The Eye as a Factor in the 
Causation of sonmCommon 
Nervous Symptoms, with 
Hints respecting the 
Examination of that 
Organ. 
BY 
AMBROSE L. RANNEY, M. D., 
PROFESSOR OF THE ANATOMY AND PHYSIOLOGY OF THE 
NERVOUS SYSTEM IN THE NEW YORK POST-GRADUATE 
MEDICAL SCHOOL AND HOSPITAL; PROFESSOR OF NERV- 
OUS AND MENTAL DISEASES IN THE MEDICAL 
DEPARTMENT OF THE UNIVERSITY OF VERMONT. 
REPRINTED PROM 
K\\e Neto Yorft journal 
for February 27, and March 13, 1886. Reprinted from the New York Medical Journal 
for February 27, and March 13, 1886. 
THE EYE AS A FACTOR IN THE CAUSA- 
TION OF SOME COMMON NERVOUS 
SYMPTOMS, 
WITH HINTS RESPECTING 
THE EXAMINATION OF THAT ORGAN.* 
By AMBROSE L. RANNEY, M. D., 
PROFESSOR OF THE ANATOMY AND PHYSIOLOGY OF THE NERVOUS SYSTEM IN 
THE NEW YORK POST-GRADUATE MEDICAL SCHOOL AND HOSPITAL ; PRO- 
FESSOR OF NERVOUS AND MENTAL DISEASES IN THE MEDICAL DEPARTMENT 
OF THE UNIVERSITY OF VERMONT. 
Although something has been written within the past 
few years in relation to the deleterious effects of errors of 
refraction and accommodation of vision and the condition 
known as “ muscular insufficiency ” upon the functions of 
the nervous system and the viscera,f the profession at large 
is not yet thoroughly awakened to the importance of the 
detection and correction of such errors. 
Most of you know that some persons can be made dizzy 
by looking from a height or inspecting a water-fall; you have 
doubtless seen laymen suffer pains in the head and be made 
“ sick at the stomach ” by trying on a pair of spectacles 
* An abstract of two lectures delivered before the students of the 
New York Post-Graduate Medical School and Hospital. 
f Priority in this field (save in respect to ocular defect as a cause of 
headache, which has been recognized in a somewhat imperfect way for 2 
THE EYE AS A FACTOR IN THE CAUSATION 
which gave relief to a friend.* You doubtless know that a 
“ squint ” in the eyes is very often due to some defect in 
the refraction of the eye or a weakness of its muscles ; hut 
possibly some of you do not know that a squint will occa- 
sionally disappear at once when the proper glasses are given 
to such a patient, without recourse to cutting the muscle. 
Perhaps it has never occurred to most of you that sight is 
the only special sense which we use constantly except during 
the hours of sleep. There is not a moment of the day or 
evening when we are not acquiring visual impressions of 
some kind. 
Fortunately for our nervous system, the normal eye takes 
pictures of surrounding objects without any muscular effort 
when the object is more than twenty feet away; hence, dur- 
ing the larger part of each day, the normal eye is passive, 
and is practically at rest, although performing its functions. 
How different is the condition of the far-sighted or “ hyper- 
many years) is justly claimed, as far as I know, by Dr. George T. Stevens 
of this city. Although his views have been regarded by some as ex- 
treme and untenable, those who have carefully and accurately investi- 
gated the eyes of nervous subjects can not, I think, deny that defects 
in refraction and accommodation, and insufficiency of the ocular mus- 
cles, are very important and generally neglected factors of causation. 
Authors can not afford to-day to utterly discard all mention of the tests 
for muscular insufficiency from neurological works, as they have done 
in the past. In point of fact, even the tests for errors in refraction are 
not described in the standard works on nervous maladies. Most authors 
seem to have been content with showing a cut of some ophthalmoscope 
and dismissing the subject with a few lines. It is safe to infer that 
such writers are either not familiar with the field here discussed, or not 
in the habit of employing the tests herein described upon their patients. 
I am sure (if this is not the case) they could not remain so apathetic 
and apparently indifferent to the results obtained. 
* Let a healthy child try on its grandfather’s spectacles and wear 
them for a time, and the effects of “ eye-strain ” will be very clearly ex- 
hibited by distressing symptoms in a few minutes. OF SOME COMMON NERVOUS SYMPTOMS. 
3 
opic ” eye, however, from the normal ! For this eye (since 
it is too short in its antero-posterior axis) all objects have to 
Fig. 1,—Diagram to illustrate Congenital or Acquired Defects in 
the Antero-posterior Diameter of the Eye.—The black line repre- 
sents the normal line of the eye. No. 1 represents the hyperopic eye ; 2, 
the myopic eye ; 3, the optic nerve. 
be focused by muscular effort, irrespective of their distance 
from the eye. Such an eye is never passive. It has no rest 
while the body is awake. It is always straining more or less 
intensely to bring properly upon the retina the images of 
objects seen. 
The Flattened Eye.—The “ hyperopic ” condition of 
the eye, or “far-sightedness,” as it is called, is a very common 
defect. It is especially frequent in persons of tubercular 
parentage.* It is well, therefore, to suspect the existence 
of this defect in children or adults whose ancestors have 
died of “ consumption.” 
Hyperopia can not be corrected too early in life. It is 
unquestionably one of the most frequent causes of “ sick- 
headachef which, as you know, runs in families. It is com- 
monly encountered also (among other optical defects) in 
subjects afflicted with chorea and epilepsy.f It is a con- 
* This is probably clue to the shallowness of the orbits, 
f I)r. George T. Stevens was the first, so far as I know, to advance 4 
THE EYE AS A FACTOR IN THE CAUSATION 
genital defect, and will never be “ outgrown,” as many peo- 
ple think. A hyperopic child, from the days of babyhood, 
suffers (unconscious perhaps of the fact) from a variety of 
symptoms which indicate the “ strain ” to which it is sub- 
jected in consequence of its efforts to see distinctly. Its 
eyes are liable to become easily suffused when it plays or 
looks steadily at near objects. A slight cast in the eye is 
sometimes developed. It occasionally “ sees double ” after 
it learns to read. It usually prefers and excels in out-of- 
door sports, which require only slight efforts at accommoda- 
tion of vision. It finds that study and close application to 
books bring an indescribable sense of weariness and dis- 
comfort ; hence, study becomes irksome and play brings a 
sense of peculiar relief. Some years ago Dr. Loring, of this 
city, wrote an article for “ Harper’s Monthly ” which treated 
of hyperopia and myopia in a charmingly lucid and popular 
manner. 
Now, one peculiar fact should be noticed here—viz., that 
hyperopic subjects often have remarkable acuteness of sight. 
They are very apt (when young adults) to boast of their 
power of vision. They can often read all the test-types 
made for distance (twenty feet or more) without an error. 
If the defect exists in a child, the parents will frequently tell 
the general proposition that ocular defect was an important factor in 
causing functional nervous diseases, that muscular insufficiency (chiefly 
of the externi) was particularly apt to cause such disturbances, and 
that they could be relieved by tenotomy. I have an epileptic child 
under my care at the present time whose attacks have averaged four 
a day for several years. The fits will cease at once when the child is 
at sea, possibly because efforts of accommodation are almost entirely 
dispensed with when on deck. Hyperopia, astigmatism, and external 
insufficiency exist in this patient. The use of atropine caused a com- 
plete cessation of the fits for several days. Why can not the eye act as 
a disturbing element as well as phimosis, sexual excesses, ovarian irri- 
tation, etc., concerning which so much has been written ? OF SOME COMMON NERVOUS SYMPTOMS. 
5 
you how the child can see things with distinctness which 
possibly they themselves can not see at all; how they have 
tested its eyes from time to time ; how absurd the idea 
seems to them and their friends that the vision of the child 
is defective ; and how unnecessary the use of glasses seems 
to them (even if the eye is abnormal) so long as the child 
can get along without them. In some cases no amount of 
explanation or pleading will persuade the parents to have 
the ophthalmoscope or atropine used upon the child’s eyes 
in order to decide the question of the existence of “ latent ” 
far-sightedness. 
Fig. 2.—Section or the Front Part of the Eye, showing the Mechanism of Accommo- 
dation. (Fick.) The left side of the figure (F) shows the lens adapted to vision at distances 
of over twenty feet; the right side of the figure (N) shows the lens adapted to the vision of 
near objects, the ciliary muscle being contracted and the suspensory ligament of the lens con- 
sequently relaxed. 
Some years ago I pleaded with a medical man to allow 
some oculist of reputation to examine his children’s eves, 
all of whom had weekly attacks of sick-lieadache, inherited 
from both the mother and father, and in whom a tubercular 
tendency was strongly marked. I was refused, and the 
statement was made that never, while the father lived, 
should a child of his wear glasses with his consent. One of 
these children wears to-day a convex glass with a twelve- 6 
THE EYE AS A FACTOR IN THE CAUSATION 
inch focus for distance; another wears the same glass with 
five degrees of prisms added. These only partially correct 
an insufficiency of the muscles which exists in addition to 
the hyperopia. A third child is highly hyperopic and astig- 
matic. In every one of these subjects immense relief has 
been afforded by the correction of an optical defect which 
had rendered their early life one of suffering. This is not 
an uncommon experience. I could cite many more, if I 
deemed it necessary to prove what is already accepted by oph- 
thalmologists as proved—viz., that hyperopia and eye-defect 
of other forms may prove to be fruitful sources of headache. 
There is a prejudice among laymen and some medical 
men that glasses are an injury when they can be avoided; 
because, as they say, “ a person becomes so dependent upon 
them when he once puts them on.” This argument should 
be exactly reversed, and construed as follows: Because na- 
ture becomes dependent upon a glass tvhich gives relief and 
corrects an existing strain upon the eye, no time should be lost 
in affording this relief 
Should a hip-splint be avoided (when the pain in the 
joint is arrested by it) because the patient feels his depend- 
ence upon the splint ? Should a child be allowed to go 
through life with a deformed eye simply because the defect 
is not apparent to himself or his friends on account of an 
unnaturally developed ciliary muscle (see Fig. 2), which for 
a time renders the eye capable of getting along tolerably 
well in spite of its deformity ? 
More harm is being done to-day to the community at 
large by this fallacious argument than it is possible to com- 
pute. Thousands of sufferers from sick-headache and neural- 
gia are to-day struggling along through life with an optical 
defect uncorrected, and, in many instances, after costly experi- 
mentation with drugs and doctors, are left in despair of cure. 
I speak strongly upon this point because I believe that OF SOME COMMON NERVOUS SYMPTOMS. 
7 
the gastric symptoms which accompany typical attacks of 
sick-headache are not to be explained (as they commonly 
are) on the ground that the “ liver is inactive,” or that “dys- 
pepsia exists,” or that “the gastric juice is weak,” or that 
“ the patient uses tobacco to excess,” or that “ he has been 
living too high.” Every one who has suffered for years 
with these attacks knows that they often occur without ex- 
plainable cause; that they are cured sometimes by eating, 
drinking, and smoking, and made worse at other times by 
similar indulgences or excesses; that every known remedy 
is apt, sooner or later, to prove inoperative, and that a sure 
specific for them is unknown among the drugs of our Phar- 
macopoeia. These subjects also know that life is rendered 
almost unendurable by the attacks at times. They are 
tractable patients, and will try anything, live in any way 
specified, and bear any privation without a murmur, if it will 
insure a cure. 
I believe, from a personal experience of my own of this 
kind (which it is unnecessary to relate here), and from 
some experience also in examining the eyes of this class of 
sufferers, that the symptoms of sick-headache are reflex in 
character to a large extent, and are due primarily in almost 
every case to some optical defect. We can easily demon- 
strate that disturbed brain-action from “ eye-strain ” may 
produce in a healthy child and in some adults all of the 
symptoms of these attacks in a few minutes. Why is it 
irrational, therefore, to affirm that a brain (disturbed by the 
constant efforts made to use eyes which are abnormal in 
respect to the refraction, accommodation, or the equilibrium 
which should exist between its various muscles) may mani- 
fest its disturbed state by nausea, headache, vomiting, dizzi- 
ness, constipation, and other evidences of imperfect per- 
formance of the functions of the viscera ? Does not our 
central nervous system regulate and directly control those 8 
THE EYE AS A FACTOR IN THE CAUSATION 
functions? Is it not as probable that the master when 
upset disturbs the servants under him, as to advance the 
argument that the servants themselves are the all-important 
factors in causation ? 
The Elongated Eye.—When the eye is too long 
from before backward, the patient is said to be “ myopic,” 
or near-sighted. Distant objects are more or less indistinct 
to such an eye in proportion to the excessive length of the 
antero-posterior axis of the eye over the normal standard. 
No amount of muscular effort can overcome or improve this 
defect in vision; hence these individuals are not subjected 
to the muscular strain which far-sighted persons constant- 
ly and unconsciously exert in order to see at a distance. 
Again, the near-sighted eye can read or perform any of the 
functions required of it (when brought sufficiently close to 
the object) without any muscular effort of an unnatural 
character. In contrast, the far-sighted eye has to exert a 
still greater muscular effort to see near objects distinctly 
than when employed upon distant objects; hence the fa- 
tigue, the blurring of letters upon a printed page, the 
watering of the eyes, the pain in the eyes and head, and 
the many other ills previously described. 
Near-sighted subjects are generally conscious of an eye- 
defect, because they can not see across a room with distinct- 
ness or recognize familiar faces on the street. They are 
apt to become very fond of occupations which bring the 
eye close to their work, because they have no difficulty in 
seeing the object. Near-sighted children are liable to be 
considered precocious beyond their years, because they 
prefer to read rather than to play out-of-doors. It is gen- 
erally safe to conclude that a child is near-sighted when it 
avoids out-of-door amusements in order to gratify a taste 
for reading or in-door occupations. 
Near-sightedness is less liable to induce nervous dis- OF SOME COMMON NERVOUS SYMPTOMS. 
9 
turbances than far-sightedness, provided it is not accom- 
panied by astigmatism or muscular insufficiency. Yet it 
should be remembered that myopic subjects are more fre- 
quently sent to the oculist for relief than hyperopic sub- 
jects are, because the defect in vision is very apparent to 
all in the former class, and is more often unsuspected than 
recognized in the latter. 
The Astigmatic Eye.—You may find, in the third place, 
when you have examined the eyes of patients or friends 
who suffer from headache, persistent neuralgic attacks, etc., 
that a condition of the eye known as “ astigmatism, ” may be 
detected, co-existing with far- or near-sightedness, or inde- 
pendent of these refractive errors. In such subjects the 
cornea or the lens of the eye (see Fig. 2) has a greater cur- 
vature in some meridians than in others ; hence the images 
of all objects seen are more or less distorted when they fall 
upon the retina. To this class of sufferers some letters in 
the tests employed will be distinct, while others will not. 
If a number of dots are made upon a blackboard or a sheet 
of paper, some will appear as ovals, with a hazy border, 
or as lines, while others will more closely resemble the 
normal appearance of the dots. Finally, if a card, with 
lines running from its center to its periphery (the “ clock- 
face test ”), is used, some of the lines will appear blacker 
than the rest and more clearly defined. Now, there can 
be no comfort to such subjects in their visual efforts. They 
learn by practice and experience to properly interpret, after 
a while, the imperfect images of objects seen, and they are 
aided in so doing by the fact that the outlines of letters, 
etc., become clearer in some positions, as regards the eyes, 
than in others; but, in spite of all that may be said to the 
contrary, the strain of using imperfect eyes tells upon most 
astigmatic persons sooner or later, and tends to excite reflex 
nervous phenomena of various kinds, To properly correct 10 
THE eye as a factor in tiie causation 
astigmatism by glasses is often an extremely difficult matter. 
It requires experience, a thorough knowledge of optics, and 
a familiarity with the practical use of the ophthalmoscope. 
There are comparatively few physicians (outside of the spe 
cialists in ophthalmology) who are capable of managing a 
bad case of this kind with perfect success. You can, how- 
ever, easily detect its existence in most cases. When you 
discover it, I would advise you to intrust its correction to 
skillful hands. 
Certain abbreviations are employed by oculists to desig- 
nate various forms of astigmatism which may be detected. 
These are of use in recording the results of an examina- 
tion : 
Ah stands for simple hyperopic astigmatism. 
Am stands for simple myopic astigmatism. 
H -(- Ah stands for compound hyperopic astigmatism. 
M -)- Am stands for compound myopic astigmatism. 
M -Ah, or H Am, stands for mixed astigmatism. 
The Asthenopic Eye.—Finally, it is very important 
that you determine (in each patient whose eyes are ex- 
amined by you) the condition of the muscles of the eye. The 
term “asthenopia” is commonly applied to that condition 
of the visual apparatus which entails suffering in con- 
sequence of a defective “ equilibrium ” * in the muscular 
power exerted upon that organ when a fixed position of the 
eye is maintained for any length of time. When a state of 
perfect equilibrium is impaired from a weakness in some 
muscle of the eye, the effects become manifested sooner or 
later by pain and great discomfort after the eyes are used 
for any length of time. I have seen patients who could not 
attend a place of amusement, or read or sew, for even a 
* A term brought into prominence by Dr. H. D. Noyes, of this city, 
in a paper read before the International Medical Congress at Copen- 
hagen on Insufficiency of the External Recti Muscles. OF SOME COMMON NERVOUS SYMPTOMS. 
11 
short time, without great distress from this cause. These 
patients may or may not have a refractive error. In some 
instances, no glass but prismatic ones will benefit them. 
A higli-couraged horse feels the will, as well as the sup- 
port, of his driver through the reins by means of the bit. 
Although his course and rate of speed are changed from 
time to time at the will of the driver, the reins are never 
slackened. The horse becomes acquainted with the desires 
of his master by a sense of increased or diminished tension 
upon the reins. He is guided to either side by a difference 
in the tension of the two, although the driver does not en- 
tirely relax his hold upon the opposing rein while he uses the 
guiding one, and the difference in tension may be very 
slight. 
So it is with the normal eye. It is both controlled and 
supported while performing its movements within the orbit 
by the eye-muscles (which are its reins). The brain is the 
driver. At its command the eye revolves, or remains sta- 
tionary at any desired point. The tension of muscles, op- 
posed to any movement of the eye required, is so modified 
by the brain as to insure the requisite support to the eye- 
ball, and to steady it as it moves. Thus a perfect equi- 
poise is constantly established between opposing forces, 
adjusted with the nicest care to meet the full requirements 
of the organ under all possible circumstances. The normal 
eye does not tremble or wabble when it moves or the at- 
tempt is made to hold it in any fixed attitude. It is a piece 
of machinery, perfect in all its parts, reliable in its move- 
ments, perfectly controlled by its master. 
The eye with “ muscular insufficiency ” is like a horse 
with an inexperienced and incompetent driver; the proper 
tension upon the reins is not maintained at all times, as it 
should be; there is no equilibrium between antagonistic 
muscles; fixed attitudes are maintained with difficulty for 12 
THE EYE AS A FACTOR IN THE CAUSATION 
any length of time; the brain becomes more or less dis- 
turbed by its inability to properly control the eye-move- 
ments, and exhausted by the continual strain imposed upon 
it by the efforts required to do so even imperfectly. 
Asthenopic subjects are very frequently encountered in 
the practice of a neurologist. The oculist, perhaps, sees 
them still oftener, because they are generally conscious that 
something is wrong with their eyes. Still, there are excep- 
tions to this rule. I have examined patients who showed, 
in response to appropriate tests, very high degrees of mus- 
cular “ insufficiency,” that came to me for the relief of symp- 
toms which had never been referred by themselves or their 
physician to any possible eye-defect. I recall the case of 
an epileptic who was placed under my charge. Ilis family 
assured me he had “ wonderful eyes ”; and they were sur- 
prised when I examined them with care. The results of 
this examination showed, however, that twenty-five degrees 
of external insufficiency existed (as measured by the vertical 
diplopia test), and that he was hyperopic and astigmatic to 
a marked degree. 
Insufficiency of ocular muscles seems to me to be a con- 
genital defect in most cases—possibly in all. It is encoun- 
tered in very young subjects. It is not a paralysis or a 
true paresis. It seems to vary with the nervous condition 
of the patient. It is not uncommon to note wide variations 
in the same case, if examinations are made from time to 
time. Possibly this fact helps to explain why competent 
observers do not always estimate the degree of insufficiency 
in a given case alike, even when similar tests are employed 
and equal care is given to the case. We have no way, as 
yet, of determining “ latent'' insufficiency, as we do latent 
hyperopia by atropine. Should a patient show us an in- 
sufficiency counteracted by a prism of a certain angle to- 
day, it only proves that he has at least that amount, not OF SOME COMMON NERVOUS SYMPTOMS 
13 
that he has no more. This statement can, I think, be 
demonstrated. It is an important fact to remember, when 
the results of examinations of such patients made by your- 
self are at variance with the observations made by another. 
Without further preparatory remarks, I pass to the con- 
sideration of the steps commonly taken to determine if the 
eye (regarded purely as a piece of mechanism) is perfect 
or imperfect. The study of the eye, when any of its com- 
ponent parts become the seat of disease, has no bearing upon 
the subject under discussion. This field is properly rele- 
gated to oculists. 
The Tests of Vision and Ocular Movements. 
The steps which should be employed in examining the 
eye for errors in refraction and accommodation, as well as 
those employed to detect defect in the power of ocular 
muscles, have not thus far been discussed. I expect to 
offer nothing new, but I hope to make the details of such 
an examination simple and within the comprehension of all. 
The importance of this department of diagnosis can 
hardly be overestimated in nervous maladies. It has been 
my custom for some time past to examine the vision of 
nearly every patient sent to me, as my experience has 
shown me many times that remarkable cures may be made 
by the light thus shed upon the causation of obscure nerv- 
ous symptoms. 
Unfortunately for the sick, in many instances, physi- 
cians in general seem to think that the examination of the 
eye is too difficult a field for them to intrude upon without 
some special preparation for it. While this is undoubtedly 
true, in case the ophthalmoscope is to be employed, it is 
by no means a difficult matter for a person acquainted with 
physics to acquire a practical and satisfactory knowledge of 
the few tests here described in a comparatively short time 14 
THE EYE AS A FACTOR IN THE CAUSATION 
and with but a limited number of patients, provided that he 
works faithfully and intelligently. The healthy (?) as well 
as the sick can often be used to familiarize the beginner 
with the practical adjustment of prismatic, spherical, and 
cylindrical glasses, and also with the tests employed to 
detect “ asthenopia ” or insufficiency of the eye-muscles. 
Defective vision does not always produce ill-health; 
hence among your friends or in your immediate family you 
may find a field for investigation and practice. 
Now, in the first place, it is not necessary to have a 
complete Nachet case of lenses. Such a case is very expen- 
sive. By selecting a limited assortment of lenses and 
prisms, different combinations can be made to meet the 
needs of almost every eye-defect encountered in medical 
practice. 
Now, there is furnished, with the various small cases 
designed by prominent oculists, a sheet of Snellen’s test- 
types for distance, and also one containing several para- 
graphs printed in an assortment of types of various sizes, to 
te used as a test for reading power. Each paragraph is 
numbered, so that a record can be kept of the one read by 
the patient as a test. These test-type slips can he purchased 
separately, however, of any optician. It is best to have 
each mounted on card-board ; and it is well to have the one 
used in testing for distance a double one, with different 
letters on the opposed sides. If you suspect that the pa- 
tient is using his memory during the tests employed rather 
than his sight, the board can then be exposed upon differ- 
ent sides at various periods of the examination. 
You will find that the letters are mathematically made 
for testing distant vision. Above each line a numeral or 
Roman character is placed to designate the number of feet 
at which the normal eye should read the line with ease. 
Thus, the large letter on the top line will be designated OF SOME COMMMON NERVOUS SYMPTOMS. 
15 
usually by 200, or C C, while small letters of the lower line 
will be marked 10, or X. This shows that the top let- 
ters should be read easily at two hundred feet by the nor- 
mal eye, and the lower line at ten feet. After you have 
provided yourself with a good trial-case, a set of prisms, 
and the necessary test-type, let us see how you should pro- 
ceed with an examination of a patient’s vision. Let us 
illustrate the steps by using one of the class as a patient. 
I first hang up on the wall, as you see, the test type for 
distance; and I place the patient with his eye on the same 
level and a distance from it of exactly twenty feet. I then 
take the triple-grooved spectacle-frame from the trial-case and 
insert a plate of metal in the left rim of the frame, so that 
when it is used by the patient the left eye will be covered. 
I then place this frame upon the patient and ask him to 
read aloud the letters on the testing sheet from the top 
downward, line by line. This act tests his vision in the 
right eye. I note (while he reads) the following facts: (1) 
If he calls all the letters properly ; (2) if he reads without 
apparent effort; (3) at what line he fails to read. I then 
make a record as follows: 0. D. (oculus dexter, or right 
eye) V. = — The dash in the fraction is filled 
— (type) 
with the number which indicates the last line which the 
patient reads. When the vision is normal, the fraction 
20 20 
will be as follows: Y. = — or —. If the patient fails at 
20 xx 1 
the line next above the normal point, the fraction would be 
. , 20 20 , 
expressed by — or —. Kemember that the numerator 
F ; 30 xxx 
represents the distance (in feet) between the patient and 
the test-type, and that the denominator represents the 
numeral on the test-card placed above the last line of type 
read by the patient (which indicates the normal distance in 16 
THE EYE AS A FACTOR IN THE CAUSATION 
feet at which it should be legible to the normal eye). Now, 
if the vision of the right eye is found to be defective, try 
and improve it, and, if possible, to render it normal, or as 
nearly so as possible, by testing the effects of concave or 
convex glasses upon it as the case seems to indicate, begin- 
ning with the weakest lenses and gradually increasing their 
strength until the vision reaches its highest acuteness. This 
takes some little practice and experience. If convex glasses 
are found to be indicated, note the strongest which gives the 
best vision to the patient; if concave, record the weakest 
glass that overcomes the defect. 
In some cases you may find yourself unable to obtain 
normal vision in either eye by means of cylindrical or spheri- 
cal glasses. I presuppose a certain degree of acquired facil- 
ity on your part with glasses of the forms specified, and a 
carefully made effort to overcome the existing defect. 
In such a case it is well to consult some expert oculist 
(if near at hand), and thus to ascertain the results of an 
ophthalmoscopic examination. The patient may have some 
mechanical impediment to vision, such as an opaque lens 
within the eye (cataract), or an opacity of the cornea; or he 
may have a high degree of astigmatism, which can often be 
estimated with some accuracy by the ophthalmoscope. 
Again, he may be found to be suffering from morbid 
changes within the optic nerve or the retina. 
When it is found that a patient is so blind in an eye as 
to be unable to recognize any of the letters on the testing- 
card at any distance, you should note (before sending him 
to an oculist) if he can recognize with accuracy the number 
of fingers which you hold before the eye, and record the 
results of such investigation. You should make this test 
with the fingers in all possible positions in reference to the 
diseased eye (directly in front, above, below, and to either 
side of it). OF SOME COMMON NERVOUS SYMPTOMS. 
17 
We might record the results of an examination of a sup- 
posititious case up to this point as follows: 
O.D. Y. = (manifest) made — by -f- 30 glass. 
XXX XX 
The word “ manifest ” in this record means that the far- 
sightedness or “ hyperopia,” which apparently exists, is 
overcome by a convex or (-j-) glass which focuses at thirty 
inches. After the use of atropine, any increase over this 
amount which may be developed is recorded as “ latent " 
far-sightedness. I use here the old style of numbering 
glasses for the sake of perspicuity, although I personally 
prefer the metric system (dioptre), as it allows of more rapid 
combinations when the trial-case contains only a limited 
supply of lenses. 
You will understand, when I exhibit the method of re- 
cording such observations more fully to you, why it is that 
the right and left eyes have to be separately examined and 
corrected (as already described) before the binocular vision 
is tested with and without the needed correction. I usually 
make upon the page of my own case-book a note prior to 
the use of atropine somewhat as follows: 
20 20 
0. D. (right eye) V. = — (manifest) made — by -j- 30, 
0. S. (left eye) V. = ~ made — by — 30, 
TT 20 . 20 , ,, . 
Binocular V. = made — by this combination. 
XXX XX 
Such a record of a supposititious case would show that 
the patient was far-sighted or “ hyperopic ” in the right eye, 
and near-sighted or u myopic" in the left eye. It would 
lead me to believe also that the right eye (when under the 
influence of atropine) might show a still greater defect, 
which is now rendered “latent,” or hidden, by an excessive 
development of the muscle of accommodation. 18 
TIIE EYE AS A FACTOR IN THE CAUSATION 
In all far-sighted eyes Nature tries from the date of 
birth to compensate for the congenital defect (an eye which 
is too flat) by a hypertrophy or enlargement of the ciliary 
muscle (see Fig. 2); hence, when this muscle is temporarily 
paralyzed by atropine, the true refractive condition of the 
eye is no longer masked. Far-sighted patients, therefore, 
lose their clearness of vision more or less at once when 
atropine is used. The normal or the “myopic” eye, on the 
contrary, is but little affected (as regards the outline of ob- 
jects seen at twenty or more feet from the eye) by the use 
of atropine, although excessive light may annoy the eye in 
any case. 
Let us now suppose that during the examination of a 
patient we first have examined each eye separately, care- 
fully corrected all existing error found, and succeeded in 
getting or normal vision, for each eye separately; that 
we have then tried both eyes together with the glasses best 
adapted for each, and found the patient able to read the 
normal type for distance without fatigue or conscious ef- 
fort ; and, finally, that we have made a careful record of 
each point noted during our observations. Are we now 
prepared to order glasses for the patient ? Have we noted 
all that is important to note? To both of these inquiries I 
would say to the beginner, emphatically, “No.” Several 
steps still remain to be taken, even before the use of atro- 
pine (which it is generally best to employ before a final 
decision is arrived at). 
This brings us to the tests for muscular insufficiency. 
Until within a comparatively few years the necessity of 
carefully measuring the power of adduction and of abduc- 
tion of the eyes, and of determining the presence or absence 
of muscular insufficiency in “nervous” subjects, seems to 
have been practically disregarded even by oculists. Even OF SOME COMMON NERVOUS SYMPTOMS. 
19 
to-day this defect (which probably is, as a rule, congenital) 
seems to be omitted from prominent mention among the 
enumerated list of a3tiological factors of nervous symptoms 
by almost all authors of note. In some cases I have 
known it to be overlooked even by ophthalmologists of 
world-wide reputation, simply on account of a careless and 
hasty examination for the defect. It is an extremely com- 
mon defect of the eye ; and may prove a very serious one 
to the patient. It is an important factor in many subjects 
afflicted with headache; it often exists to a high degree in 
epileptics; it is frequently found among children who suffer 
from chorea; it may unfit a patient for sewing, reading, at- 
tending places of amusement, or using the eyes in any 
way for any length of time. I have known it to cause 
vomiting and so-called periodical “ bilious attacks ” by ex- 
citing a reflex irritability of the central nervous system. 
One patient of mine (a close student) was completely cured 
of chronic dyspepsia by the use of prisms which corrected 
an insufficiency of 6° of the external recti muscles; he now 
uses his eyes without fatigue, and all bodily ailments have 
disappeared without the use of drugs. 
In order to properly determine the condition of the 
ocular muscles, several tests have to be made. I do not 
personally regard any of these alone as sufficient for diag- 
nostic purposes. The tests which I advise you to invariably 
employ are as follows: 
1. Direct the patient (as you see me do with a member 
of the class) to look fixedly with both eyes at some small 
object (say the point of a pencil), and to follow it as I move 
it before the face of the patient at a distance of about ten 
inches. I watch both eyes carefully at the same time and 
note if a tremulous movement in either eye is present in any 
position of the eye as it moves about, and if the two eyes 
act in perfect unison with each other. 20 
THE eye as a factor in the causation 
2. While the patient is instructed to fixedly gaze at the 
same object, I next shield one eye with a card or sheet of 
paper so as to exclude the object from view, while I observe 
at the same time any deflection or trembling of the covered 
eye. If deflection or trembling occurs, it indicates a weak 
muscle. 
3. I next place upon the patient a spectacle-frame pre- 
viously arranged with a disc of ordinary glass tinted red 
to cover one eye, and a prism of 5°, with its base directed 
vertically downward, before the other eye. I then direct 
the patient’s vision upon a candle-flame at a distance of 
twenty feet. The prism causes two candles to appear (one 
being colored red by the glass of that hue), both of which 
to the normal eye should be seen in a vertical line. If the 
red image is seen to the side of a vertical line dropped 
through the white image corresponding to the eye with the 
red glass, the external recti are insufficient; if the red image 
is seen on the opposed side of the vertical line, the internal 
recti muscles are weak. 
4. Any deviation of the candle which exists can be 
remedied easily by placing a prism with its base outward 
before one eye for external insufficiency, and with its base 
inward for internal insufficiency. The strongest correcting 
prism that can be worn without an over-correction marks 
the degree of the “ manifest ” insufficiency only; hence we 
will note variations from time to time. I usually note both 
the weakest and the strongest prism which corrects the 
candle-deflection. 
5. I next test and measure the power of adduction and 
abduction (convergence and divergence) of the eyes by 
means of prisms. To do this I set a lighted candle twenty 
feet from the patient on a level with his vision when seated. 
I then hold before one eye a prism, with its base directed out- 
ward, of sufficient angle to cause two images of the candle OF SOME COMMON NERVOUS SYMPTOMS. 
21 
to appear when both eyes look at the object. I then in- 
struct the patient to make an endeavor to draw the images 
together and to fuse the two into one image. This is the 
test for adduction or convergence. The normal eye should 
overcome a prism of at least 23° to 25°. It may overcome 
60° in some instances. In the same way a prism with its 
base directed inward is used to test the 'power of abduction 
or divergence. The external recti muscles should not fail 
to overcome a prism of at least 8°. By combining prisms 
of varying angles, one of the requisite angle can be easily 
obtained with but a few prisms in your trial-case. The 
power of abduction and adduction should always be re- 
corded when accurately determined. One fact should be 
stated, however, in this connection—viz., that several sit- 
tings are usually required before the patient learns to use 
his eye-muscles to the best advantage; hence the records of 
daily tests should be kept for purposes of comparison for a 
short time (when practicable to do so). 
6. The power of convergence and divergence of the eyes 
can be estimated for near objects by means of a stereoscope 
modified by Professor Henry D. Noyes, into which prisms 
may be dropped at will. I have used it of late with some 
satisfaction, but I find that the accommodation seems to 
modify the power of ocular muscles (as determined by the 
previous test at twenty feet distance). Prisms vary accord- 
ing to the glass used in their construction. 
7. Following an example previously set by a late author, 
I record the results of the test (described as the third one) 
under the contraction for vertical diplopia—viz., v. d. 
8. It is well to exercise the muscles of the eye with 
prisms before the results of the vertical diplopia test are 
finally recorded. I have found that, after a flexibility of 
the eye muscles has been obtained by the aid of prisms, an 
insufficiency of the internal or external rectus muscle will 22 
TIIE EYE AS A FACTOR IN TIIE CAUSATION 
sometimes manifest itself where it was not apparent at first. 
That this is not simply the result of fatigue seems proved 
by the fact that the insufficiency remains more or less appa- 
rent during subsequent examinations. 
Thus far, then, in the examination, our record-page in 
blank would stand as follows: 
Name Residence Date 
O. D. V. = “ corrected by .... glass. 
0. _ » u u _ _ _ u 
Binocular V. =2® “ “ .... “ 
V. D. .. insufficiency... “ “ ....prism. 
Adduction, 20 feet, prism.. . 10 inches, prism. .. °. 
Adduction, 20 feet, prism.. . ®; 10 inches, prism.. . °. 
Reading power at inches, corrected by 
glasses. 
Astigmatism .... corrected by 
Visual field 
All the data indicated for record in this table, except- 
ing the estimation of the degree of astigmatism and the 
outline of the visual field, have been referred to, and the 
tests for each have been given with some detail. 
The estimation and correction of astigmatism is a difficult 
matter for a novice, and sometimes for an expert. It will 
be better understood by reference to and close study of 
the standard text-books on ophthalmology. Moreover, the 
ophthalmoscope is often required to properly estimate the 
degree and kind of astigmatism which exists. I would say, 
in passing, that a high degree of astigmatism should never be 
disregarded or left xincorrected, especially if present in 
connection with abnormal nervous phenomena. It is a 
very common cause of headache and asthenopic symptoms. 
In estimating the visual field, an instrument specially 
designed for that purpose (the perimeter) greatly simplifies 
the step, and gives us at the same time an accurate repre- OF SOME COMMON NERVOUS SYMPTOMS. 
23 
sentation of its outline for subsequent reference. A draw- 
ing can be roughly made, however, of the visual field of any 
patient, by means of a blackboard and a piece of chalk, 
through a simple method described in most of the text- 
books. In some nervous cases it is very desirable that a 
register of the visual field be taken from time to time and 
preserved for reference. 
Now, when we have carefully examined our patient re- 
specting all the data indicated in the preceding table, are 
we safe in passing an opinion respecting the condition of 
the eyes? I would again say “No.” 
We have now reached a point where we should adminis- 
ter atropine to the patient. I usually employ a solution of 
gr. iv of sulphate of atropine to an ounce of distilled water. 
This can be kept constantly in your office in a phial with a 
rubber-top dropper substituted in place of a cork. A drop 
or two in each eye will suffice in most subjects to dilate the 
pupil widely and to paralyze the power of accommodation 
of vision for near objects in about three hours. In occa- 
sional instances it becomes necessary to keep the patient 
under its influence for several days, but this is not the 
rule. 
It is Avell to caution the patient, after using this drug, 
that he may possibly suffer from the sunlight, and that 
colored glasses will relieve‘him of this annoyance. It is 
also best to tell him that his vision may become very 
blurred for distant objects in case he is far-sighted; and 
that, in any case, he will be unable to read or to write by the 
aid of vision without glasses for several days. I have 
known hyperopic patients to become greatly alarmed at the 
rapid loss of vision which has followed the use of atropine; 
all of which could easily hav.e been avoided had they been 
prepared for it by timely words of explanation. It is 
always well to explain to far-sighted subjects the difference 24 
THE EYE AS A FACTOR IN THE CAUSATION 
between “ manifest” and “ latent” hyperopia, and to make 
them intelligent as regards the effect of atropine upon the 
“ focusing ” muscle before you administer it. If they are 
forced by their business to use their eyes for near-work 
while under the influence of atropine, a pair of cheap glasses 
may be given them for temporary use while under its in- 
fluence. 
I can not impress too strongly upon you the necessity 
of using atropine upon a patient (if young) for diagnostic 
purposes when an error of refraction or of accommodation 
is suspected. Personally, I do not regard an examination as 
complete without it. It solves the question of the presence 
of “latent” hyperopia—a very common defect and a very 
serious one (from the standpoint of the neurologist) if 
allowed to go unrecognized. It reveals the existence of a 
previous ciliary spasm. It often arrests headache as if by a 
magic touch, and solves the nervous origin of many other 
similar symptoms. 
Patients who boast of their acuteness of vision, and who 
apparently justify their statement by reading test-type at a 
distance without the aid of glasses, are often astonished and 
sometimes alarmed at the immediate loss of this power 
which is brought about by the use of atropine. This sur- 
prise is heightened when (by the use of proper lenses) their 
power of vision for distance is immediately restored, and 
they become conscious for the first time of the muscular 
effort which they have been compelled in the past to exert 
in order to see without them. I shall never forget, person- 
ally, the sensation which I experienced of “ seeing without 
effort ” when a latent hyperopia was discovered in my own 
eye, and corrected by glasses. 
These experiences are well-known facts among oculists, 
but to the profession at large they often occasion as much 
of a surprise as to the patient. OF SOME COMMON NERVOUS SYMPTOMS. 
25 
I could point to case after case in my own experience 
where the cause of neuralgic attacks, excruciating headache, 
vomiting, extreme nervousness, and many other symptoms 
(not apparently connected with eye-defect), would have re- 
mained unrecognized if atropine had not been employed. 
There is a rule given by most oculists—viz., to give to a hy- 
peropic patient the strongest convex glass * with which he 
can comfortably read the normal test-type (xx) at a distance 
of twenty feet. It is impossible in many cases to decide 
this fact without atropine or an ophthalmoscope. The 
former method is the best one, because the accommoda- 
tion of the oculist, as well as that of the patient, has to be 
excluded in the latter, and it has the advantage that it 
can be employed by the general practitioner as well as by 
the specialist. 
Now, after the patient returns to you with widely dilat- 
ed pupils, you should carefully repeat each step of the pre- 
vious examination. You should record the results of these 
tests and then compare them with those obtained before 
atropine was employed. If the eye is a normal one, the 
... 20 
vision will be — after atropine has been used, as it was on 
the first examination; but, when an error of refraction or 
accommodation exists, changes of a greater or less degree 
may be noted. You may find, moreover, that the power 
of adduction and of abduction of the eye will be modified 
iu some patients by the action of the drug upon the ac- 
commodation of vision, and that a different degree of mus- 
cular insufficiency may be detected. You can now decide 
* The advisability of a full-correction by glasses of existing hypero- 
pia can only be decided after the condition of the patient, his age, his 
susceptibility to reflex irritation from eye-strain, etc., have been care- 
fully considered. It is not usually advisable to force a young subject 
to wear a glass which fully corrects the latent hyperopia. 26 
TEE EYE AS A FACTOR IN TIIE CAUSATION 
intelligently as to the glass which is best adapted to restore 
vision for distant and near objects in each eye of the pa- 
tient, and you are prepared to advise the patient respecting 
the use of the glasses selected. Y ou can decide also respect- 
ing the question of the utility of prisms or of tenotomy if 
the patient has marked insufficiency of the muscles. You 
can judge more accurately respecting the proper angle of 
the prism required in case their use is indicated. I would 
caution you, however, against deciding this latter point be- 
fore the error of refraction (if such exists) is corrected, and 
not until the “vertical diplopia test” has been employed, 
after such lenses as are required to correct it have been 
placed before the patient’s eyes. I have seen patients who 
gave evidence of marked insufficiency (5° to 8°), when the 
refractive error was uncorrected, exhibit no such defect 
when glasses which corrected that error were worn. Prisms 
in such a case would inflict injury upon the patient rather 
than afford relief. 
In closing this lecture, I would remark that views which 
I have advanced respecting the dependence of abnormal 
nervous phenomena upon eye-defect are not new. They 
are in antagonism, however, to those of some authors, and 
have been more or less actively combated of late, especially 
in regard to eye-defect as a cause of chorea and epilepsy. 
I do not think the relationship between “ eye-strain ” and 
attacks of headache or neuralgia can be denied, although it 
is only hinted at by Anstie and is omitted by most authors 
who have written on the causes and cure of these distress- 
ing maladies. Some of our best neurologists, as well as 
most oculists, are now investigating with renewed interest 
not only the ametropic conditions of the eye, but also the 
eye with “insufficient” muscles. Facts are being daily 
substantiated beyond dispute which met with ridicule some 
years since. Every day, in my own experience, I am OF SOME COMMON NERVOUS SYMPTOMS. 
27 
strongly impressed with the curative effects of glasses in 
various forms of functional nervous disturbances. In my 
opinion, the neurologist of to-day who fails to familiarize 
himself thoroughly with the examination of the eye omits 
an evident line of duty both to himself and his patients. 
No neurologist can send all of his cases to an oculist for an 
opinion, and, even if he could do so, he should at least be 
able to verify the opinion thus gained respecting the refrac- 
tive errors found and the state of (he eye-muscles * lie re- 
quires a case of lenses and prisms in his office as much as 
an electrical outfit, and he should know how to use both— 
the one as an aid in diagnosis, and the other as a means of 
cure. Personally, I have come to regard the examination of 
any patient sent to me as incomplete until I have tested the 
state of refraction and accommodation, and examined with 
care the condition of the ocular muscles. This view lias 
not been hastily formed, and my daily experiences confirm 
me in it. I believe the time will come when the tests em- 
ployed in eye-examinations will rank in importance in neu- 
rology with the knee-jerk test, which for generations, as 
Gowers remarks, simply “ amused school-boys.” REASONS WHY 
Physicians should Siscrihe 
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