of us who have had to work out for our- selves a great amount of experience at a great expense of pre- vious time (and often more precious eye-sight), and who know how serviceable a stray hint, or a word or two of suggestion has often proved. (Signed) Albert H. Tuttle. Ohio State University, February, 1880. Prof. Smith is well known as the most expert manipulator in this country, as regards objectives of wide aperture, and in this volume he gives, in a clear and practical manner, all the directions necessary to attain the surprising results which he has achieved. No microscopist who uses anything better than French triplets can afford to be without it.—From Jokn Phin, Esq., Editor Monthly Journal of Microscopy. There is at present no work in the English language which gives instruction in the best methods of handling the most modern microscopes and objectives. Prof. Smith's work will, therefore, till a long felt hiatus in our microscopical literature. —Journal ofMicroscop;/. I^BIay be ordered of any prominent bookseller, or will.be mailed direct to any one on receipt of price, $2.00. DUNCAN BROS. 131 and 133 S. Clark St., CHICAGO. " DOCTOR, Will T SHALL 1 LAIf A HAND BOOK OF DIET IN DISEASE. By CHAS. GATCHELL, M. D., Formerly Professor of Practice, University of Michigan. It is highly endorsed by the Profession and Medical Press. How often do we hear that same question. Doctor; what shall I eat? and though there are text-books enough on the Pathology and Trea tment of Disea-es, there is hardly ever a word found in them about the Hy giene in Disease. Gatchell as a t< acher, found out this want, and thus piobably originated this little treatise, for which we most heartily thank the author. We consider the recipes in it a little Materia Medica for itself, but follow instructions closely ; not quantity, but quality of food deserves our consideration. — North American Journal of Homoepathy. Milwaukee, Wis. "1 consider yourwork on "Diet in Disease" to be the most practical, and therefore ihe most useful, work on the subject with which I am acquainted. No ph\ sician should he without it; every mother should have it. It is in lise in many of the households in which I practice." C. C. Olmstead, M. D. President of the Wisconsin Homcepathic Medical Society. "This work isplain, practical and valuable. It is really a clinical guide on diet, and one the profession will find reliable and correct."— United. States Medical Investigator. "By far the best work on the subject in our literature. I find it of use every dav. I want one in every household in which I practice." Oak Park, III. F. G. Folsom, M. D. "Evidently much investigation, thought and carefulness have entered into the production of this work, and we believe it to be worthy a place in every household." — The Magnet. * * * "We have carefully examined the work and shall cheerfully recommend it for familv use. The directions as to what food and drinks, and modes of preparation are very judicious." * * * Kesp. Yours, Janesville, Wis. Dr. G. W. Chiitenden & Son, Professor Charles Gatchell's Manual of'Diet in Disease' is the best book on the subject for the people. It contains in 160 pages an astonishing amount of condensed information on a subject of great importance, and one but little understood. Its style is admirable, pithy and to the point. The book has no padding about it and deserves an immense sale. Samuel Potter. M. D., President, Milwaukee Aeademy of Medicine, Aathor of Index of Comparative Therapeutics, etc. etc. ^~ Sent free on receipt of price, $1 .OO. DUNCAN BROS., 131 & 133 S.Clark St. CHICAGO. THE NURSE; OR, HINTS ON THE CARE OF THE SICK; Including Mothers and Infants, and a Digest of Domestic Medicine. By CHARLES T. HARRIS, A.M., M.D. Elegantly bound in Cloth - - Price, 60 cents. "Every Nurse should have a copy." "Every Mother should possess this useful work." "It will not hurt physicians even to glance over the pages devoted to mothers and nurses, and this little treatise ought to become one of the tracts domiciled in every household."— North Am. Journal of Homoeopathy. This is a valuable volume to professional nurses and mothers, the natural nurses. The author strongly advocates the importance of intelligent, self- facrificiny: nurses. The instruction the book contains is cle >rly and con- scientiously given.—Boston Inventors & Manufacturers' Gazette. Such a work is very much needed. It is simply and clearly written, giv- ing hints on nil the points which a nurse ought to know. We cordially recommend this little work to the attention of mother- and nurses who will find it a valuable vade mecum.—Monthly Homoeopathic Review, London. A neatly printed, handsomely bound work of over a hundred pages, written with the endeavor, as stated in the preface, to make their scope "broad»enough to cover the wants of two classes; the conscientious and ambitious professional nurse, and the faithful and loving mother." The matter of the work, from the introduction'to the last page, seems well and carefully written and very sensible.—Ypsilanti Sentinel. It is written in simple and concise style and free from all technicalities, and abounds in valuable facts and directions to those who have health as well as to those who are called to nurse in the sick room. It is a book every mother could read with profit. Skilled and trained nurses are not a ways in reach, and the lives of those dear to the family are often imperiled by simple ignorance of what e\ery intelligent person should know. Good nursing, every intelligent physician will say, is of more value than drugs. The hand- some Hi tie volume should find its way into many homes, and by the intelligent observance of its rules, blessings alone will result.—The News. t=ST"May be ordered through your physician, or newsdealer, or will be sent to you direct on receipt of price. DUNCAN BROS., Publishers, 113 Madison and 131 &, 133 Clark St., Chicago. HOW to be PLUMP. OR TALKS ON PHYSIOLOGICAL FEEDING. BY T. C. DUNCAN, M.D., Author of a Professional Treatise on Diseases of Infants and Children and their Homoeopathic Treat- ment; Editor " United States Medical Investigator, etc. etc." Finely bound in Cloth - Price, SO Cents. It is an admirable work on hygiene, as far as *t relates to eating—Ohio. Farmer. These " Talks " have their own charm, for most of us like to be plump. —Women's Journal, Boston. Certainly all thin people should ponder well its suggestions and put them into practice.— Voice of Masonry. A brochure which many persons of lean inclinations will be glad to read and may be able to profit by.—Banner of Light. The little volume contains ntuch sensible professional advice upon healthy and morbid digestion, and the occasions of it.—Zion's Herald. The book is intended to indicate how anyone may become fat, fair and jolly, and a careful perusal affords proof that the author is fully conversant with his subject, and that he has done it full justice.—The Chicago Grocer. It is a common sense %rolume, that believes in rational and practical methods of preserving health, beautvand happiness. It is not a receipt book of impos-ibilities; it is a bright, genial book, that understands itself from first to last.—The Chicago Cosmopolitan. We do most warmly applaud its purpose, and especially commend its philos'>phyto theunnaturaliy lean, and still mor; to mothers in the training of delica e children whose physical stamina hardly equals that of a full- grown rye-stalk. Theirs is a leanness to be built up into steady strength and picturesque plumpness of limb and face.—The Standard. Chicago. Sept 18, 1878. The case referred toon page 45 of " How to be Plump" is our little boy, who was certainly rescued from death's door. This summer he began to run down again. After Dr. Dun< an had tried several medicines without benefit he -gain advised " inunction," and again with the same happy effect. The little fellow is now plump and well. Chakles Wales. ^^"May e ordered through your physician, or newsdealer, or will be sent direct on receipt of price. DUNCAN BEOS., Publishers, 113 Madison and 131 & 133 Clark St., Chicago. The NATURAL ABDOMINAL SUPPORT. It is the opinion of many eminent physicians that much of the dyspepsia, biliousness, constipation and other abdominal weaknesses are frequently due to the displacement of the bowels. The form droops, the back aches and all the internal orgaLS, lungs, heart, stomach, liver, etc., are dragged out of position, and the person looks, acts and feels " ail dragged out." To correct these various displacements the soft, elastic pliable Abdominal Support has been devised. The effect, when properly fitted and adjusted, is to keep the intestines in place, relieve the dragging and crowding upon the internal organs, and thereby enable the body to assume its natural form and graceful elasticity. Bloomington, Nov. 10,1879. Dr. T. C. Duncan :—A number of my patients have worn the Abdominal Support devised by you, and in every case it has given great satisfaction. One patient said she would not take $50 for hers if it could not be replaced. L. M. DAWSON. M. D. The support may be worn by men as well as ladies. Directions for Adjusting. The lower edge of the supportshouldfit the body along thegroins, under the clothing snugly. Buckle the two lower straps first— the lower one should be the tightest. The uuper strap should be loose unless the abdomen is pendulous. If the lower edge is not snug, draw up and tie the " gathering tapes." The support should not bind at any point, as that will weaken instead of strengthen. When worn to give support during pregnancy, a much larger size should be selected, and the upper strap should be quite loose, so as not to constrict. During the last month the support may be worn upside down. At such times a snug fitting waist should support the skirts. It is especially valuable after confinement. For corpulence or relaxed or weakened abdominal muscles, a special support should be ordered. This support, in ordinary cases, need not be worn all the time, but should be put on when taking a long walk, or ride, or when much on the feet. In all cases it is best to have a support made after exact measurement. \ Directions for Measurement. 1. Around the body an inch above the navel. 2. Around the body two inches below, or at full part. 3. Around the body oi a level with the bones in front. 4. Distance from bones in front to navel. 5. Distanre from bones in front over point of hip to middle of back on a level with the first measure- ment. Price: Ordinary style, $2.00; large or fancy, $2.50. May be ordered through your physician or direct. The money should accompany the order DUNCAN BROS., Manuf'rs. 131 & 133 S. CLARK St. Chicago. r^ ^ir 7&. ■^W- ^¥^ NATIONAL LIBRARY OF MEDICINE NLM DDTbO^a 1 NLM009604631