OPHTHALMOMETRY WITH THE OPHTHALMOM- 
ETER OF JAVAL AND SCHIOTZ, WITH 
AN ACCOUNT OF A CASE OF KERATO- 
■r \ CONUS 
BY 
SWAN NT. BURNETT 
WASHINGTON 
(Reprinted from the Archives of Ophthalmology, Vol xiv Nos 2 and 
3. 1885.J OPHTHALMOMETRY WITH THE OPHTHALMOM- 
ETER OF JAVAL AND SCHIOTZ, WITH AN 
ACCOUNT OF A CASE OF KERATO-CONUS. 
By SWAN M. BURNETT, Washington. 
(With three wood-cuts.) 
JAVAL and Schiotz exhibited their perfected ophthal- 
mometer at the meeting of the International Medical 
Congress held in London in 1881. I have not been 
able to find, however, any published papers, embodying 
results of experimentation with the instrument by others, 
outside of two or three on the continent.1 
In England and America, so far as my knowledge of their 
ophthalmic literature extends, no publication has been 
made.3 
Having used one of these instruments in my daily prac- 
tice for some months, I feel it but due to the ingenious 
inventors, and hope it may be not without interest to the 
practical ophthalmologist, to place the results of my obser- 
vations on record. 
Any description of the instrument itself is not necessary 
here, since this is accessible in the papers published by the 
inventors in the Annales d'oculistiquc for Juil.-Aout, 1881 ; 
Mai-Juin, 1882; Juil.-Aout, 1882; and Jan.-Fev., 1883. 
These articles contain all that is necessary for a thorough 
understanding of the principles on which the instrument is 
built, the method of its construction, and the manner of 
1 Laqueur, Grdfe's Archiv, xxx., I, p. 99; Angelucci, Ann. di Ott., xiii., 
fas. i., p, 35. 
5 Juler (Bnt. M. J., 1884, ii., p. 1274) speaks disparagingly of the instru- 
ment. 
Reprinted from the Archives of Ophthalmology, Vol. xiv., Nos 2 and 
3, 1885. 170 
Swan M. Burnett. 
using it. From a careful reading of them, no practitioner 
with a knowledge of the fundamental principles of optics 
can have any difficulty in taking the instrument from its 
packing-case, setting it up, and manipulating it with satis- 
faction. 
Its prime, and indeed only, function is the determination 
of the character of the corneal curvature.1 That is its limi- 
tation ; but when we consider that astigmatism is almost 
wholly corneal, and that it forms more than one half of the 
cases of refractive anomalies presenting for treatment, the 
importance of knowing the exact curvature of the cornea in 
all its meridians becomes apparent. 
The ophthalmometer does not give us the refractive con- 
dition of the eye as a whole, and furnishes no positive indi- 
cation as to the existence of myopia or hypermetropia,a but 
it gives with exactness the radius of curvature of the cornea 
in all its meridians; and, where there is a difference, it shows 
the direction of the principal meridians, and we can read on 
the instrument the amount of the difference in dioptries and 
fractions. The inventors claim that a difference of 0.25 D 
can be readily detected, and my own experience would sub- 
stantiate this statement. 
The main question is: Is it practical? I most unhesitat- 
ingly answer: Yes. Taking all things into consideration, it 
seems to me the most practical of all the instruments of 
precision we use in the diagnosis of astigmatism. I have 
found many ophthalmologists who have confessed that they 
did not rely on the ophthalmoscope in the diagnosis of 
refractive anomalies. That seems to be an art which all 
cannot learn ; but I can hardly imagine a practising oculist 
1 For which reason I think the term keratometer much more accurately de- 
scriptive than ophthalmometer. The term keratoscopie should be reserved for a 
simple inspection of the corneal surface without any measurements, as with 
Placido’s circles or Wecker’s square. 
4 Since writing the above, I have examined a case which demonstrates this 
very perfectly. In the left eye 110° had r = 7.8 mm.; 10°, r = 8.4 mm.; in the 
right eye 80° had r = 7.8 mm.; 170°, r = 8.4 mm. In both the bands crossed 
steps. When it came to correction, however, it was found that L required 
+ 1.25 (110°), while R required —1.25 (8o°). As the person was over sixty 
years of age, we could hardly suppose the existence of spasm of A in R. The 
M must therefore have been due to an elongation of the antero-posterior axis 
of the globe, of which fact, of course, the ophthalmometric measurements gave 
us no hint. I have also examined two cases in which M = 10 D existed in one 
eye, and E in the other ; but both corneae had the same radius of curvature. Ophthalmometer of Javal and Schiotz 
171 
that could not manipulate the ophthalmometer with success 
—certainly to the extent of detecting an astigmatism of o. 5 D. 
Another advantage is the rapidity with which examina- 
tion can be made. When the instrument is in position, it 
consumes even less time than an expert would take in 
making the same determination with the ophthalmoscope— 
that is, less than two minutes, including the reading and 
recording of the measurements. 
No other form of keratoscopy can compare with it for 
precision and accuracy. I have used Placido’s disc and 
Wecker’s square, but must confess that in regular astigma- 
tism I have found them worthless. They sometimes, in 
astigmatism of high degree, give indications as to the di- 
rection of the principal meridians, but I have never been 
able to estimate within two or three dioptries of the degree. 
It is in cases of astigmatism of high degree, and particu- 
larly in mixed astigmatism, where the instrument of Javal 
is of most essential value, for it is precisely in such cases 
that the subjective methods of examination are so tedious. 
With the ophthalmometer you obtain at a glance the data 
required for a speedy solution of the difficulty. 
I will not lengthen this paper by giving any tabular 
statistics, suffice it is to say that in about 100 astigmatic eyes 
I have not found a difference of more than 1 D between 
corneal and total astigmatisms, and that only in a single case. 
I will relate one case of kerato-conus in full, which not 
only shows the value of the instrument, but has also, I think, 
an interest and importance of its own. 
Mrs. R., twenty-seven years of age, says she saw well up to her 
sixteenth year. At that time her vision began to fail, and gradu- 
ally got worse until her nineteenth year, since which time it has 
remained about as it is now. On October 6, 1884, the time of the 
first examination, V = fjf. With — 6s she saw with either eye 
No. 60 at 4 metres, and no other spherical lenses gave further 
improvement. As is my habit, I then made an ophthalmoscopical 
examination before trying cylinders, since I thereby obtain at 
least some indications of the nature of the trouble, particularly if 
there is a high degree of astigmatism. On making this examination 
I at once found that I had to deal with a case of kerato-conus. 172 
Swan M. Burnett. 
Even in the inverted image it was not possible to see all parts of 
the disc clearly, and there was that excessive parallactic movement 
of the vessels which is so characteristic of kerato-conus when this 
method of examination is used. When the light from a plain 
mirror was thrown into the pupil from a distance, as in the shadow 
test,1 the peculiar unstable shadow crescent of conical cornea was 
beautifully shown. Examination by the direct method was in the 
highest degree unsatisfactory. At no time, and with no lens, 
could I get more than a part of two or three vessels in focus at 
once, and the least movement of the eye would throw those out of 
view and bring others forward. Some idea of the peculiar distor- 
tion of the vessels may be obtained from the accompanying dia- 
gram (fig. 1), which represents the disc as seen in the R eye, with 
FIG. I. 
4 behind the ophthalmoscope. The black lines represent the 
parts of the vessels which were seen distinctly; the shaded portion, 
the parts that were out of focus. 
The ophthalmoscope, therefore, which in cases of regular astig- 
matism of high degree is invaluable in giving us a clue to the 
character of the anomaly, was here of no avail. 
The average radius of curvature of the normal cornea is some- 
what less than 8 mm. In Mrs. R. the radius of curvature of the 
cornea was shortened in all the meridians, and in different parts 
of the same meridian, and a wide departure from the normal was 
found. The most nearly regular part was found, not directly in 
the line of vision, but about five degrees outwards in each eye. 
When in this position, the meridian in the R at io° had a radius 
of curvature of only 5.4 mm., and at no0 a radius of 6.8. The 
1 I think this name is preferable to keratoscopy, retinoscopy, pupilloscopy, 
phantoscopy, or any of the others that have been applied to this method of 
examination. Perhaps, for scientific nomenclature, we had better adopt the 
word skiascopy, as suggested by the French Hellenist, M. Egger. Ophthalmometer of Javal and Schiotz. 
173 
left cornea had a radius in about the same locality of 5 mm. in the 
meridian at 180°, and of 6 turn, in the meridian at 90°. Even in 
these meridians there was a rapid change in these figures as soon 
as the point of measurement was removed a few degrees from the 
place indicated. The shape of the bands became very much dis- 
torted, and it was impossible to take accurate measurements. It 
was very evident, however, that the corneal surface became flatter 
as it approached the periphery. The distortion began much 
sooner on the outer side of the point indicated in both eyes. In 
R I measured the radius in 180° at some 20 degrees out and in 
from the apex, and found it inwards 7.5 mm., and outwards 8 mm., 
The distortion was also greater in the upper 
than in the lower portion of the cornea. 
These measurements, while showing a very great irregularity in 
the corneal curvature, gave me an idea of the direction of the 
meridians of greatest and least refraction near the visual axis, 
which was of great value in my further unravelling of the tangled 
threads of evidence. I read off on the arc of the instrument that 
in L, 1800 had about 38 D, and 90° had 34 D—the difference 
being 4 D ; and when the bands were in contact at 90°, they 
crossed steps of the graded arc at 1800. In R, io° had 36 D 
(the normal being near 20), and no° had 30 D, and the bands 
were superposed 6 steps at io°, when they were in contact 
at 100.0 
These data gave me no hint of the character of the regular 
astigmatism, but I now knew the amount, and approximately the 
direction of the principal meridians. 
From the very short radius of curvature in all meridians, we 
naturally expected to find a high degree of myopia, but on testing 
with glasses it was found that while in L, with —- 9 — 4cy 180°, 
some letters of No. 12 were made out, in R some of No. 9 were 
seen, with + 4cy 180° — 90°. No. 1, of Wecker was read 
by both at 8 inches. It should be stated that the examinations with 
glasses were repeated many times, and under the full effect of 
atropine ; and the result as regards vision was the same with the 
same glasses, with and without the mydriatic. 
Javal has added a Placido’s disc to his instrument since 1881, 
and it has increased its value very much for the determination of 
irregular astigmatism. I had found the disc of Placido very 
useful for this purpose, and by it have discovered varying degrees 
of irregular astigmatism in many cases where V could not be Szva/i M. Burnett. 
174 
brought up to f# by any optical means. As we always have a 
certain and usually a very large amount of irregular astigmatism 1 
in kerato-conus, I made careful examinations of both eyes of Mrs, 
R with the disc. 
In fig. 2 is found the form of the disc at the corneal apex, 150 
upward and downward, and 20° on either side in the left eye. 
It will be observed in these figures that even at the apex 
there is quite a distortion below and to the outer side, while 
in all directions towards the base of the cornea the pe- 
ripheral portions of the rings are drawn out and flattened, 
indicating a great reduction of its curvature at this portion 
of its surface. The striking feature about these figures, how- 
ever, is their close approach to uniformity and similarity in 
form, indicating a much greater regularity of curvature than is 
usually found in conical cornea, and much more regularity at 
apex than the cornea of the case of recent extraction of the 
cataract shown in fig. 3. In fact, if we are to judge from 
these figures, the cornea approaches in form in this instance 
to an ellipsoid of revolution, though of course we know by 
ophthalmometer measurements that there is a compression 
laterally, as shown by the existence of so large an amount 
of regular astigmatism. Such a case would seem, theoreti- 
cally, to be well adapted to the use of hyperbolic lenses,. 
Fig. 2. 
1 See a paper by Angelucci in Ann. di Ottal., xiii., 84, fas. I. Ophthalmometer of Javal and Schidtz. 
175 
and I much regret that I did not have an opportunity of 
trying them. 
But the results obtained by cylindrical lenses are very 
gratifying, and encourage us to hope that with the aid of 
the ophthalmometer, many cases of kerato-conus, which 
have heretofore been deemed fit only for operation, will 
find a remedy in optical appliances.1 
In the R eye the images of the circles were even more 
regular in form than in the L, and there was much less dis- 
tortion at the apex of the cornea, and this is the eye which 
received the greatest benefits from the cylindrical lenses, 
vision being brought up to nearly 
I have made ophthalmometric measurements of three 
eyes on which I had operated for cataract by extraction. 
Unfortunately none of these eyes were so examined before 
the operation, but it is a fair assumption that both eyes 
were nearly alike when the patients so state. In one there 
was that rather rare accident of a reopening of the wound, 
nine days after the operation, and the examination was 
made only four days after it had again closed. At that 
time there was an astigmatism of 5.5 D in the meridian at 
450, corresponding pretty well with the place where the 
wound had given way, and the radius of curvature in that 
meridian was more than one millimetre longer than in the 
meridian at 135°. Examined fourteen days later, a marked 
change was found. 450 had now only 8.1 mm, while 1350 
had 8.4 mm radius, the difference amounting to 1.25 D, the 
shorter radius being now at 450. When a —(— 1cy with the 
axis at 45 was added to his cataract glass vision was much 
improved. In the second case the operation was a typical 
one, with Wecker’s incision wholly in the cornea. There 
was no reaction until the ninth day, when an iritis set in. 
1 he wound had closed perfectly, but cicatrization was not 
complete on the eleventh day, when I made opthalmometric 
measurements. The extraordinary degree of irregular as- 
tigmatism is shown by the distortion of Placido’s disc in fig. 
1 It now becomes a possibility that the hyperbolic lenses of Raehlmann, 
which have afforded decided advantage in cases of kerato-conus over cylinders, 
can be manufactured to order to suit each particular case from data furnished 
by the keratometric measurements. 176 
Swan M. Burnett. 
3. Combined with this there was also a very large amount 
of regular astigmatism, as indicated by the elongated form 
of the disc. 
On measuring the corneal curvature I found that 90° had 
r — 9.9 mm (n D) ; 180°, r = 8. (21 D); making a differ- 
ence of 10 D. The cornea of the other eye (which was 
also cataractous) was free from astigmatism of any kind. 
It is interesting to note that the other eye, operated on 
since thfe above was written, followed the same course, the 
iritis lasting six weeks. It was accompanied by analogous 
changes in the corneal curvature. Both corneae became sub- 
sequently almost normal in curvature. 
In another case, four weeks after extraction, in which 
there were no complications, either during or subsequent to 
Fig. 3. 
the operation, there was a corneal astigmatism of 2.25 D, 
the more strongly curved meridian being at ioo° ; and 
vision was much improved by the addition of this cyl. to 
this spherical. The fellow-eye showed no abnormality in its 
corneal curvature. Measurements ten days subsequently 
showed a decrease of the astigmatism to 1.5 D.1 
A number of accurate ophthalmometric measurements of 
eyes operated on for cataract by extraction, would give us 
valuable indications as to the kind of section which would 
be likely to give us a minimum of deformity in the corneal 
curvature. 
Another field for usefulness of the ophthalmometer will 
be in the selection of a place for making an iridectomy in 
cases of leucoma of the cornea etc., where there is left any 
choice of clear cornea. The instrument will show us at 
once which portion of the corneal surface is most nearly 
regular, and under that we can make the artificial pupil. 
1 See papers on this subject by L. Weiss, These Archives, vi., p. 432 
and Laqueur’s paper, /. c. g. p. putnam’s sons, printers 
NEW YORK