The Value of the Ophthalmom- 
eter in the Determination 
of the Axis and the 
Amount of Astig- 
matism. 
BY 
LOUIS J. LAUTENBACH, M. D., Ph. D., 
PHILADELPHIA, 
Surgeon to the Pennsylvania Eye and Ear Infirmary; 
Chief of the Eye Clinic of the German Hospital. 
REPRINTED FROM 
Oe Neto York fHekical ^Journal 
for August 5, 1893. Reprinted from the New York Medical Journal 
for August 5, 1893. 
THE VALUE OF THE OPHTHALMOMETER 
IN THE DETERMINATION OF THE AXIS AND 
THE AMOUNT OF ASTIGMATISM. 
By LOUIS J. LAUTENBAOH, M. D., Ph. D , 
PHILADELPHIA, 
SURGEON TO THE PENNSYLVANIA EYE AND EAR INFIRMARY; 
CHIEF OF THE EYE CLINIC OF THE GERMAN HOSPITAL. 
The results herewith presented are drawn from the 
study of almost one thousand three hundred eyes with the 
ordinary tests (the ophthalmoscope, retinoscope, etc.) and 
the ophthalmometer, and the subsequent determination of 
the subjective refraction by mydriatics, either atropine or 
homatropine. 
My first experience with the ophthalmometer was with 
the Helmholtz instrument. This measured the corneal 
curvatures very accurately, but required quite a long sitting 
to complete the examination, sixteen readings being neces- 
sary for each eye. 
It is mainly on this account that it has proved to be a 
useless instrument in the working office, being, however, of 
great value for scientific research. 
Later (in 1892) I began to use the Java! Schibtz instru- 
ment, and now use it regularly in every case. Since I pur- 
Copyright, 1893, by D. Appleton and Company. 2 
THE OPHTHALMOMETER IN ASTIGMATISM. 
chased it I have examined the eyes of over six hundred 
patients. 
I consider the make of the instrument and its mode of 
use responsible for much of the difference in results of 
ophthalmometry, or rather, as it should be termed, kera- 
tometry. 
My instrument is one made by Meyrowitz, of New 
York. It is solidly constructed with a good metal base, 
and its head rest is attached by a metal support directly 
to the base; there is no vibration and no give to it; the 
parts are all fixed and firm. I have four sixteen-candle- 
power incandescent lights attached to the head-rest to illu- 
mine the disc. 
After the instrument had been constructed and delivered 
to me I had the arc set in proper position and the prisms 
overhauled by Mr. Seidel, of Philadelphia. After this was 
done the results were markedly more accurate than before, 
as the slightest deviation in the setting of the arc modifies 
the reading of the axis and the amount of astigmatism. 
The instrument is mounted on a firm typewriter stand 
with an overlapping leaf to give room underneath for the 
patient's knees as well as to give him a place to rest his 
arms and hands. 
In the barrel of the instrument on the center of the 
lens I have fastened a square of green paper of five milli- 
metres. This is a most necessary procedure, as by no 
other method have I been able to fix the patient's eye so 
well. 
Fastened to the head-rest of the instrument I have a 
pair of straps by means of which I prevent any forward 
or backward motion of the head. 
In order to have the patient's head and neck comfort- 
able when resting in the headpiece, I have a chair which I 
raise or lower to the proper height. THE OPHTHALMOMETER IN ASTIGMATISM. 
3 
In taking my readings I turn on the electric current, 
place the patient in the chair, raise it to the proper height, 
have him rest his chin on the chin rest and press his fore- 
head against the upper part of the rest, place his eyes 
at the proper height and see that they are on a level, 
tighten the straps just below the occipital protuberance, 
seeing that he is resting his feet firmly on the floor and his 
arms on the table; then, the spider's web being in proper 
position, T cover his left eye with the slide and direct him 
to look at the square in the barrel. 
I then focus the image accurately by raising or lower- 
ing the screw, pushing the barrel to the right or left and 
drawing it to or from my patient. I commence invariably 
with my indicator pointing to 90° and bring the mires in 
apposition at this point, the center of the line of apposi- 
tion being at the cross of the spider's web. 
If the central lines are not continuous I revolve to the 
right or left until they are continuous, and then again bring 
the mires into apposition. I then note this axis, and also 
the radius of curvature. 
I then turn the indicator just 90° from this, and if the 
lines are again continuous 1 note this axis and the amount 
of overlapping of the mires or their divergence; then again 
bringing the mires into apposition, I again note the corneal 
radius. 
If the lines are not continuous I revolve to right or left 
until they are so, and proceed as before indicated. I then 
examine the left eye in the same way. 
Usually the whole procedure-the examination of both 
eyes-will not take over three minutes, and the results are 
so accurate that subsequent examinations give absolutely 
the same results. 
I speak of this accuracy as I have noted others who in- 
dicate that frequent examinations are necessary. This ac- 4 
THE OPHTHALMOMETER IN ASTIGMATISM. 
curacy and time saving is, I think, the result of the per- 
fect illumination and the fixed and accurate position, as 
well as the ease and comfort in which the patient is placed. 
Occasionally I find a cornea very hazy. In these cases 
I use a drop of castor oil instilled into the eye, and, closing 
the lids, rub the eye very gently. Again I find the image 
becoming hazy while under examination. This is due 
occasionally to a lack of secretion, but more frequently 
to an excess. In these cases I direct the patient to wink 
two or three times or to close the eye for a few moments 
and then continue the examination. Occasionally when 
the arc is vertical or nearly so the image of the white 
parallelogram is either indistinct or it disappears; this is 
obviated by directing the patient to open his eye wider, a 
heavy eyelid being the cause of it. 
I am more and more convinced that Burnett's allow- 
ance of 0'5 D. as the difference between the astigmatism of 
the ophthalmometer and the subjective astigmatism is too 
high. I make an allowance of 0'37 D., subtracting this if 
the astigmatism is with the rule and adding it if against 
the rule. 
My cases have been so numerous and I have been so 
busy in many ways that I have not thoroughly analyzed 
them, but will here give you the results-the practical re- 
sults : 
1. That the ophthalmometer of Javal and Schibtz will 
determine the axis and amount only of the corneal astig- 
. * 
matism. 
2. That it will determine accurately the axis of astig- 
matism in between eighty and ninety per cent, of the cases. 
3. That in about forty five per cent, of the cases (mak- 
ing the correction of 0'37 D.) it will determine the amount 
of the astigmatism. 
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