Color Contrast Perimetry: Hue Discrimination Defects in Acquired Dyschromatopsias

Abstract

Color contrast perimetry was used to study the central visual field defects of patients with acquired dyschromatopsias resulting from diseases of the macula or optic nerve. Patients were classified according to the apparent axis of their hue discrimination defect: (1) predominantly red/green; (2) predominantly blue/yellow; (3) global hue discrimination deficit. A computer controlled color video tangent screen was used to examine the central visual field of all patients. Comparisons were made to automated threshold static perimetry. Patients with hue discrimination defects predominantly in a blue/yellow axis were also found to have relative preservation of both luminance and color contrast sensitivity at the fovea. Conversely, those patients that had hue discrimination defects predominantly in a red/green axis were found to have central visual field defects for both luminance and color contrast that failed to preserve foveal function. It is proposed that the apparent hue discrimination defects in acquired dyschromatopsias are principally the result of the heterogenous spatial distribution of central visual field defects and the physiologic heterogeneity of color opponent mechanisms in the foveal and parafoveal visual field. This would further suggest that hue discrimination defects are usually not produced by selective impairment of opponent red/green or blue/yellow channels in the afferent visual system.KeywordsVisual Field DefectColor ContrastLuminance ContrastCentral ScotomaCentral Visual FieldThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.