Price, Wesley Dale

Turk, William

English

CommonKnowledge

Pacific University 
CommonKnowledge 
College of Optometry Theses, Dissertations and Capstone Projects 
5-25-1955 
Raubitschek test for astigmatism 
William Turk 
Pacific University 
Wesley Dale Price 
Pacific University 
Recommended Citation 
Turk, William and Price, Wesley Dale, "Raubitschek test for astigmatism" (1955). College of Optometry. 
200. 
https://commons.pacificu.edu/opt/200 
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Raubitschek test for astigmatism 
Abstract 
Raubitschek test for astigmatism 
Degree Type 
Thesis 
Degree Name 
Master of Science in Vision Science 
Committee Chair 
D.T. Jans 
Subject Categories 
Optometry 
This thesis is available at CommonKnowledge: https://commons.pacificu.edu/opt/200 
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Raubitschek Test for-Astigmatism 
Thesis Presented tc 
Optametrie Faoulty 
Faeifie University College of Optometry 
In Partial Fttlfil~ent ef 
Aeade.mic Requirements fer 
Deotorate Degree 
in Optometry 
By 
William Turk 
Wesley Dal e Prioe 
May 25, 1955 
543:10 
To the students Who served as observers and for their 
suggestions, we are obligated. We are grateful for the 
materials made available to us by Dr. D. Jans, Professor of 
Optometry and who assisted us in numerous ways. Finally, we 
are indebted to the publishers and authors whose works are 
referred to throughout t he follow:tng pages. 
Raubitschek Test for Astigmatism 
The purpose of this experiment was to devise a working model 
of the Raubitschek arrow test for astigmatism and to make a pre-
liminary study of the accuracy of the test. This study was limited 
to determining the variation in axis on test-retest of' 10 students 
of Optometl"J at Paci-fic University College of Optometry. 
Using an overhead projector, the photograph found on page 491 
of the American Optometric Association Journal, April. 1954, was 
. projected onto graph paper and diwmeter of the Raubitsehek arrow 
test chart arranged to equal the size of the clock dial chart 
projected at 18' by our A. 0. projector slides. Figure No. 1 is a 
sketch illustrating the photograph. The width of the black lines 
was made equal to the clock dial spokes. The dimensions were later 
increased to 1! times the clock dial when it was found. that acuity 
requirements seemed to be higher on the arrow chart. In the pre-
liminary study, the disk was revolved about a marking chart. Two 
types of disks are described in the literature; black on white and 
black, white and gray. (See Figures #1 and #2). The eurves were 
eonstrueted over the tracing and inked in by means of' drafting pen 
and .French curve~ A lens centering machine was redesigned such that 
an arrow disk could be rotated through 360° and pesi tion read to ]. 0 
in accuracy. This working model seemed to indiea.te very good 
aeeuraey could be obtained with the arrow and that of ·the two disks 
constructed, the black on white seemed to give better results. 
Shortcomings of the testing instrument were that the patient eould 
not adjust the final position of t he dial and, in general, the 
observers were sure that if they could move it, they eould have 
obtained greater accuracy. The second shortcoming was the time 
required to move back and forth between patient and wall during 
testing. With these criteria in mind, a slide was obtained which 
,. 
Page 2 
could be rotated through 180° and could be used with a olason 
projector. To obtain a negative which would be satisfactory for 
use in the projector$ it was neoessarf to photograph the chart 
used with the redesigned lens centering machine. The negative 
o.f this was again photographed such that the reverse negative 
obtained from this process would just fit the elason slide. 
(See Figure #4). A ehart was constructed and photographed and 
this provided a measuring device which could be worked by the pat-
ient and did not require that the experimentor move to and fro 
from test chart to observer. 
Patient was seated in refracting chai:r. Phoropter was intro-
duced before pattent's face and PD set for distance. Initially, 
the patient was monocularly fogged to 20/40 sn.ellen line of letters. 
Raubitschek dial was projected upon wall at 18' from patient and 
if' patient complained that the tip of the arrow was still indistinct 
in all positions, the fog was reduced .25 to .50 diopters. The 
apparatus was a.rranged in such manner so as to allow the patient to 
manipulate adjustment. The patient was instructed to retate the 
Raubitsohek dial until the narrow tip of the arrow appeared blacker 
than the 1JIIide wings of' the arrow. Patient was then instructed to 
rotate fUrther until a JND* was observed as one side of tip blacker 
than the other. Then rotate in opposite direction until the pGint 
of reversal. This systam of bracketing was repeated until the patient 
reported a shift from one side to the other with a rotation of less 
than 10°. Patient was then instructed to place the dial in such 
position that both wings were equally black as well as equal in 
length from tip ef arrow toward center of dial. The position of 
the arrow tip was then assumed to lay along the astigmatic .axis 
of least curvature, i.e. to indicate the axis of a correcting plus 
cylinder. 
*JND - Just Noticeable Difference 
Page 3 
To .find the amount of astigmatism., the examiner has to use 
two angles. These are a "test angle" for the temporary axis of 
the cylinder, and a "rotation angle" for position o.f' the arrow 
tip. The "test angle"and the "rotation angle 11 are obtained in 
the i'ollo>ring way: The test angle may be any angle chosen, and 
is usually 20°. Where the expected cylinder is high, say 250 D 
or more, a smaller angle may be used. Where the expected cylinder 
is low, say under 1.00 D, a larger angle may be used. 
The rotation angle is obtained from the test angle in the 
following way: If 11 a 11 stands for the te.st angle, then the retation 
angle equals 90 - a./2. I£' "a" equal 20°, rotation angle equals 
90- 20/2 C">r 35°. If "a" equals 10°, rotation angle equals 90- 10/2 
or 40°. If' "a" equals 30°, rotation angle equals 90 - 30/2 or 306 • 
Thus the three pairs of ang l es are: 
Test Angle 
1. 20 
2. 10 
3. 30 
Rotation Ang l e 
30 
40 
30 
for most eases, 1 • 250 
for high errors, 2.5 or higher 
correeting eylinder 
for low errors, to 1.00 
To find the runount of the required eylinder, the examiner made 
use <i>f the two angles, the "test angl e" and the "rotation angle". 
·As previously stated, these are usually taken as 20Q and 35°. The 
20° gives the pcuitien O·f the "temporary axis 1i and 35° gives the 
new position of the arrow tip. Both angles are taken Within t he 
quadrant I and II. The examiner notes on the scale of the dial 
(on the upper half of the dial) 20° from the true axis in the diree-
tion of ·the arrow tip, and arrived at the temporary axis. He rotates 
the arrow tip 35° toward the temporary axis and arrives at the new 
position of the arrow tip. The two wings of the arrow wil l now 
appear unlike. If the exwniner knows the approximate around of 
the cylinder required, he places that cylinder in the refractor. If 
he does not, he begins wi th no eylinder and adds cylinder in .25 D 
Page 4 
steps, at the "tempor.a:ry axis", until the patient reports the two 
wings are equally black, especially at the arrow tip . The cyl:i.nder 
should be increased or decreased to point ef reversal (first one 
side darker, then other side darker). until the addition or sub-
traction ef .25 diopter cylinder causes definite reversal. This 
then gives the correct amount of cylinder power. 
The refractor cylinder axis indicator is now rotated to the 
"True axis" position. 'rhe patient is instructed to notice and 
report any change or shift in equality of wings as the Raubitsohek 
dial is rotated throughout its entire eyole of 360°. 
Ten students volunteered to serve a s ebservers fer testing 
accuracy of axis. Whenever cylinder wa:s demonstrated during the 
first testing period, ten ebservations were made at different 
intervals. 
The results of eighteen monooular observations were grouped 
and analyized for the mean, mode and the sigma. This experiment 
was performed upon ten subjects. A total of 10 observations were 
recorded for eaeh eye. The data obtained was eompiled for mean, mode 
and sigma values. These data were recorded for both eyes of' eaoh 
observer in tables 1 through 10. Chart #1 presents the variations 
in t he sigmas of tables 1 through 10 in form of' a histogram. Chart 
Ne. 2 illustrates the variation between sigmas in the form a 
frequency polygon. 
Dif'fieulties encountered with the slide were that observers with 
minus astigmatiC- axis at nearly go• were not likely to get the re-
versal affect. This was because the excursion of the arrow was 
limited ,~.to an arc of 180° and would not occur in a slide whieh could 
be rotated the ful l 360c. Another problem which although it did not 
arise during the experimenting period, was yellowing of the slide 
Page 5 
breught abeut by the heat of the projector. It was not determined 
whether the glue or the negative was exhibiting the o0lor change. 
The discoloration seemed to be progressive, but did not seem to be 
evident on the projected image. The data presented in this study 
indicates the test may be useful as a clinical test to obtain the 
axis of a correcting cylinder in a distance prescription. The 
test eliminates some undesirable features present in sane of the 
presently accepted tests for axis and power. It doesnot depend 
upon an acuity judgment of letters for determination of axis er 
eylinder power; also selection of darker or lighter lines is 
limited to two adjacent curves and does not involve the confusion 
involved in charts such as the sunburst and clock dial. The testing 
device also tends to eliminate any preference for vertical or 
horizontal. 
The results of the testing seem to indicate that the astigmatic 
axis indicated by this test would normally .fall within a range ef 4.5 
degrees if the observer were to be retested for axis by this method 
at a later date. The preliminary study seems to indicate that ' 
gathering further data concerning the application af the Raubitsehek 
test for astigmatism would be worthwhile. Suggested studys are: 
1. Correlating the power found on test-retest ef a group of 
astigmatie observers. 
2. Comparing Raubi tsehek manifest cylinder against a clinically 
accepted means af determining cylinder and axis. 
3. Comparing the variations between a group of myopic astigmats 
against hyperopia astigmats. 
4. CQmparing variations on different dioptrie levels of 
manifest cylinder. 
References 
Journal of American Optometric Association, April, 1954, Vol XXV 
No. 9, Page 491. 
Optometric World, Sept, 1953, Vol. 41, No. 9, Page 22. 

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Raubitschek test for astigmatism

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Raubitschek test for astigmatism

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