Functional Constriction of the Ocular Motor Field: Description and Preliminary Evaluation of a New Technique to Help Distinguish Organic From Nonorganic Visual Field Loss

Abstract

To describe and evaluate a novel clinical method to assess patients with constricted fields using the Goldmann perimeter, with the aim of distinguishing nonorganic from organic field constriction. Ten patients with constricted visual fields who were undergoing kinetic perimetry as part of their routine workup were included. Five of them had suspected functional visual loss (FVL), and 5 had organic field loss. Patients were assessed on the Goldmann perimeter using a test that combines kinetic perimetry (visual field) with a modified uniocular field of fixation (motor field). The main outcome measure was the size of the visual and motor fields. In all patients with organic visual loss, the motor field was expanded relative to the visual field, as would be expected (P = 0.02). In all patients with suspected FVL, the motor field was markedly constricted and was not significantly different from the visual field (P = 0.27). The motor fields of the 2 groups were significantly different sizes (P = 0.001). Patients with FVL may exhibit functional behavior on a motor task, believing that it is a test of vision. Functional constriction of the ocular motor field may help distinguish organic from nonorganic visual field loss, but further evaluation is required.