Ocular Malingering
A Surprising Visual Acuity Test
Michael H. Graf, MD;
Jens Roesen
Arch Ophthalmol. 2002;120:756-760.
Objective To describe a visual acuity test for use in identifying psychogenic
visual impairment and malingering.
Methods The test contained 32 white plates with a black Landolt C printed in
the center. The sequence of the 4 alternative directions of the C was not
predictable. After plate 21, 4 circles were interspersed among the remaining
plates. The test is administered at a distance from which the subject is presumed
to be able to recognize the optotypes. He or she is requested to identify
the direction of the C within 2 seconds, and the responses are noted. Two
elements were evaluated: (1) The number of correct answers was compared with
the corresponding value of the distribution function of the binomial formula
that represents the probability of reaching this rate of correct answers by
pure chance. (2) The response to the first circle (appearing after plate 21)
was compared with the responses to the previous 19 Cs. The test was administered
to 20 volunteer pseudomalingerers and 15 patients believed to be true malingerers.
Results Malingering was detected in 14 (74%) of 19 volunteers included in the
evaluation and in 12 (80%) of 15 patients by too many or too few correct answers
to the stimuli or by their response to one of the circles.
Conclusions This test is useful in proving malingering. It may also provide evidence
of a minimum visual recognition acuity within the gross dimension of the actual
acuity.
From the Department of Ophthalmology, Strabismology, and Neuroophthalmology,
University of Giessen, Giessen, Germany.
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