A Screening Method for Chiasmal Visual-Field Defects

Abstract

A strategy that selectively explores the vertical fixational meridian of the visual field was as sensitive as conventional quantitative Goldmann perimetry in detecting chiasmal hemianopic field defects, although it required only one quarter of the usual testing time. A trained but "masked" perimetrist, applying this abbreviated method to the examination of 28 eyes with hemianopic defects, 17 eyes with nerve-fiber defects, and 14 normal eyes, detected 100% of the hemianopias when using the Goldmann perimeter, 92% when using the conventional tangent screen, and 87% when using the projection tangent screen. False-positive diagnoses of hemianopic defects were 16%, 11%, and 14% on the respective instruments. While this strategy did not define the field defects fully, it accurately identified the features of diagnostic importance. By its efficiency, this approach may encourage greater use of visual fields as a determinant in managing the conditions of patients with unexplained visual loss.