The monocular vertical prism dissociation test

Document Type

Article

Abstract

PURPOSE: To determine if the monocular vertical prism dissociation test can differentiate between organic and nonorganic visual loss. DESIGN: A prospective, single-masked observational study. METHODS: Three institutional neuro-ophthalmology practices. Group 1 consisted of 30 normal controls. Group 2 included 30 patients with known organic visual loss. Group 3 contained 35 patients with suspected nonorganic monocular visual loss. Participants were asked to describe what they saw while viewing a single Snellen letter when a 4-prism diopter base-down prism was placed in front of their better eye. Outcome was measured by whether the participant sees one or two letters with the prism in place. RESULTS: Vision-appropriate results were given by all members of Group 1 (two images) and by all members of Group 2 (one image). Two images were seen by 31 of 35 members of Group 3, indicating nonorganic visual loss. The other 4 subjects in Group 3 saw one image; each was subsequently found to have occult pathology. CONCLUSION: The vertical prism test quickly differentiates organic from nonorganic monocular visual acuity loss.

Medical Subject Headings

Adolescent; Adult; Aged; Humans; Malingering (diagnosis); Middle Aged; Prospective Studies; Single-Blind Method; Vision Disorders (diagnosis); Vision Tests (methods); Visual Acuity

Publication Date

1-1-2004

Publication Title

American journal of ophthalmology

ISSN

0002-9394

Volume

137

Issue

1

First Page

135

Last Page

7

PubMed ID

14700656

Digital Object Identifier (DOI)

10.1016/s0002-9394(03)00865-1

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