i. 
Purulent Otitis Media, caused by the Nasal Douche, and 
accompanied by Double Hearing. 
ii. 
The Influence of Spectacles on the Optical Constants 
and Visual Acuteness of the Eye. 
Large Cyst of tlie Iris, cured by Operation. 
ii 
IV. 
A case of Extirpation of a Cancroid Growth of the Inner 
Canthus and Upper Eyelid. Blepharoplasty by 
Sliding Flaps; 
By Prof. II. KNAPP, M.B., 
Surgeon in Chief to the JVeiv York Ophthalmic and Aural Institute. 
Reprinted from the Archives of Ophthalmology and Otology, I., 2, 1870. 
’■ JIew York : 
WILLIAM WOOD & COMPANY, 
61 Walk: k . i k"et. 
187c. PURULENT OTITIS MEDIA, CAUSED BY THE NASAL 
DOUCHE, AND ACCOMPANIED BY 
DOUBLE HEAIRNG. 
H. KNAPP. 
The use of Weber’s nasal douche for diseases of the 
naso-pharyngeal region has of late become very exten- 
sive. Some recent publications, however, show that it 
is not without serious danger. Dr. D. B. St. John Boosa 
describes in the first number of these Archives (p. 259, 
etc.) a case in which the origin of a purulent inflamma- 
tion of the middle ear, of the very severest kind, could 
be traced to the use of the nasal douche. He adds that 
he had observed other cases in which the nasal douche 
was followed by bad symptoms, and that it hardly ever 
could be tolerated for any length of time. S. Moos, in 
a note to the German translation of Roosa’s communica- 
tion, confirms these views by stating that he saw the 
fluid which had been injected into the nostril by Weber’s 
douche, flow out of the ears in two cases of perforation 
of the drum-head. Although the application of the 
douche is not hurtful in such cases, they prove that 2 
water thus introduced into the posterior nasal space may 
penetrate through the Eustachian tubes into the tym- 
panic cavity. Moos, too, saw a case in which an acute 
aural catarrh was brought about by the nasal douche. 
The practical importance of these observations induces 
me to communicate a case of a similar kind :— 
A merchant of New York, 32 years of age, was in the habit of in- 
jecting, by Weber’s douche, warm water into his nose for chronic 
catarrh. He once took cold water, and felt, immediately after the in- 
jection, considerable pain in both ears, disappearing, however, very 
soon. Since that time he used warm water for six months without 
any unpleasant symptoms. Then he employed cold water once again, 
and experienced instantly in his left ear a severe pain, which soon 
abated, but nevertheless continued dull and annoying for a fortnight. 
Then suddenly it increased very much, was combined with headache, 
throbbing in the ear, loss of appetite, and deafness. Three days later 
an abundant purulent discharge from the left ear set in. He came to 
my office presenting all the symptoms of a very severe otitis media, 
with perforation of the membrana tympani. He remained under my 
treatment from March 6th to April 11th. Three weeks after his first 
call a great improvement had been obtained, the discharge was stopped, 
and the perforation in the drum-head closed for four days. Then an 
exacerbation and a new perforation occurred. The discharge kept 
flowing for a fortnight, when again an improvement was obtained, and 
the patient left New York to complete his recovery under the care of 
his father, a physician in the neighborhood of Philadelphia. 
There is no doubt that the purulent inflammation of 
the middle ear was caused by the flowing of cold water 
into the tympanic cavity. Whether warm water some- 
times or usually passed into the drum during the use of 
Weber’s douche cannot be ascertained, since the patient 3 
never felt it. I am satisfied that water can penetrate 
into the drum only when the patient accidentally swallows 
during the time the current is running over the orifices 
of the Eustachian tubes. It is easily explainable that 
cold water is more apt to provoke involuntary swallow- 
ing than warm. Moreover, the latter, when passing into 
the tympanum, would probably not cause much reaction 
or bad consequences. It therefore is certainly less ob- 
jectionable than the use of cold water in cleansing the na- 
sal and upper pharyngeal region. Since the observation 
above related, and the communications of Poosa and 
Moos, I have not recommended any more the use of the na- 
sal douche, but applied injections of astringent remedies 
by the posterior nares syringe. They are disagreeable 
for a great many patients, producing very unpleasant fits 
of sneezing and coughing, but their action is efficient, 
and, as it seems, devoid of danger. If we inject only 
small quantities of fluid, which is mostly sufficient, there 
is commonly no unpleasant reaction. 
Besides its origin, the above case was very remarkable 
for a symptom not much noticed yet, viz., double hearing 
with loth ears. Troltsch and Politzer mention its occur- 
rence only with two lines; Moos records in his “ Klinik 
der Olirenkrankheiten,” p. 319, etc., what is known on it. 
There are three incomplete observations in older litera- 
ture, to which are added two of Moos himself, and one 
of Von Wittich. The first of Moos’ patients, suffering 
from acute aural catarrh, heard simultaneously the third 
of each tone he was singing. The catarrh and double 4 
hearing disappeared both together very soon. The 
second patient had impairment of hearing from chronic 
aural catarrh for ten years. One evening, to shorten a 
fit of his habitual asthma, he anaesthetized himself by 
chloroform. On awaking his deafness was very much 
worse, and he heard all the sounds of the upper three 
octaves of a piano double. During the course of some 
months his hearing power diminished still further, the 
double hearing continued for some time, and ultimately 
all musical sounds appeared to him so perverse that 
music in general, which he had been very fond of before, 
became a perfect horror to him. In none of these two 
cases mention is made which ear perceived rightly the 
natural tone, nor whether the pseudo-tone was higher or 
lower in pitch. The only well-analyzed case of the few 
cases of double hearing which are on record up to this 
day, is the observation made by Prof. Von Wittich on 
himself. The excellent physiologist of Koenigsberg no- 
ticed, four weeks after an acute purulent otitis media, 
that he heard all the tones of the middle octave of a jpiano 
half a note higher with the diseased ear than with the 
healthy one. His explanation is, that an exudation into 
the tympanic cavity, by altering the pressure of the 
fluid in the labyrinth, had changed the tuning of the 
terminal fibres of the auditory nerve. 
When I examined the patient whose history I have 
sketched above, three days after the discharge had set 
in, I found in the diseased ear the hearing power for 
noises very much diminished (a watch of 6' hearing 5 
distance was heard from £"), whilst musical sounds 
were nearly as sharply perceived as in the normal state. 
A large tuning-fork, placed on the glabella, was heard 
double, and in the affected ear more strongly and about 
tivo tones higher than in the sound ear. On trial with a 
piano I found out that the same anomaly existed for the 
tones of the middle and next higher octaves, but not 
for the deeper ones. It was not distinctly marked at 
which note of the musical scale the double hearing be- 
gan, nor where it terminated. This anomaly existed 
unchanged during the first week, as long as the perfora- 
tion of the membrana tympani was large and the dis- 
charge abundant. Then the double sounds gradually 
came nearer to each other in pitch, until, at the end of 
three weeks, they hardly differed by half a tone, and 
sometimes were heard separately only by strained 
attention. After the relapse the double hearing was 
again a little better perceived, but the two tones never 
differed so much as in the beginning; moreover, their 
difference in pitch was changing from day to day. I 
have not heard of the patient since he left New York. 
This observation has many features in common with 
that of Von Wittich, above all, the origin of the anomaly 
in an acute purulent otitis media. The principal dif- 
ferences of both cases are the following: 1st. The 
pseudo-tone (that of the diseased ear) was higher in 
Wittich’s, lower in mine, than the right tone. 2d. The 
difference of pitch between real and pseudo-tone was 
greater in my case than in Wittich’s. 3d. The differ- 6 
ence of pitch between both tones was changing in my 
case, but constant in that of Von Wittich. 
I shall try to account for these differences, together 
with giving an explanation of the whole anomaly. The 
latter is most appropriately termed diplacusis binauri- 
cularis, in analogy with a similar anomaly of the organ 
of sight, viz., diplopia binocularis. Helmholtz1 s theory 
is perfectly adapted to explain binauricular diplacusis. 
In conformity with this theory we may compare the 
cochlear portion of the inner ear with a stringed instru- 
ment. Corti’s arcs or fibres—the strings—are so tuned as 
to yield all the sounds of the musical scale. Both 
cochleae represent two instruments in perfect accord. If 
a sound is produced in the air, the vibrations of the latter 
will be transmitted through both membranae tympani 
and the chain of the ossicles to those strings of Corti’s 
organ which are tuned for this sound, and thus sympa- 
thetic vibrations are occasioned in Corti’s fibres, and con- 
veyed to the brain by the filaments of the auditory 
nerve connected with the vibrating fibres of Corti’s 
organ. The same external sound will excite in either 
cochlea corresponding (identical) acoustic nerve fibres 
by producing sympathetic vibrations in corresponding 
(identical) arcs of Corti’s organ. In analogy with simi- 
lar conditions of both retinae, those fibres of both cochleae 
may be called corresponding or identical, the simultane- 
ous and equivalent excitement of ivhich generates but one 
sensation of sound. This constitutes the anatomical and 
physiological foundation of single hearing with both 7 
ears, in a similar manner as we see single with both 
eyes. 
Now, suppose the strings of one instrument (Corti’s 
organ) are tighter drawn, then this instrument will be 
differently, that is, higher tuned, so that a string which 
formerly made f. i. 300 vibrations per second now makes 
350 per second. Say 300 vibrations per second cor- 
respond to the tone c, 350 to the tone e. If, now, the 
latter tone, e, is sounded at any musical instrument, it will 
excite sympathetic movements in all strings so tuned as 
to perform 350 vibrations per second. (I may disregard 
entirely the harmonics.) In the healthy ear this will 
be Corti’s fibre corresponding to the sound e, but in the 
diseased ear 350 vibrations are now performed by a fibre 
which formerly performed only 300 per second, and 
which, of course, is still connected with that auditory 
nerve-fibre Avhich always committed the impression of 
300 vibrations, that is, the tone c, to the brain. There- 
fore this ear will engender the perception of the lower 
sound c, whilst at the same time the other one will en- 
gender the perception of the higher sound e. Such were 
about the conditions in the case of double hearing 
observed by me. 
The opposite state must have been present in Von 
Wittich’s case. He heard with the diseased ear the tone 
higher than with the healthy one. Suppose he heard 
with the latter the sound c (300 vibrations per second), 
and with the diseased the sound d (say 325 vibrations 
per second), then Corti’s fibre, tuned in the healthy state 8 
to 325 vibrations, must have been so much relaxed that 
it now made only 300 per second. An external sound, c, 
of 300 vibrations per second, will induce sympathetic 
vibrations in that of Corti’s arc of either ear which is 
tuned to 300 vibrations. In the healthy ear the right 
sound o is perceived, but in the diseased ear the relaxed 
arc will continue to excite the auditory fibre which 
always conducted the impression of 325 vibrations per 
second, that is, of the sound d, to the brain. Von Wit- 
tich made a very ingenious experiment to confirm this 
theory. If two tuning-forks, differing in pitch by half a 
tone, were so put before the ears that the lower one was 
before the diseased, the higher before the healthy ear, 
only one sound was perceived. The tuning-fork which 
yielded a lower sound produced sympathetic undulations 
in the relaxed Corti’s arc which formerly was tuned half 
a tone higher, and now the nerve connected with it is 
excited with its corresponding nerve in the other cochlea. 
Thus it is evident that diplacusis binauricularis may 
be of two kinds, by false higher tuning, tightening, and 
by false lower tuning, relaxing, of Corti’s organ. In 
the latter the pseudo-tone will be higher, in the former it 
will be lower, than the right tone. 
Ihe greater the difference in pitch, the greater will be 
the degree of false tuning, either by increased tension or 
by relaxation of Cortis organ. This principle explains 
the second and third points of difference between my 
case and that of Von Wittich.. There was, at the begin- 
ning of my observation, a morbid action on the cochlea 9 
about four times as intense as in Yon Wittich’s case. 
This morbid action, however, was not constant during 
the course of my observation, but decreased in propor- 
tion with the decreasing intensity of the inflammation. 
It was scarcely yet perceptible when the discharge had 
stopped and the perforation of the drum-head was 
closed. In a case of Dr. Gumpert (see Moos, 1. c., p. 
319) the difference of pitch of both sounds varied 
between a third, fourth, and octave during one week, and 
then disappeared entirely. 
Of what nature the changes are which produce false 
tuning of Corti’s organ, I am not at all prepared to 
answer. Yon Wittich assumes that exudation into the 
tympanic cavity changes the pressure of the fluid in the 
labyrinth. In his case the membrana tympani seems to 
have been entire at the time when diplacusis was noticed, 
for he adds that neither filling of the auditory canal 
with water, nor inflation of the tympanum with air, pro- 
duced any alteration in the double hearing. In my case 
diplacusis of opposite kind existed, with perforation of 
the membrana tympani. Is the integrity of the mem- 
brana tympani essential in relaxing Corti’s organ ? Does 
its perforation produce tightening of it ? I am unable 
to answer these questions. The first of Moos’ cases, 
acute aural catarrh, seems to be analogous with Wittich’s 
observation. “The patient heard simultaneously the 
third of every tone.” If here, what is not stated, but 
seems to be understood, the third was the pseudo-tone, 
then there existed, like in Wittich’s observation, dipla- 10 
cusis by relaxation of Corti’s organ. The drum-head 
was not ruptured. 
The other observation of Moos, where diplacusis was 
occasioned by anaesthetizing with chloroform in a case of 
chronic aural catarrh, seems to be an example of idio- 
pathic false tuning of Corti’s organ, that is, not dependent 
on inflammatory changes in the middle ear. I think 
that, for the present, it is of greater importance to collect 
more facts relative to this anomaly than to seek for a 
theory. 
The symptom of double hearing, when further studied, 
may be not only of physiological significance, but assume 
practical importance. It may guide our prognosis and 
treatment, by demonstrating that in the respective cases 
the labyrinth is either primarily affected or participates 
in some other disease. I suppose also that diplacusis 
binauricularis will be more frequently noticed than has 
been the case hitherto, if our attention be directed to it. 
With regard to future investigations, I propose that our 
inquiries should try to solve the following questions :— 
1. How great is the difference of pitch between the 
two sounds ? 
2. Has the pseudo-tone the same intensity and clang- 
tint (timbre) as the right tone (that of the healthy 
ear) \ 
3. Are these differences constant or varying during the 
duration of the anomaly ? 
4. Is the pseudo-tone higher or lower than the right tone 
(diplacusis by relaxation or tension of Corti’s fibres) ? 11 
5. Is it possible to obtain single bearing by producing 
tones of different pitch before either ear ? The tuning- 
fork placed before the diseased ear ought to differ 
so much in pitch from the tuning-fork placed before 
the healthy ear as the pseudo-tone differs from the 
right tone, but the difference in pitch must be of opposite 
direction, f. i., if the pseudo-tone is half a tone higher 
than the right tone, then the tuning-fork placed before 
the diseased ear must be half a tone lower than that be- 
fore the healthy ear. If the pseudo-tone is lower than 
the right tone, then the tuning-fork before the diseased 
ear must be so much lower. 
6. At which heights of the musical scale does double 
hearing begin and terminate, that is, how great is the 
range of double hearing t 
7. Are the limits, on the musical scale, between single 
and double hearing distinct or fading away gradually f 
8. If the entire Corti’s organ of one ear be differently 
tuned from that of the other ear, compound tones and 
pure chords must appear dissonant in binauricular, but 
consonant in monauricular hearing, also when in the latter 
case the healthy ear is excluded from the act of hearing. 
But if only a part of Corti’s organ of one ear be differ- 
ently tuned from the corresponding part of the other 
ear, all compound tones and the purest chords must ap- 
pear dissonant in monauricular as well as in binauricular 
audition. All music must be a horrible dissonance, as 
in the one of Mood cases. The examination has to de- 
termine of what hind these dissonances in monauricular 12 
and binauricular audition are, which will he possible by 
analyzing the anomaly according to Helmholtz’s theory. 
9. What is the cause of diplacusis t Is the latter de- 
pendent on a primary lesion of the labyrinth, or conse- 
quent to morbid processes in the middle ear ? In what 
state is the membrana tympani ? Is there any change in 
intra-auricular pressure ? 
A complete investigation of this kind may, at first, be 
fraught with difficulties, and perhaps deemed result- 
less ; but let me remind the reader that diplopia, not long 
ago, was an abstruse subject too, which has now become 
most valuable with regard to diagnosis, prognosis, and 
treatment of a large group of eye-diseases. 13 
THE INFLUENCE OF SPECTACLES ON THE OPTICAL CON- 
STANTS AND VISUAL ACUTENESS OF THE EYE. 
H. KNAPP. 
(a.) influence of spectacles on the ordinary eye. 
Every oculist at the present day is fully convinced 
that an accurate determination of the acuteness of vision 
(S) is of the greatest importance in the practice of ophthal- 
mology. The older methods are now all given up in 
favor of ascertaining S by a rational system of test-types. 
In cases of anomalous refraction, S is found out by 
means of convex or concave glasses neutralizing the 
anomaly of refraction. That, in doing so, a certain de- 
gree of inaccuracy is introduced by disregarding the 
magnifying and diminishing influence of these glasses 
is evident, but the amount of this inaccuracy has not 
yet been calculated. Even Donders, in his very ex- 
haustive treatise on the Anomalies of Accommodation 
and Refraction, does not touch this question. He says 
(p. 152) that, without further determination, a com- 
parison of tiie visual axgles can only be made if the 14 
visual object can be accurately seen with or without 
auxiliary glasses. 
I purpose now to examine what influence on the visual 
acuteness these auxiliary glasses exert in ametropic eyes. 
It is known that ametropia is caused not by any nota- 
ble changes in the refracting media and their surfaces of 
separation, but by changes of position of the retina. 
Therefore we may assume that the optical constants of 
ametropic eyes are equal to those of emmetropic ones. 
I shall take as a basis for the calculation the values of 
listing's diagranmiatic eye given in most text-books, 
for instance, Helmholtz1 s Physiological Optics, p. Ill, and 
IJonders' Accom. and Refraction, p. 67. (In the latter 
there is a misprint: line 7 from the bottom of the page, 
anterior focal distance of the eye ought to be 14,858 
instead of 19,875.) 
To solve the problem in a general way, I shall calcu- 
late the optical constants of a compound dioptrical 
system, consisting of the normal (or diagrammatical) eye 
combined with the series of our common spectacle- 
glasses. This work has not yet been done, and may also 
prove useful in solving other questions relating to vision 
through lenses. 
In the calculations I shall avail myself of the conveni- 
ent formulas given in Helmholtz's “Physiologische Optih." 
The usual distance at which spectacles are worn before 
the eye is about half a Paris inch. We may, therefore, 
place the auxiliary lens 14,858 mm. in front of the first 
principal plane of the eye. It is sufficiently accurate for 15 
oui' present purpose to disregard the thickness of the 
glass lens, its two principal and focal points falling 
together and coinciding with the so-called optical centre. 
By placing the glass 14,858 mm. before the first princi- 
pal plane of the eye, the optical centre of the first system 
coincides with the first focal point of the second system, 
the anterior focal length of the latter being 14,858 mm. 
These suppositions made, we can proceed to determine 
the position of the cardinal points of the compound sys- 
tem. 
f and f denote the first and second focal lengths* of 
the first system, which, being equal, may indiscriminately 
be represented byf 
<Pi and $2 denote the first and second focal lengths of 
the second system, the eye ; 
And d the distance between the optical centre of the 
glass lens and the first principal plane of the eye. 
d — 14,858 = $!• 
We find al h, viz., the distance of the first focal point of 
the compound system in front of the optical centre of 
the auxiliary lens by Helmholtz’s formula 11 a (1. c., p. 
56). 
a, t, =- ft) V 
d — <px — f2 
d being equal to and d — <£i = o, we therefore obtain 
ai t\ — o, 
* For the sake of simplicity of expression, I mean, in conformity with modem 
German opticians, by focal length always principal focal length, thus distinguish- 
ing it sufficiently from conjugate focal length or distance. 16 
which signifies that the anterior focal point of the com- 
pound system coincides with the anterior focal point of the 
eye. This result is valid both for positive and negative 
glasses. 
Formula 11b, 
a r — ~ $2 
8T* - TjR 
determines the position of the second focal point of the 
compound system behind the second principal point of the 
eye. 
Let us illustrate the calculation by an example, say 
lenses No. 10, convex and concave, viz.: lenses with 
270,6995 mm. of positive and negative focal lengths. By 
substituting the proper values, the preceding formula 
results in 
(14,858 - 270,6995) 19,875 1Q *Q. ■ , 
a2*2= — -- = 18,784mm. lor 
- 270,6995 
+ 10", 
and 
(14,858 + 270,6995) 19,875 on r 
270,6995 
— 10". 
Both these values, being positive, indicate the situa- 
tion of the posterior focal point of the compound system 
behind the posterior principal point of the eye. 
I shall now proceed to determine the principal points 
of the compound system. 
Formula lid (Helmholtz, 1. c., p. 57) 17 
, *A 
'h ~ d - -/, 
determines the position of the first principal point of the 
compound system in front of the first principal point of 
the first system. 
As d — fa = o, and f = fi, we obtain 
lh — — d. 
The same result is arrived at whether the auxiliary 
lens be positive or negative, since fx and f2 will in either 
case have inverse signs, thus rendering the value of hx 
negative in both instances. 
The negative sign before d means that the first prin- 
cipal point of the compound system does not lie in front 
of, but behind the first principal point of the glass lens. 
As we made d = fa, it follows that the first principal 
point of the compound system coincides with the fii'st prin- 
cipal point of the eye. 
Formula 11# (ibidem, 1. c.), 
■, d <p 2 
2_d-fa-fi’ 
determines the position of the second principal point of 
the compound system behind the second principal point 
of the second system / f2 being assumed positive, that is a 
convex lens (+10) placed before the eye. 
As d — <px = o, we obtain 
d $2 _ 14,858x19,875 
ll2 = :=rI2 ~ - 270,700 
h2 = — 1,0909 mm. 
This result shows that by placing a convex lens No. 10 
25 18 
before the eye, the second principal point of the compound 
system falls 1,0909 mm. in front of the second principal 
point of the eye.—The distance between the two princi- 
pal points of the eye being 0,4160 mm., this quantity 
subtracted from 1,0909 shows the position of the 
second principal point of the compound system 0,6749 
mm. in front of the first principal point of the compound 
system. 
We have determined above the position of the second 
focal point of the compound system to be 18,784 mm. be- 
hind the second principal point of the eye. To find the 
second focal length, which is the distance between the 
second principal point and the second focal point of the 
compound system, we must add 1,0909 mm. to 18,7$4 
mm. Thus we obtain the second focal length of the 
compound system 
F2 = 19,875 mm., which is = <2>2, the second focal 
length of the eye. 
If we place a negative lens (—10") before the eye, the 
second principal point is likewise obtained by formula 
lie, with the difference only that f2 being negative in 
this case, renders the value of h2 positive, namely— 
d (po 
= a - $>, + f, = i.0909™™- 
This shows that with negative glasses of the same focal 
length the second principal point recedes by the same 
quantity as it advances with positive glasses. 
The second focal length of the compound system is, 19 
therefore, obtained for concave glasses by subtracting 
this quantity from the value above found for a2 r2, which 
expresses the distance between the second focal point of 
the compound system from the second principal point of 
the eye. Therefore, 
F2 = 20,966 - 1,0909. 
F2 = 19,875 mm. = $2. 
Thus we have found that the second focal length, F.z, of 
the compound system proves equal to the second focal 
length of the naked eye, whether for convex or for concave 
glasses. 
The position of the nodal points is now easily ascer- 
tained, as, in every system, the distance of the first nodal 
from the first focal point is equal to the second focal 
length. All these quantities of the compound system 
having been found identical with the corresponding quan- 
tities of the naked eye, the first nodal point of the com- 
pound system must also coincide with the first nodal point 
of the eye. 
The equality of the posterior focal length of the com- 
pound system with that of the eye, has been obtained 
only by numerical calculation of one example, and from 
it the position of the first nodal point has been deduced. 
As this may not be considered sufficient evidence, I shall 
demonstrate it in a general way. 
Formula 11<^, 
i - d fi 
‘“d-fc-tf 
determines the position of the first principal point by the 20 
distance (d) of tlie glass lens from tlie anterior principal 
point, moreover by the anterior focal length of 
the eye, and the focal length of the glass (b = f2). The 
position of the focal points of a compound dioptrical sys- 
tem may be determined independently from the principal 
points, by proceeding from the nodal points of the single 
systems in a similar way as by making use of the princi- 
pal points. If d! signifies the distance between the second 
nodal point of the first system and the first nodal point 
of the second system, <£>2 the second focal length of the 
second system, and b and f2 the anterior and posterior 
focal lengths of the first system, the formula is trans- 
formed into the following: 
f 
X — —il 
1 - d'-ft-fi 
in which Kj represents the situation of the anterior 
nodal point of the compound system in front of the an- 
terior nodal point of the first system, 
d' = <p2 and b = f2, we obtain 
Kj = — d' = <p2, that is, the anterior nodal point of the 
compound system lies behind the optical centre of the glass 
lens by a quantity equal to the posterior focal length of 
the eye, and, therefore, coincides with the first nodal 
point of the eye. Since the anterior focal point of the 
compound system likewise coincides with the anterior 
focal point of the eye, it follows that the posterior focal 
length of the compound system equals the posterior focal 
length of the eye. 21 
If, instead of a convex lens, we place a concave one 
before the eye, these results remain the same, for fx and f2, 
which now are negative, enter into the above formula 
with inverse signs, consequently the value and situation 
of Kj will not be influenced. 
The distance between the two nodal points being 
always, in every simple or compound system whatsoever, 
equal to the distance of the two principal points, the 
second nodal point of our compound system must assume 
the same position relative to the first nodal point, as the 
second principal point to the Jb'st principal point of the 
compound system. 
Since, lastly, the second focal length of the compound 
system is the distance between its second principal and 
second focal points, and is equal to the second focal length 
of the eye, it is evident that the second focal point of the 
compound system takes the same relative position to the 
second focal point of the eye, as the second principal and 
nodal points of the compound system to the second prin- 
cipal and nodal points of the eye. 
If we recapitulate the foregoing investigations, we 
notice the following remarkable result:— 
Spectacle-glasses, held half an inch before the eye, do 
not change the situation of its anterior cardinal points, 
nor its anterior and posterior focal lengths, hut the situa- 
tion of each of the posterior cardinal points is altered in 
such a manner that convex lenses make them advance, 
and concave glasses recede by the same quantity. 
Having arrived at this conclusion, our practical calcu- 22 
lations are very mucli simplified, and, indeed, reduced to 
tlie evaluation of the position of either the second prin- 
cipal or second nodal point. This indicates at the same 
time what change has taken place in the position of the 
posterior focal plane, that is, the retina, and, conse- 
quently, in the length of the ocular axis. 
After having, in this way, determined the optical con- 
stants of a compound dioptrical system, consisting of 
the human eye and spectacle-glasses, we may now pro- 
ceed to investigate what influence the latter have on visual 
acuteness. 
The sharpness of vision in the normal eye is dependent 
on the density of the percipient retinal elements. We may 
fairly assume that the number of these percipient retinal 
elements, and of the optic-nerve fibres connected with 
them, is the same in all normal eyes. If, nevertheless, we 
find variations of S in different eyes which we must con- 
sider as normal, these variations result certainly more from 
deficiencies in the optical part of the eye than from vary- 
ing numbers of percipient elements and optic nerve-fibres. 
In diseased eyes, where the optic nerve, retina, and cho- 
roid have suffered, .the sharpness of vision sinks in propor- 
tion to the destruction of percipient elements. According 
to general acceptance, S is measured by the smallest visual 
angle, that is, the deviation of two lines which connect 
the second nodal point of the eye with two adjoining per- 
cipient retinal elements. Hence it follows that the visual 
angle, and with it S, will change whenever the distance 
between the second nodal point and the retina changes, 23 
the latter itself undergoing no alteration of structure. 
Spectacles move, as we have seen, the second nodal 
point, and therefore change the visual angle; but only in 
a few instances, viz., in presbyopia, and if the effect of 
weak glasses is counterbalanced by accommodation, we 
have to deal with normal eyes. The eyes which require 
spectacles in order to see at distance clearly and with 
ease, that is, without any accommodative effort, are not 
normal, but either too long (myopia), or too short (hy- 
peropia). Since, however, as we have said at the begin- 
ning, the refractive parts of these eyes are normal, the 
shortening or elongation of the ocular axis can only result 
from advancement or retrocession of the posterior portion 
of the ocular membranes. The retina of such eyes may 
be, and mostly is, as normal as in the emmetropic eye, and 
therefore must contain the same number of percipient 
Fig. 1. f. 
elements and nerve-fibres. Tlie necessary consequence of 
this fact evidently is, tliat tlie absolute density of the 24 
retinal elements is greater in short (hyperopic), and less 
in long (myopic), than in emmetropic eyes. In hyperopic 
eyes, the retinal surface, with all its elementary parts, may 
be considered as contracted, in myopic eyes, as expanded. 
If, in Fig. 1, the three curved lines represent a hypero- 
pic, emmetropic, and myopic eye, the radii drawn from 
the anterior nodal point (kj), will embrace between them 
corresponding portions of the retina, with equal numbers 
of percipient elements. The same number of the latter 
which exists in the normal eye must be distributed over 
a smaller surface in the hyperopic eye, and over a larger 
surface in the myopic eye. 
Let us now see what influence spectacles exert on visual 
acuity. Fig. 2 will illustrate this very plainly. A B 
Fig. 2. 
is to represent the visual line, \ and the anterior 
and posterior nodal points, and e the intersection of the 
retina and the visual axis in the emmetropic eye. h and 
m are the points of intersection of the visual line and 25 
retina, k\ and J?£ the posterior nodal points in tlie 
hyperopic and myopic eyes, thus displaced by spectacles 
neutralizing the errors of refraction. 
If the same object be looked at by each of the three eyes, 
it will appear under the same visual angle. This state- 
ment is at variance with the current opinion, that convex 
glasses, by advancing the nodal point, render the visual 
angle larger, and concave glasses render it smaller by 
making the nodal point recede. This would be true if 
both nodal points coincided, or were displaced, by spec- 
tacles in the same direction. In the naked eye they lie 
indeed close together, and during accommodative efforts 
their movements are homonymous, so that they may, for 
ordinary purposes, be regarded as coinciding. But for 
eyes armed with spectacles we are no longer allowed to 
make this concession, as I have shown above. Let, in 
Fig. 2, A kx represent the principal line of direction 
(principal axial ray of authors) of an object, Ckx a 
secondary line of direction (secondary axial ray), then 
the former will continue its course undeviated, while 
the latter will pass through the vitreous body parallel 
to its anterior portion (going through the air), but be dis- 
placed in such a way that the second nodal point (k() 
lies in the naked eye very little behind the first 
further behind (k™) in an eye armed with concave 
glasses, and in front of the second nodal point of the un- 
armed eye in eyes wearing convex glasses If we 
consider (in Fig. 2) the different triangles which are 
formed by the primary and secondary lines of direction, 26 
and tlie connecting lines of tlieir crossing points in tlie 
retina, we see tliat all tliese triangles are similar to one 
another, and especially the angles at the visual angles, 
are equal. 
When tlie hyperopic eye is not armed with spectacles, 
its retina, hi, is situate in front of its posterior focal plane, 
egR, but its posterior nodal point, Jc%, lies in the normal 
place. The secondary visual line cuts off the portion hgh 
of the retina. But when the hyperopic eye is armed with 
convex spectacles, the secondary nodal point advances 
(J4 ), and the secondary axis cuts off, on the retina, a 
larger portion, hi, than it did before spectacles were added 
to the eye. The larger portion of retina must, of course, 
comprise a greater number of percipient elements. If 
we now admit that in Figs. 1 and 2 eg6 are two adjoin- 
ing percipient elements of the retina, being approximated 
to each other, in the hyperopic eye, to the position hgh, 
then we see that the addition of a convex glass causes, 
of the same object, a larger retinal image than the naked 
eye. If he/1 represents the extent of the smallest per- 
ceptible retinal image, say f. i. of No. xx. Snellen, seen 
at 20' distance, the addition of a convex glass, increasing 
the retinal image of the same object to the extent of hi, 
would enable the same eye to distinguish at 20' dis- 
tance smaller type than No. xx. Sn. Thus we find 
its visual acuteness greater than x“, or S > 1. It is, 
therefore, evident that by wearing convex glasses the 
optical power of the eye increases, even if we leave out 27 
of consideration tlie correction of tlie impurity of the 
retinal images. 
o • 
Suppose somebody is able to see at distance distinctly 
without and with convex glasses (facultative hyperopia, 
Bonders), then his eye, when unaided, would form the 
perfectly pure image luf, and, when armed with a con- 
vex glass, the image hi quite as distinctly, but larger, of 
the same object. Therefore the eye, when armed with 
convex glasses, would be able to read smaller type than 
Sn. xx. at 20' distance, that is, his visual acuteness would 
be greater than normal, according to our usual method 
of testing. 
Both nodal points advance in every eye by accommoda- 
tion. By A = d this advancement amounts to 0,4 to 0,5 
mm., causing an adequate aggrandizement of the retinal 
images equivalent to that produced by convex spec- 
tacles No. 24, as the table further below demonstrates. 
In this way we are able to compare the aggrandizement 
of the image caused by accommodation in the unarmed 
hyperopic eye, with the aggrandizement of the image 
caused by convex glasses in the hyperopic eye. To de- 
termine how much the magnifying effect of convex 
glasses exceeds that produced by accommodation, we 
take the former in the table further below, and deduct 
from it the aggrandizement produced by accommodation. 
If, f. i., a patient with hyperopia = wishes to see clearly 
at distance wdthout glasses, he must make an accommo- 
dative effort of A- But this is only the third part of 
A = b; the aggrandizement by accommodation, therefore, 28 
is only one-third of that produced by a convex glass 
No. 24, or equivalent to that of + 72. We shall, here- 
after, see that the magnifying effect of glasses weaker 
than No. 10 may fairly be neglected for practical pur- 
poses ; so much the more may we disregard the influence 
of accommodation on the size of the retinal images. 
Apart from that, it is the object of the present investiga- 
tion to evaluate the changes of size brought about by 
spectacles in the retinal images, making abstraction of 
the optical purity of the latter. In that way only we 
obtain a correct measure to compare the visual acuteness 
of armed ametropic eyes with that of the unarmed 
emmetropic eye; for spectacles re-establish the purity of 
the retinal images, and render accommodation equal to 
that of the emmetropic eye ; but in doing so they more- 
over exert some influence on the size of the retinal image, 
and it is the amount and consequences of this accessory 
factor we are endeavoring here to ascertain. The fore- 
going lines, however, solve the problem raised by Don- 
ders, and quoted at the beginning of this paper, that a 
comparison of the visual angles can only be made, if the 
visual object can be accurately seen with or without 
auxiliary glasses. Instead of visual angles we would now 
say the size of the retinal images. 
The conditions of myopic eyes are easier to analyze. 
The retina, mgm, Figs. 1 and 2, being distended, displays 
a less density of its percipient elements. The line mgm 
may be supposed, as I have shown, to contain no more 
percipient elements than eg6 or hgh in the emmetropic 29 
and hyperopic eyes. If, now, mgm (Fig. 2) is the small- 
est perceptible retinal image of an unaided myopic eye, 
the addition of a concave glass would reduce this image 
of the same object to the size of mn, by shifting the 
second nodal point from backward to h™. The di- 
mension mn being less than the distance of two adjoin- 
ing percipient elements, or less than the smallest per- 
ceptible retinal image, the addition of a concave glass 
has rendered visual acuteness less than normal. 
The amount of increase or diminution of visual 
acuteness brought about by spectacles is proportionate to 
the increase or diminution they produce in the retinal 
images. This amount may be estimated as follows: 
Calculation of the amount of increase of the reti- 
nal image, and, consequently, of visual acuteness by con- 
vex glasses. 
Let hf = i®i,Fig. 2, be the linear dimension of a smallest 
retinal image of an hyperopic eye, and hi — jS2, the retinal 
image of the same object in the same distance when looked 
at through a convex glass, then ft and 02 constitute cor- 
responding lines in two similar triangles, and are to each 
other as their distances from the corresponding nodal 
points. The quantity by which the second nodal point 
is shifted on the axes may be called 8 = h\ \\ — h\ 1%, 
then hk| = Fi — S, since the distance of the second nodal 
point of the compound system from the retina is equal to 
the first focal length of the eye, hk| = Ft. We there- 
fore obtain the following proportion:— 30 
— = from wliicli is deduced 
0i f i ~ o, 
a _ Fi 
~ Fj— <5' 
If we give [3t the standard value 1, we obtain 
F 
02 = as the amount of 02 with regard to 0t. 
hi— o 
Fi being 14,858 mm., and 5 = 1,0909 mm. (for + 10 as 
we saw above), we obtain 
02 — 1,0793, as the co-efficient of any retinal image, when 
+ 10 is xoorn half an inch before the eye. 
If we measure visual acuteness by the smallest percep- 
tible retinal image, and assume the hyperopic eye had 
S — 1, it will have S = 1,0793 when armed with + 10. 
Since the linear dimension of the retinal image is in 
simple inverse proportion to the distance of the object, 
that is, decreases as the object is removed, Sn. xx. must 
be 1,0793 x 20' = 21,580'removed from an eye armed 
with + 10 in order to produce the smallest perceptible 
retinal image. 
( B.) Calculation of the amount of diminution of the reti- 
nal image, and, consequently, the visual acuteness, by con- 
cave glasses. In the unaided myopic eye the second nodal 
point lies in the same place as in the emmetropic eye, 
Fig. 2. Since the retina is distended proportionately to 
its retrocession, the retinal elements contained in the line 
eg6 of the emmetropic eye are distributed over the longer 
line mgm of the myopic eye. The retrocession of the 
second nodal point from ~k\ to h™, resulting from the ad- 31 
dition of a concave glass before tlie eye, generates from 
the same object which in the unaided myopic eye produ- 
ced the image my”1, now the smaller image mn. The 
relation of magnitude of both these images is easy to as- 
certain. m k™ is equal to Jh\ — 14,858 mm., and k™ k\ — 8 
is the retrocession of the second nodal point, amounting 
for a glass of 10" of negative focal distance to 1,0909 mm. 
If mn = z3'2 and mgm = fi1} the similarity of the respec- 
tive triangles shows 
— = d~'—r = 0,9316, 
fit F, + S 
which expresses the co-efficient of the diminishing power 
of concave 10". 
A myopic eye, armed with—10", therefore, must be con- 
sidered to possess normal acuteness of vision, if it is able 
to read Sn. xx. at 0,9316 x 20' = 18,632'. 
I have disregarded, in the foregoing investigations, the 
appearance of dispersion circles, and was certainly justi- 
fied to do so, because I founded the visual acuteness on the 
density of the percipient retinal elements and the dimen- 
sions <A the retinal images, making abstraction of all imper- 
fections of the latter. If an unaided ametropic eye looks, 
with relaxed accommodation, at a distant object, the cen- 
tres of the dispersion circles from the end-points of the 
object will fall on the same retinal elements as in the 
emmetropic eye, as is illustrated in Fig. 2 ; f, ge, and gm 
are the same retinal elements, that is, they are separated 
from the central element of the fovea centralis (h, or e, 
or m) by an equal number of intermediate elements. If 32 
e g6 are two adjoining retinal elements, then luf and mgm 
are likewise adjoining. 
The addition of spectacles to the eye has the effect of 
shifting the second nodal point on the axis. Hence the 
images of all the object points, except the one situate in 
the axis, are displaced, namely, removed from the axis by 
convex glasses, approximated to it by concave glasses. 
Thus it is evident that convex glasses cause the image of 
an object to cover a greater number of percipient retinal 
elements than if the same object were seen without 
glasses, whilst the inverse obtains with concave glasses. 
I have shown already that it is erroneous to speak, as it 
is generally done, of an augmentation or diminution of 
the visual angle by spectacles, for the visual angle re- 
mains unchanged, if glasses are worn at the usual distance 
of half an inch from the eye. 
I have now, in a general way, solved the problem to 
show what influence spectacles have on the optical con- 
stants of the eye, on the size of the retinal images, and 
on the acuteness of vision. I have, moreover, illustrated 
it by an example, No. 10 convex and concave. 
To render these investigations useful for reference, I 
shall tabulate the results of calculation concerning the 
series of our test-glasses:— 33 
*—* » »—* oo 
MMMMfcOtOCOW^CnOSSOOOOJO 
tojt— top to))—* 
Number of glass in 
Paris inches. 
MOOS®Ol^WWbOI.Ot-Jl--‘HMOO 
J-5 tO to fcO 4** CO'cs'h-‘'•-*'►-■ ac'ox'co'o'os'co 
ooMOiti.w®o»]H»aio30MM 
to to C Cl W 00 Ki ® to ** Cl to M OO 
Displacement of 2d 
cardinal points in 
millimetres. 
CO to >—‘J—‘J—1 I—1 H‘H>1—1■ 1—11—‘ t—<; t—'Ml-‘1—l 
'rfa.'oo CO Ox 4*-'oo'u>'fcO>'t-‘'>—> i—‘ t—1 ©'©'© 
ocoojtoooMkoatoMWMO^^ko 
StMOaOOitKO^t'OOMK-CDQOOi 
(Xm^OiOOCOOiCChOhmOIOO 
Co-efficient of magni- 
fying effect of con- 
vex glass. 
O o o o o © ©p o o o 
oi os ci —t oo*00*oo'bo'bo'co'c©'co'c©'c© 
go m o w s o io #—i o o h u a s 
WtOOSMWUO^tOMOiOih-ffiffi 
SSQOOOOCOHi-aOOOMOOtOtO 
Co-efficient of dimin- 
ishing effect of con- 
cave glass. 
JOJfrJOjt* J—1 00 pi OxjS-JW U> tCJ.O MOO 
O to Ox so Ox 
SOOxtOOtOOOMOi^O^tOCOOsO 
S being 1, No. xx. Sn. 
should be read with 
convex glass in Paris 
feet. 
J—1 Jo po S Jjfo JSs Js> J-l JM J» J» CD Jo Jo 
© 00 H1- o'*o'4i-'o'ox'co'Voo'H-‘'oo'o5'c-‘ Ox 
N OUO 00 M 00 S W O >MO O to W to to 
S — 1, No. xx Sn. 
should be read with 
concave glass in 
Paris feet 
.Remarks on the foregoing Table. 
Tlie displacement of tlie second cardinal points, that 
is, the second principal, nodal, and focal points, expresses 
at the same time the elongation or shortening of the 
ocular axis in degrees of ametropia corresponding to the 
number of the spectacle-glasses enumerated in the first 
column. The length of the ocular axis, that is, the dis- 
tance between the apex of the cornea and the fovea 
centralis retinae, in the normal eye, is 22,23 mm., ac- 
cording to Listing'1 s diagram. We may, therefore, avail 
ourselves of this table to determine, with the ophthalmo- 
scope or functional testing, the situation of any part of the 
fundus oculi with regard to the position of the posterior 34 
focal plane. If, for instance, a tumor or a circumscribed 
exudation projects over tlie background of tlie eye, we 
have first to ascertain with which auxiliary glass, put 
behind the ophthalmoscope, we can see clearly, by relaxed 
accommodation and in the upright image, the background 
of the eye, and, secondly, with which other glass we can 
see the summit of the projection. The difference of both 
glasses will give the height of the elevation by referring 
to the first and second columns of our table. Since this 
evaluation is of importance in judging the existence and 
amount of any elevation or depression, as well as its aug- 
mentation or diminution during the course of the disease, 
I shall illustrate the manner of this ophthalmoscopic 
measurement by some examples. 
1. In an emmetropic eye, the fundus of which an em- 
metropic observer sees distinctly without any auxiliary 
glass put behind the ophthalmoscope, and an ametropic 
observer with his neutralizing glass, there is a circum- 
scribed exudation or tumor, the summit of which is dis- 
tinctly seen in the erect image with all the convex glasses 
up to number 8, whilst with stronger glasses it appears 
indistinct. Then No. 8, the strongest convex glass with 
which the summit of the tumor appears distinct, indicates 
an elevation of the tumor by 1,36 mm. over the back- 
ground of the eye, as is seen by the number of the second 
column of the above table corresponding to No. 8.* 
* I have described this method of estimating the relief of the background of 
the eye at the meeting of the Societe Universelle d’Ophthalmologie, Aug., 
1867, in Paris, and given a table relating to it in my book on “ Intraocular 35 
2. The fundus oculi is seen with + 24 distinctly, the 
summit of a tumor with + 4. The height of the tumor 
is calculated as follows: J ~ or nearly ~. No. 
5 in the first column of the above table indicates, as seen 
in the second column, an elevation of 2,18 mm. over 
the level of the retina. 
3. The fundus is seen distinctly with — 20; the sum- 
mit of a tumor with + 10. ~o + 20 — =63 gives, 
with reference to columns the first and second, 1,66 mm. 
as the height of the tumor. 
4. A hyperopic eye, the retina of which appears dis- 
tinct with + 6, suffers from chronic glaucoma. The 
area of the optic disc appears plain with +18. How 
deep is the excavation? ~ Answer: 1,2 mm. 
This method of estimating elevations and depressions is 
especially valuable in the early stages of new growths 
and excavations, when the differential diagnosis and our 
judgment with regard to the progressiveness of the 
morbid action are apt to be difficult. 
The third and fourth columns of the above table do not 
require much explanation. Each glass of the first column, 
Tumors,” p. 106. The numbers there were obtained by another way of calcu- 
lation, and differ slightly from those given in this paper, because I took as basis 
of the former calculation the results of my own measurements on the living 
eye, whilst for the calculation of the present table the values of Listing's dia- 
grammatic eye are taken as basis. I have here preferred Listing's values, 
although they are perhaps not so generally correct as those obtained on the 
living eye, because they are at the reach of everybody, and the difference between 
the two is unimportant. Dr. Mauthner also describes the measurement of the 
depth of the background of the eye in his Treatise on Ophthalmoscopy, Vienna, 
1868. He gives some examples, but no table to refer to. 36 
by displacing tbe second nodal point, produces a certain 
alteration of tlie size of tlie retinal images. This alter- 
ation is found by multiplying tlie linear dimensions of 
tlie retinal images with the corresponding numbers of 
the third and fourth columns. Therefore I have called 
them co-efficients of the magnifying or diminishing effect 
of spectacles. 
The fifth and sixth columns need not much explication 
either. Snellen’s test-types being so chosen that the size 
of the letters or the intervals between them produce, at 
the distance indicated by their numbers, the smallest per- 
ceptible retinal images, then by looking with spectacles, 
on account of their magnifying or diminishing power, 
the distances of the types from the eye must be 
changed, if the images are to remain the smallest 
possible for distinct perception. We find the requi- 
site distance for each number of Snellen’s test-types, and 
for each spectacle-glass, by multiplying the number of 
the type with the co-efficient of magnifying or diminish- 
ing power of the glass. This having been done for 
No. xx with the series of test-glasses, the fifth and sixth 
columns give a comprehensive statement of the influence 
of spectacles on the acuteness of vision. We see that 
spectacles weaker than number ten have but a slight 
influence on the distance in which the different types 
should be read, so that we may fairly neglect it. Stron- 
ger glasses than No. 10 have a notable influence on the 
distance in which the type ought to be read. This influ- 
ence, however, is not so great as might perhaps be an- 37 
ticipated, since of strongest convex glasses No. 2 requires 
only one and a half of the distance indicated by the 
number of type, No. 4 nearly 1 of it, etc., whilst con- 
cave glasses No. 2 require only f of the distance stated 
in the number of type, in order to let visual acuteness 
appear normal. 
I think it is not practical to change anything in our 
accustomed annotations of visual acuteness. But when 
it is of importance to judge exactly of the acuity of 
vision, we may refer to the above table which will in 
a moment give us the correction to be made in our anno- 
tations. Say, for instance, a myopic eye can read with 
number two Sn- xx at 15', then we would note it as 
follows: M|, S*|. A look at column the sixth of our 
table will show us immediately that S in this case is not f, 
but 1. The use of the table for reference appears to 
me so simple, that I think it unnecessary to give any 
further examples. 
(b.) ixfluehce of spectacles ox the aphakial eye. 
The optical system of the aphakial eye—which means 
an eye whose crystalline lens has been removed, or dis- 
located, or absorbed—is essentially different from that 
of the emmetropic eye. As clear vision in aphakial 
eyes can only be brought about by the help of strong 
convex glasses, I shall now proceed to investigate what 
influences such glasses exert on the optical system and 
visual acuteness of aphakial eyes. In noting, at the 
present day, the results of our cataract-operations, we do no longer content ourselves by tlie general expres- 
sions that good or useful vision was obtained, or even 
that sight was regained, but we test the acuteness of 
vision in quite as rigid a manner as we do in ordinary 
eyes. To know the alterations which spectacles produce 
in aphakial eyes, is, therefore, not merely of theoretical, 
but of practical interest. 
I shall determine the optical constants of armed apha- 
kial eyes in the same manner as I did those of armed 
emmetropic eyes. 
The optical constants of tlie unarmed aphakial eye 
which constitute the second system, are the following 
<pt, the first focal distance, is = 23,692 mm. 
$2. the second focal distance, = 31,692 nun. 
Both the principal points coincide, and are situate in 
the apex of the cornea. 
Both the nodal points coincide likewise, and are situ- 
ate in the centre of curvature of the anterior surface of 
the cornea, namely, 8 mm. behind its apex. 
These values are borrowed from Listing's diagramma- 
tic eye, in conformity with our former inquiries into the 
optical constants of armed emmetropic eyes. The first 
optical system is represented by the convex glass lens, 
the principal and nodal- points of which, here too, may 
be assumed with sufficient accuracy to coincide with its 
optical centre. We admit that the latter is placed 12 
mm. in front of the eye. This, therefore, is the mutual 
distance—called d—of the principal points of the first 
and second systems. 39 
(I f 
Helmholtzs formula 11 d, h, = 7 7? will serve 
’ d — <p!~ 1 
to calculate the position of the first principal point of the 
compound system in front of the first principal plane 
of the first single system. Applied to lens + 3, that is, 
of 81,21 mm. of positive focal distance, it will result in 
12 x 81 
Id = 12 - 23,692 - 81,21 = ~ 10’48a mnL’ 
which means that the first principal point of the com- 
pound system lies 10,485 mm. behind the glass. Since 
the latter is placed 12 mm. in front of the cornea, the 
first principal point of the compound system lies 1,515 
mm. in front of the cornea. 
Formula lie, h2 = —--g determines the position 
of the second principal point of the compound system be- 
hind the cornea. It results for lens + 3 in h2 = — 4,0917 
mm. The — sign signifies that h2 lies in front of the cor- 
nea, and, as follows from the position of hx, 2,5767 mm. 
before the first principal point of the compound system. 
The latter number denotes at the same time the distance 
between both the principal points, therefore also that 
between both the nodal points of the compound system. 
For lens + 3, therefore, IIt II2 = Kt K2 = 2,5767 mm. 
The position of the first focal point of the compound 
system in front of the optical centre of the glass lens is 
obtained by formula 11 <7, aj tx — For lens + 3 
d ~ cfr - f 
this is found by calculation =10,216 mm. If we add 12 40 
mm. as tlie distance of the glass from tlie cornea, we ob- 
tain the position of the first focal point of the compound 
system in front of the cornea, namely, 22,216 mm. Since, 
however, the first focal length is reckoned from the first 
principal point, we must deduct 1,515 mm. from that 
quantity, and we obtain the anterior focal length of the 
compound system F! = 20,701 mm. 
The position of the posterior focal point behind the 
second principal plane of the second system—in our case 
the anterior surface of the cornea—is determined by for- 
mula 11 b, a2 t2 = . By inserting the proper 
d — — i 
values, we find for lens + 3 a2 r2 = 23,599 mm. It is evi- 
dent that this number represents at the same time the 
length of the AXIS OF AX APIIAKIAL EYE which 
sees at distance best with + 3. As, however, the poste- 
rior focal length is measured, not from the cornea, but 
from the second principal point, we must add to this 
quantity 4,0917 mm., the distance in which the second 
principal point of the compound system is situate in front 
of the'cornea. Thus we obtain F2 = 27,691 mm. 
The positions of the two nodal points of the compound 
system are easily found out by the following considera- 
tions 1The distance between the second nodal and the 
posterior focal points is equal to the first focal length. 
Therefore F2 — Fx = H2 K2, that is, the distance between 
the second principal and second nodal points, which is also 
equal to H K1? the distance between the first principal and 
first nodal points. For lens + 3 fitly, or H2K2, is equal 41 
to 6,990 mm. Since tlie first principal point lies 1,515 mm. 
before the cornea, we must deduct tins quantity from 
6,990, to find the position of the first nodal point behind 
the cornea. We obtain 5,475 mm. The position of the 
second nodal point is found in a similar way by deducting 
from 6,990 mm. the distance of the second principal point 
from the cornea, which amounts to 4,092 mm. We ob- 
tain Iv2 lying 2,898 mm. behind the apex of the cornea. 
In this way all the optical constants of an aphakial eye 
armed with + 3 are determined. 
Let us now inquire what influence spectacle glasses 
exert on tlie visual acuteness of aphakial eyes. 
We assume that the eye, before it was deprived of its 
crystalline lens, possessed normal visual acuity. The posi- 
tion of its retina, that is, the length of its antero-posterior 
axis, can be determined, after its lens has been removed, 
by formula 11&, as we have seen. Since we know the opti- 
cal constants in the aphakial state, we can calculate the 
Fig. 3. 
size of the retinal image of any visual object. B, in Fig. 
3, may represent a small remote object which the apha- 42 
kial eye, armed with -f 3, is able to see distinctly. The 
one of its end-points may be situate on the optical axis 
of the eye. The line of direction of its other end-point 
is, in its course through the air, directed to the first nodal 
point K1? and passes, in its course within the vitreous 
body, through the second nodal point K2, while remain- 
ing parallel to its first section in the air. Thus the reti- 
nal image 02 is defined. If we now imagine the same eye 
to be still in possession of its normal crystalline lens, we 
may draw in it the retinal image of the same object seen 
in the same distance. Since cornea and lens are assumed 
to be normal, the optical constants of Listing's diagram- 
matic eye may be used for the determination of the reti- 
nal image. Fig. 4 may illustrate this. To find out the 
Fig. 4. 
magnifying effect of tlie glass lens, we liave to compare 
the sizes of the retinal images and formed, in both 
eyes, of the same object B. The triangles formed by the 
retinal images and their connecting lines with the poste- 
rior nodal points being similar to each other, the sizes of 
both images are to each other as their distances from the 43 
y-|-| 
second nodal points. — = — If we attribute to 
ft m x2 . 
m K 
z3! the value l,then /32 = 2. The quantity mK2 is 
m x2 
known, and equal to the anterior focal length F1 of the 
lensless eye when armed with + 3. The quantity niz2 
may be called <p, and determined as follows. We found 
the axis of this eye equal to 23,599 mm. The posterior 
nodal point is situate 7,373 mm. behind the cornea. <p, 
therefore, is equal to 23,599 — 7,373 = 16,326 mm. We 
obtain, consequently, = 1,2758. This is 
$ 16,326 
what we have called the co-efficient of the magnifying effect 
of the glass lens. The distance at which any number of 
Snellen’s test-types ought to be read by a lensless eye, 
when armed with + 3 and endowed with normal visual 
acuteness, is obtained by multiplying this co-efficient with 
the number of the type, for instance, No. xx should be 
read in 20 x 1,2758 = 25,52 feet. 
In this consideration we have presupposed that the 
lines of direction emanating from the end-points of the 
same object, which has to remain at the same distance, 
are parallel, and this supposition may be made with suf- 
ficient accuracy. The letters of Sn. xx are 9,5 mm. high, 
they are seen at a distance of 20', that is, 6496,9 mm. 
The first nodal point of the emmetropic eye lies 6,957 
mm. behind the cornea, that of the aphakial eye, when 
armed with +3, lies 5,475 mm. behind the cornea. If 
from an elevation of only 9,5 mm. above a straight 44 
basal line, other straight lines are drawn to two points 
of the same basal line at a distance of 6497 mm. from 
the point of origin, and only 0,3 to 3,0 mm. from each 
other, these lines will be sufficiently parallel to each other 
for all ordinary purposes. To satisfy myself of this 
fact, I have calculated the visual angles formed in 
emmetropic eyes and armed aphakial eyes by letters of 
Sn. xx seen at 20'. If we call the visual angle v, its 
9 5 
tangent will be, in the emmetropic eye, and in an 
9 5 
aphakial eye, when armed with + 4, = g-Qg-Q ' The 
logarithms of the tangents of these angles differ only in 
the fifth decimal, and show in both cases an angle of five 
minutes. This angle remains the same also for the 
strongest lens, + that may ever be put before an apha- 
kial eye. The logarithms of the tangent of its visual 
angle and that of the emmetropic eye differ by 0,00022, 
whilst the difference of the logarithms of the tangents of 
an angle of 5 minutes and 0 second, and those of an 
angle of 5 minutes and 1 second is 0,00134. From the 
foregoing considerations it ensues 'that the movement of 
the first nodal point by spectacle glasses exerts no ap- 
preciable influence on the size of the smallest visual 
angle as used in our common test-types, since its greatest 
movement, produced by + causes a change in the 
size of the visual angle not exceeding } of a second. 
Thus far I have shown, in a general way, and illus- 
trated by an example, what alterations are brought about 
in the optical system of aphakial eyes armed with spec- 45 
tacles. I have demonstrated, moreover, what influence 
spectacles have on visual acuteness when the latter is 
tested in the manner now in general practice. Since 
both the changes of the optical constants and of visual 
acuteness deserve to be known, I have calculated them 
for the usual cataract glasses; and collected them, for 
the sake of reference, in the subsequent table. 
The letters at the heads of the columns have the 
following meaning :— * 
No = focal length of glass in Paris inches. 
Fx = first focal length of apliakial eye armed with 
lens named in first column. 
N = second focal length of compound system. 
Ax = Axis of aphakial eye requiring for distant vision 
lens indicated in first column. 
IIX K% = distance between first principal and first nodal 
points. 
Hx If = If If = mutual distance of principal or nodal 
points. 
If — position of first, and II\ of second principal point 
behind the cornea. A — sign indicates that they lie be- 
fore the latter. 
If and If = position of first and second nodal points 
behind the cornea. 
Co-ef. = Co-eflicient of magnifying power. 
Sn. xx in feet, at what distance, in Paris feet, Sn. 
xx should be read wdien S = 1. No. 
Pi. 
Fa. 
Ax. 
Hi K,. 
Hi Ha. 
H 
If 
2 
H 
3 
H 
4 
5 
6 
18,300 
19,080 
19,485 
20,202 
20,701 
21,089 
21,384 
21,809 
22,113 
24,596 
25,525 
26,063 
27,024 
27,681 
28,210 
28,605 
29,172 
29,565 
17,324 
19,193 
20,286 
22,232 
23,599 
24,637 
25,435 
26,586 
27,381 
6,296 
6,445 
6,578 
6,802 
6,990 
7,121 
7,221 
7,363 
7,452 
4,536 
3,996 
3,646 
3,024 
2,577 
2,254 
2,001 
1,632 
1,389 
* 
- No. 
\ 
Hi. 
Ha. 
Kj. 
Ka. 
Co-ef. 
Sn. xx. 
in feet 
n 
if 
2 
H 
3 
3* 
4 
5 
6 
- 2,736 
- 2,336 
- 2,131 
- 1,768 
- 1,515 
- 1,318 
- 1,169 
- 0,954 
- 0,795 
- 7,2720 
- 6,3316 
- 5,7769 
- 4,7917 
- 4,0917 
- 3,5730 
- 3,1700 
- 2,5864 
- 2,1843 
3,560 
4,109 
4,447 
5,034 
5,475 
5,803 
6,052 
6,409 
6,657 
-0,976 
0,113 
0,801 
2,010 
2,898 
3,549 
4,051 
4,777 
5,268 
1,8390 
1,6149 
1,5124 
1,3595 
1,2758 
1,2216 
1,1839 
1,1351 
1,0801 
36,78 
32,30 
30,25 
27,19 
25,52 
24,43 
23,68 
22,70 
21,60 47 
LARGE CYST OF TIIE IRIS, CURED BY OPERATION 
By H. KNAPP. 
The literature of cystic tumors of tlie iris is yet very 
fragmentary. J. W. Hulke (Ophth. Hosp. Rep., Vol. VI., 
1, p. 12) and L. Weaker, in his Etudes Ophthalmologiques 
(I., p. 426), and in a paper in these Archives (I., 1, p. 
85), have given the fullest accounts of what is known on 
this subject. Since especially the clinical part of cystic 
tumors originating in the iris is as yet most defective, I 
think that the description of the following case may not 
prove destitute of interest and practical utility. 
Cecile Delaliaye, from Burlington, Iowa, eleven years 
of age, was injured, eighteen months ago, with a knife, 
the point of which entered her left eye just at the corneo- 
sclerotic juncture. The pupil became pear-shaped, the 
sight, for some days impaired, returned nearly as good 
as that of the other eye. A black, elevated spot at the 
seat of the wound was always visible. The eye was 
free from pain and annoyance. Eight months ago, how- 
ever, the father observed that a thin gray membrane had 
formed in the eye directly under the scar, and was grad- 48 
ually increasing in the direction of the pupil. Four 
months ago he perceived that a similar membrane de- 
veloped itself on the other side of the pear-shaped pupil. 
Both were growing steadily, and slowly approached 
each other, until they coalesced, assuming a heart-shaped 
figure. The sight had been impaired, and the eye, of late, 
became from time to time red and painful. 
The patient, a tall healthy girl, presented herself to 
me on the 31st of May, 1869. Her right eye was nor- 
mal in appearance and functions, and had never expe- 
rienced any alteration. The left showed some episcleral 
injection, most marked towards the nose. On the sclero- 
tic border, a little inward from the upper end of the 
vertical corneal meridian, was a small bluish elevation of 
three millimetres in length and two millimetres in 
breadth (a Fig. 5). Through the normal cornea a 
Fig. 5. 
transparent cyst was, at first glance, visible, filling the 
upper four-fifths of the anterior chamber. It left a small 
piece of healthy iris, on the lower part of the chamber 49 
(irf uncovered, and about a quarter of tlie normal size 
of the pupil was free and perfectly black (y>). 
The cyst itself appeared as a transparent, homogene- 
ous, somewhat grayish bag, filled with clear water. The 
coloboma and iris could be seen through it. The whole 
anterior surface of the cyst appeared to be in immediate 
contact with the cornea, whilst its inferior border was 
round, and formed an angle in the pupil (a). Its upper 
and outer part lay upon the iris, which it pushed back- 
ward (b). The surface of this part of the iris, visible 
through the cyst, displayed a grayish discoloration, but 
was smooth, with quite a regular pupillary edge. On 
the upper corneal margin there existed a small, slit- 
shaped iridodialysis (0, Figs. 5 and 6). Entirely differ- 
ent was that portion of the iris bordering on the inner 
side of the coloboma. It was very much pushed back- 
ward, and showed two cup-like depressions (<?, d), each of 
which was confined, inferiorly, by a curved projecting 
ridge of iris tissue. The lower of them formed the 
boundary of the preserved healthy part of the iris. The 
surface of the depressed portion of the iris appeared 
dirty gray, and even black in the upper part, which also 
exhibited the deepest cup. The pupillary edge was ele- 
vated, forming, along the whole inner border of the 
coloboma, a septum (s) with antero-posterior direction 
slightly bulging towards the coloboma. Its margin did 
not reach the posterior surface of the cornea, but was 
overlapped by the outer portion of the cyst. Inward 
from the coloboma, especially in the upper cup, the tis- 50 
sue of the iris appeared rarefied, and the black pigment 
of the uveal layer became visible through the cyst. 
My opinion was that this cystic tumor had its origin 
in that portion of the tissue of the iris which was in- 
volved in, and attached to, the corneo-scleral cicatrix. 
It had first grown within that portion of the iris which 
lay inward from the coloboma. Its anterior wall soon 
projected over the anterior surface of the iris, extended, 
in its upper part, over the pupil and the outer portion 
of the iris, and became so much filled that it touched 
the posterior surface of the cornea, and crowded the 
iris and lens backward. The tumor was evidently still 
progressive. 
All the cysts of the iris which have been recorded up to 
this day (about 22 in number) were, when left untouched, 
destructive to the eye, and several of them even caused sym- 
pathetic inflammation of the other eye. I therefore was 
convinced that nothing but an early operation could 
save the eye of the patient, and my opinion was con- 
firmed by further examination. 
The eye was painful to the touch, exhibited a manifest 
increase of tension, which remained unvariable during 
the four following days. S = M = T’T. The other 
eye w~as emmotropic; the O S revealed nothing remark- 
able in the fundus of either eye, especially no staphy- 
loma posticum of the left. The myopia of this eye was 
surprising, in consideration of the fact that iris and lens 
were considerably pushed backward, which condition of 
itself evidently would have rendered the eye hyperopic. 51 
This, however, did not take place, but just the contrary, 
which may be explained in the following way. The 
cyst pressed forcibly on the lateral portions—except 
the lower one—of the lens, and thereby caused a bulging 
of that portion of the anterior lens surface which was 
not covered or pressed upon by the tumor. A circum- 
scribed augmented convexity of the anterior capsule 
must have been produced to such a degree as not only to 
counterbalance the optic effect of the retrocession of the 
lens, but even to cause considerable myopia. 
The nature of the disease, and the painfulness, in- 
creased tension, and impaired sight of the eye, forced the 
unswerving conviction upon me that the eye was sure to 
be destroyed unless the growth of the cyst were checked. 
To expect this from anything else but an operation, 
could not be thought of. Puncture of the cyst would 
surely have been followed by a recurrence. The removal 
of the whole cyst seemed impossible without rendering 
the operation too perilous by the extent of the wound. I 
therefore concluded to take away as much of the tumor 
as I could without exposing the eye to a greater dan- 
ger than is borne safely in ordinary operations. If a 
recurrence should follow, I imagined, then the incipient 
state of the refilling cyst would show a tumor smaller and 
easier to remove totally by a subsequent operation. I 
operated in the following way. With a broad lance- 
shaped knife I made an incision at the inner side of the 
corneo-sclerotic juncture, near the corneal margin, but 
within the sclerotic border. The inner portion of the 52 
cyst, of course, was penetrated and emptied by the knife. 
Introducing a pair of delicate iris-forceps, and trying 
to seize that piece of the cyst which lay over the pupil 
and the outer part of the iris, I found an insurmount- 
able obstacle in the vertical septum (s, Fig. 5). I there- 
fore seized the latter by widely opening the branches of 
the forceps, and, after closing them, I had the pleasure 
of seeing the whole inner part of the iris come out. 
Cutting it off close to the wound produced a wide 
coloboma, in which none of the inner part of the iris 
remained behind. The condition of the eye, after the 
operation, is represented in Fig. 6. The uncovered part 
Fig. 6. 
of tlie pupil, which before the operation had been small 
and triangular (p, Fig. 5), had enlarged to a broad 
stripe, reaching the inner margin of the cornea (p, Fig. 6). 
The broken wall of the outer cyst still covered the outer 
part of the iris (b), and its lower border (pi, Fig. 6) 
stretched across the upper pupillary space nearly as 
far as the inner corneal margin. In seizing the septum I 
had caught hold of the overlapping portion of the outer 53 
cyst, and dragged it necessarily towards the wound, in 
which, however, it was not involved. 
A moderate degree of irritation followed the operation. 
Tolerably well marked circumcorneal injection, and 
some swelling of the border of the upper lid on the fol- 
lowing day, were symptoms not altogether pleasant, 
but they were counterbalanced by the total absence of 
pain, and normal appearance of the lower part of the 
iris. I abstained, therefore, from any severer treat- 
ment. The eye recovered very rapidly. Ten days 
after the operation a slight protrusion of iris in the 
corner of the scar of the iridectomy wound was notice- 
able, which increased somewhat during the following 
days, representing a condition which we not infrequent- 
ly see after large excisions of the iris in operations for 
glaucoma or extraction of cataract. The sight of the eye 
was greatly improved, the tension of the globe lessened, 
but in the upper part of the pupil there seemed to be a 
renewed and circumscribed swelling (/i, Fig. 6) of the 
cyst, the walls of which, up to that time, had lain 
shrivelled up and flat upon the lens and outer part of 
the pupil, the anterior chamber having been, soon after 
the operation, fairly re-established. Since this swelling 
threatened to cause a refilling of the cyst, and in any 
case darkened a considerable part of the pupillary field, 
I decided to remove it, if possible, together with as 
much of the adjoining part of the iris as I could, by 
another outward and upward iridectomy. After having 
made a broad incision at the upper and outer corneal 54 
margin, I introduced a blunt (Tyrell’s) hook in front of 
the iris and remaining part of the cyst, as far as to bring 
the point of the instrument behind the inner edge of the 
cyst. I grasped with the hook the peripheral portion of 
the cyst near the point m, and proceeded to draw it out 
in the direction towards b (Fig. 6), together with the 
iris beneath it. At first the cyst followed nicely, sepa- 
rating itself from the capsule of the lens, but its attach- 
ment to the upper part of the primary coloboma and to 
the scar did not give way, so that the tissue of the cyst 
was ruptured, and only the middle portion of it extract- 
ed and cut off with the iris. By means of forceps and a 
sharp iris hook I attempted, with great care not to 
wound the lens-capsule, further to remove the upper and 
lower remnants of the cyst, but succeeded only partially. 
After having done this, I excised the small prolapse of 
iris in the corner of the first iridectomy wound (r, Fig 6). 
The operation was followed by no pain, but the globe 
became red, and the upper lid swelled. No remedy was 
administered except atropine. The eye recovered rapid- 
ly from the operation, sight improved, and the small 
remnants of the cyst shrivelled up, resembling patches of 
connective tissue. A week after the operation the very 
lively young patient, having been imprudent in walking, 
and eating more ice-cream than was good for her, felt 
feverish and sick, and vomited several times. She had 
some pain in her eye, and an abundant running of tears. 
I did not see her till the following day, and found the 
eye red again, the anterior chamber quite empty, and the 55 
iris greenish discolored. I ordered six leeches to be put 
in the temple, and kept her in bed for two days, 
having atropine dropped into her eye every hour. The 
iritis at once subsided, the anterior chamber slowly re- 
filled, the visual field, which had become densely clouded, 
cleared up again, and at the end of five days the conse- 
quences of this inflammatory attack had disappeared. 
A week later, that is, three weeks after the second, and 
five after the first operation, the patient returned home, 
her eye being in the following condition. It was still 
very sensitive to brilliant light. Vision A, having been 
sj before the first operation. The myopia had disap- 
peared. She could read Sn. CC at 20' distance, and said 
that concave glasses made the letters no clearer, whilst 
convex glasses made them blurred. F was normal, and 
T no longer increased. Subconjunctival vessels were 
still somewhat injeeted. The cicatrix from the first 
iridectomy showed again a small prolapsus iridis in the 
Fig. 7. 
lower corner, and there seemed to exist some tendency to 
cystoid protrusion of the cicatrix. The second iridec- 56 
tomy wound was firmly united ; the outer surface of the 
cornea clear and sensitive; its inner surface, however, 
showed in its upper inner part (<?, Fig. 7) some dark gray- 
ish spots, like connective tissue, probably the remainders 
of the shrivelled cyst having become attached to the cor- 
nea during the evacuation of the anterior chamber. The 
lower and outer portion of the iris (tr, Fig. 7) appeared 
quite normal, only the corner (y, Fig. 7) bordering out- 
wardly on the coloboma was still covered by a delicate 
grayish membrane, being the last remnant of the cyst 
wall. The lens was transparent throughout, but some 
opacities upon the capsule had remained behind. It 
seemed to be somewhat pushed forward, the anterior 
chamber having not yet regained its natural depth. The 
interior of the eye could be well illuminated, but I was 
unable to distinguish the details of the fundus on ac- 
count of the irritability of the eye.' 
I should have been glad to remove the last remnant of 
the cyst, together with the small part of iris beneath it, 
but at the second operation it was not possible to 
excise it without giving the wound such an extent as to 
endanger the eye. To take it away now, three weeks 
after the second operation, did not seem advisable either, 
since the endurance of the eye for further operations, as 
well as the patience of the little sufferer, appeared to be 
exhausted. Apart from this, the refilling of the cyst 
could not be predicted with any degree of probability. 
If it should occur, which was no more than a mere pos- 
sibility, less supported by the analogy of similar observa- 57 
tions than apprehended by our sympathizing care for 
the amiable young patient, an ultimate operation in 
order to take away the small remains of the cyst would 
not have been so perilous as either of the preceding ones. 
I examined the pieces of iris and cyst which had been 
removed by the first operation. The iris had preserved 
its natural structure, showing no degeneration, but some 
degree of atrophy. Upon it lay the delicate cyst-wall, 
composed of flat, very large, polygonal epithelial cells. 
Fig. 8. 
I could not make out a basement membrane between 
these cells and the iris, but a piece of the free wall of 
the cyst exhibited the parallel and winding lines char- 
acteristic of homogeneous membranes, for instance, the 
glassy membrane beneath the pigment epithelium of the 
choroid. Therefore it was evident that the wall of the 
cyst consisted of a delicate lioynogeneous (glassy) mem- 
brane lined with pavement epithelium. Its contents were 
entirely transparent and fluid, like water. They could 
not be gathered during the operation, although I tried 
to obtain them. 
The origin of cystic tumors of the iris has been much 
discussed of late. There are three opinions on it:— 58 
(1.) They are said to be the dilatation of pre-existing 
free spaces in the iris. (2.) They are regarded as new 
formations, a conclusive illustration of which is furnished 
by the highly interesting observation of Yon Graefe, 
relative to a dermoid cyst in the iris containing athero- 
matous matter with short stiff hairs (Arch. f. Oplithalm., 
III., 2, p. 412, and ibidem, VII., 2, p. 39). (3.) They are 
supposed to develop by a process of sacculation in such 
a way that by adhesive inflammation, especially after 
penetrating wounds, the iris becomes attached to some 
part of the walls of the anterior chamber. If in such 
cases a free space between the attached parts is left, the 
secreted fluid will increase it to form a pouch, which by 
subsequent formation of a new wall will become a true 
cyst. This opinion, strongly advocated by L. Weaker, 
accounts best for the origin of the cyst in the case just 
described. 
The unfavorable side of the prognosis of the latter 
depends upon the possibility that the last piece of the 
cyst left behind may become the starting-point of a re- 
currence, and besides that, in the predisposition for glau- 
coma in eyes with anterior synechise. A tendency 
to serous effusions is manifested in this eye by the 
cystoid cicatrix at the place of the primary injury, and, 
perhaps, by the small portion of iris involved in the 
lower angle of the first iridectomy wound. The large 
coloboma, however, and the youth of the patient, will, 
I suppose, counterbalance this tendency. As to the pos- 
sibility of a recurrence, I think that what we know on tliis subject does not speak for its probability, since 
iris cysts did not reappear even after simple paracentesis, 
or after removal of tlieir anterior (free) wall, whilst in 
the case under consideration only a very small part of the 
cyst wall, and the iris beneath it, is left behind, but the 
bulk of the tumor, and all the iris with which it was con- 
nected, are taken away. 
Since I wrote the foregoing, which was at the time of 
the patient’s discharge, I have had repeated information 
with regard to her health. The eye has completely re- 
covered, there is no irritability of either eye, and no 
cystoid protrusion of the wound has developed. The 
lower part of the iris is somewhat drawn upward, en- 
croaching upon the clearest portion of the pupil; vision, 
however, so far restored that ordinary print can be read 
with the injured eye. This was the condition of the pa- 
tient according to the latest information, which I re- 
ceived a few days ago,—seven months after the opera- 
tion. CASE OF EXTIRPATION OF A CANCROID GROWTH OF THE 
INNER CANTIIUS AND UPPER EYELID. BLEPIIARO- 
PLASTY BY SLIDING FLAPS. 
By H. KNAPP. 
The unsatisfactory results obtained in many cases of 
blepliaroplasty by transplanted flaps of skin, due to sub- 
sequent contraction and thickening, with very unpleasant 
consequences, induced me, during the last few years, to 
cultivate more the method of the sliding of flaps. My 
experience in this direction has been so far very en- 
couraging. Two extremely satisfactory cases I have 
published a short time ago, the one in the “Arch. f. 
Ophthalm.,” XIII., p. 180, etc., and the other in the first 
number of the Archives of Ophthalm. and Otology, p. 
139. 
The following case is analogical to the two preceding 
ones, but offers peculiarities with regard to the mode of 
operation which may prove useful in the treatment of 
similar difficulties:— 
Sea-Captain M., of Scotland, 45 years of age, healthy 61 
and robust, observed about two years previously a small, 
hard, circumscribed elevation in the skin of the upper 
eyelid and the inner canthus. It gradually increased, 
was surrounded by other nodules, and constituted, at the 
time Tvhen he came to me, August 23d, 1869, a nodular 
thickening of the skin upon and above the inner canthus 
(see Fig. A), twelve millimetres in breadth and thirty 
Fig. A. 
in length. The tumor was felt by the exploring linger 
as a dense mass receding into the orbit, but without firm 
attachments to the bone. Since it presented all the 
qualities of a cancerous growth, the patient agreed at 
once to its removal by an operation, which advice had 
been already given to him by some other physicians. 
I circumcised it by a curved and angular line fully 62 
within the healthy skin (abed), and dissected it care- 
fully and slowly through the healthy tissue of the orbit, 
guiding my steps always by the exploring forefinger of 
my left hand. The ligamentum canthi, being quite un- 
affected, could be spared, but above it I found the tumor 
penetrating into the orbit about half an inch, so that 
after its removal a considerable hole was visible. The 
inner portion of the cartilage of the upper lid had 
been taken away. The defect of skin which reached 
from below the inner canthus and the root of the nose 
obliquely upward and outward as far as the eyebrow, 
and a little beyond the middle of the upper lid, was 
covered by sliding flaps in the following manner:—A 
straight cut, a e, was made through the skin horizontally 
over the back of the nose, in prolongation of the lower 
border of the wound a b. Another straight cut, df, went 
through the skin from the inner upper orbital angle towards 
the brow of the other eye. The flap comprised between 
these two lines was dissected from the original wound 
towards its basis, which lay on the other side of the nose. 
Next I dissected the inner portion of the lower lid, b, 
from the subcutaneous tissue of the conjunctiva, and se- 
parated, to the extent of some lines, the skin of the upper 
lid along the wound b e from the orbicularis muscle and 
cartilage. I then united the lower end, a, of the nasal flap 
with the inner end, b, of the lower lid, which caused consi- 
derable stretching of the latter and the flap. The lower bor- 
der of the flap was united by silk sutures with the adjacent 
skin without marked puckering of the latter. Then the 63 
inner part, i, of the upper lid w~as fastened to the opposite 
border of the nasal flap. The wound now looked as re- 
presented in Fig. B. A simple stitching together of the 
Fig. B. 
upper lid and the nasal flap could not be thought of, 
because it would have occasioned a very disfiguring 
ectropion. To make a cut through the upper lid, par- 
allel to the margin of the lid, and shifting the latter 
towards the nose as far as to reach the flap, was quite 
impracticable, because the tendon of the levator muscle 
must be preserved lest incurable ptosis be the conse- 
quence. For this reason the method which I have very 
successfully applied to the lower lid, is not applicable to 
the upper. To obviate both these difficulties, ectropion 
and ptosis, I made a vertical cut, n m (Fig. B), from the 64 
inner upper angle of the wound, about three-quarters of 
an inch in length. Now I dissected otf the skin situate 
above the wound, and fitted the angle mn c into the angu- 
lar defect die (Fig. B), uniting the edge n c with i c, and 
the lower part of n m with the upper part of the vertical 
margin of the nasal flap. The remaining small trian- 
gular defect, d n m (Fig. B), was covered by loosening 
from its base the triangular flap of skin rn n f lying 
above the quadrangular nasal flap, and by uniting its 
edges with the opposite edges of the remaining triangular 
defect. 
Fig. C. 
In this manner the whole wound was closed, and the 
region of the operation had the appearance which is re- 
presented by Fig. C. Both eyelids were stretched 65 
towards the nose, a slight degree of eversion of the inner 
margin of the npper lid existed, and the transplanted 
portions of skin, now situate over the inner cantlius, 
stretched over a hollow space, the former seat of the 
orbital portion of the tumor. I considered this hollow 
space a favorable condition, presupposing that the cica- 
tricial tissue which was to fill it up would draw the 
skin bridging loosely over it, backward into the orbit. 
This expectation was fully realized. There was but 
trifling suppuration in this space. The whole wound 
healed by first intention, and the slight degree of ever- 
sion of the inner portion of the upper lid entirely disap- 
peared, in consequence of the retraction of the cicatrized 
tissue near the inner canthus. The upper lid was per- 
fectly movable, and the palpebral fissure closed easily 
at will and during sleep. Epiphora was the only thing 
the patient had to complain of. The interference with 
the canaliculi and the removal of the m. compressor sacci 
lacrymalis were the unavoidable cause of this not very 
material annoyance. 
About a fortnight after the operation the patient was 
presented to the Medical Society of the County of New 
York, when he was examined by the scrutinizing eyes of 
the most experienced surgeons of the metropolis, who 
pronounced the result of this blepharoplasty as the most 
satisfactory that could have been obtained. A week 
afterwards the patient went on board ship again, and, 
four months later, he wrote to me that his eye continued 66 
in excellent condition, showing no disfigurement or annoy- 
ance, except simple lachrymation. 
On microscopic examination I found in the specimen 
the ordinary structure of epithelioma. Its peripheral por- 
tions were very vascular, and consisted mainly of smaller 
epithelial cells densely interspersed with lymph cor- 
puscles, which penetrated also in large quantities into the 
neighboring connective tissue of the orbit. The epithelial 
cells of the growth were accumulated by homogeneous 
juxtaposition, presenting but rarely the well-known cone- 
like figures. In some places the large epithelial cells 
were very distinctly serrated (Stachelzellen), and, with 
an immersion system, the small projecting bristles or 
hairs could be clearly seen not only at the border of the 
cells, but on their surface. 
From the abundance of blood-vessels, and the infiltra- 
tion of the tissue around them with lymphoid bodies, 
the following inference concerning the mode of develop- 
ment of the growth may be made : the lymphoid bodies 
were white blood corpuscles having transuded through 
the walls of the capillary blood-vessels; they, being 
movable, infiltrated the surrounding connective tissue, 
and developed in the mucous layer into epithelial cells. -A. COlVCIPniiETEl 
MANUSCRIPT 
business 
DIRECTORY 
OF THE 
UNITED STATES 
HAS BEEN COMPILED BY THE MERCANTILE AGENCY 
OF 
,T. ARTHURS AtirItHIIA' .Sr CO. 
EACH BUSINESS IN A SEPARATE MANUSCRIPT 
REGISTER. EVERY LIST COMPLETE AND 
ACCURATE. VALUABLE STATISTICS 
AND INFORMATION SUPPLIED. 
Circulars and Envelopes Addressed from these Lists to reach any part 
of the country. Also, this or other Cities. 
]. ARTHURS MURPHY & CO., 
Mercantile and /Statistical Agency, 
I I I NASSAU STREET, NEW YORK. 
Circulars Addressed to persons in any line of business, Manufacturers or private 
citizens, as may be desired. We distribute in New York City through Hussey’s 
Express Post or the Post Office, as we are ordered H$»|i!cle jfe §|tf»£$lU iCisfs 
OIF 
FARMERS A! PLANTERS, 
PHYSICIANS, 
Deatlsts, Druggists 
or* 
Persons engaged in every other line of busi- 
ness in the United States. 
Envelopes or Wrappers addressed to reach, parties 
engaged in any profession, manufacture or trade. 
J. ARTHURS MURPHY & CO., 
Ill Nassau Si., 
New York City. 
Correspondents wanted in every town and village in the United States. 
Persons of reliability only will be treated with. The information required is re- 
garding the extent of manufactures, and the names of the person or persons carry- 
ing on such—say Woolen, Cotton, Flour or Paper Mills—Breweries, Foundries, 
Tanneries, Machinists, and such like. Also names of leading store-keepers, and 
kind of goods they sell, as Dry Goods, Groceries, Hardware, Books, Jewelry, Sta- 
tionery, Tobacco, Drugs ; also Dentists, Physicians, Farmers or Planters, or what- 
ever may be their trade or profession. 
It is desirable to give some discrimination as to the extent of the various mer- 
chants—whether they are the most extensive in their line—or are second rank, 
third rank, fourth etc., in extent. 
It is necessary to have also their rank as to credit and reliability and whether 
they own real estate—length of time in business—or any such brief information 
as can be given. 
Arrangements as to these particulars can be made with qualified persons, 
after corresponding with us, but need not interfere with any list of names and ad- 
dresses being sent previous to such special agreement.