Elsevier

Ophthalmology

Volume 108, Issue 1, January 2001, Pages 76-80
Ophthalmology

Pattern visual evoked potential in the diagnosis of functional visual loss1

Presented in part at the American Academy of Ophthalmology Annual Meeting, Orlando, Florida, October 1999.
https://doi.org/10.1016/S0161-6420(00)00478-4Get rights and content

Abstract

Objective

To study the pattern visual evoked potential (P-VEP) in the diagnosis of functional visual loss.

Study design

Retrospective study of observational case series.

Participants

Seventy-two subjects whose best corrected visual acuity (VA) was 20/50 or worse, with or without visual field defect, and whose visual abnormalities could not be explained by the findings of ophthalmologic and neurologic examination were included in this study.

Main outcome measures

To compare the P-VEP estimated acuity to the initial subjective VA and to the best-performed VA.

Results

Seventy-two subjects with functional visual loss had normal P-VEPs. The initial subjective VA was 20/50 in 9 subjects and ≤20/200 in 42 subjects. After clinical examination and reassurance, the best-performed VA was ≥20/50 in 53 subjects and ≤20/200 in 8 subjects. The discrepancy between the P-VEP estimated acuity and the best-performed VA was less than 3 lines of Snellen acuity in 63 of 72 (87.5%) subjects and more than 4 lines in 6 subjects. These six subjects were three women with loss of vision of unknown origin and three men with injury-related visual loss.

Conclusions

P-VEP has the advantage of objectively predicting VA and is a useful test in the diagnosis of functional visual loss.

Section snippets

Subjects and methods

A retrospective study was performed on 138 subjects who were suspected of having FVL and referred to the electrophysiologic laboratory at the Vitreoretinal Foundation for VEP from 1991 to 1999. The records of these subjects, including medical history, clinical examination, visual fields (VFs), fluorescein angiography, ultrasonography, magnetic resonance imaging, computed tomography, x-ray studies, laboratory tests results, VEP, and consultant letters, were reviewed. Subjects were referred to a

Results

In a total of 72 subjects, unilateral visual loss was noted in 25 subjects and bilateral visual loss in 47 subjects. The VAs of both eyes were similar in bilateral visual loss subjects. The initial best-corrected subjective VA ranged from 20/50 to no light perception. The VA was 20/50 in 9 subjects and ≤20/200 in 42 subjects (Fig 1). The P-VEP estimated VA ranged from 20/30 to 20/100 and was 20/30 in 43 subjects, 20/50 in 25 subjects, and 20/100 in 4 subjects. Comparing the subjective VA and

Discussion

When a subject complains of vision loss or VF loss that is inconsistent with the physical, objective examination of the eye and visual system, FVL should be suspected. Ocular hysteria and malingering are two major forms of FVL. Hysterical amblyopia subjects manifest visual loss unconsciously. Some have underlying organic problems with functional overlay. Some show psychiatric or psychosocial problems, yet in most no origin could be disclosed.9, 10, 12, 13, 14 Malingering subjects often have

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    The authors have no proprietary interest in any of the materials used in this study.

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