Page 110 - The Indian Optician Digital Edition January-February 2022

the left hand letter with the right eye and
vice versa, and may well read only the letter
seen by the pretended blind eye and refuse
to acknowledge that they see the letter
with the sound eye.

 Show the patient a pair of fusion pictures
in the amblyoscope or synoptophore, e.g.
the rabbits. If he sees both the controls he
clearly has good vision in each eye. There
are also special slides- the flag series with
sentences on them which in order to make
sense, have to be read partly by one eye and
partly by the other. The size of the accurate
measurement of visual acuity can be made.
 Using the Javal series of stereograms in the
HOLMES Holmes stereoscope the patient is asked
STEREOSCOPE to read the print in front of his eyes. The
sentence can only be completed if both
causing the behavior must be ruled out. eyes are employed.
An optometrist will easily be able to detect
simulated uniocular blindness by conducting
one of the tests mentioned below: MALINGERING IS A VERY
 Place a light 6 metres in front of the PROBLEMATIC CONDITION
patient, and put a prism of 6°, base upward AND EVERY CASE
or downward, before the sound eye, if
the patient admits seeing double, it is an SHOULD BE HANDLED
indication that vision is present in both eyes. VERY TACTFULLY,

 With the light in the same position cover SENSITIVELY AND WITH
up the supposed blind eye. Then produce UTMOST PATIENCE
uniocular diplopia by moving 60° prism,
base upward or downward, until the apex
corresponds to the centre of the pupil. Next
uncover the blind eye, and at the same time
move the prism until it covers the entire pupil.
If there is still double vision then it is evident
that both eyes see.
 Place a strong convex lens (+ 12 D) before the
good eye and weak concave lens (-0.25 D) in
front of the supposed blind eye, and direct
the patient to read distance test types, if he
succeeds it is proof of malingering, since it is
impossible for him to see with the sound eye
when it is covered by the strong lens.

 Show the patient a picture or letters on the
Bishop Harman diaphragm apparatus taking
care that he keeps both eyes open. Patients BISHOP HARMON
frequently do not realise that they are seeing DIAPHRAGM TEST

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