The value of assessing progressive loss of red/green and yellow/blue chromatic sensitivity in glaucoma

Abstract

*Correspondence: franziska.rauscher@medizin.uni-leipzig.deThe value of assessing progressive loss of red/green and yellow/blue chromatic sensitivity in glaucoma.The study employed visual stimuli designed to isolate and reveal how spatial, temporal and chromatic aspects of visual processing change from normal sensitivity to extreme loss in glaucoma. The experiments carried out examined the fovea and each of four paracentral retinal regions, arranged diagonally away from fixation at an eccentricity of 6°. Spatial vision was investigated by measuring both absolute detection thresholds and functional contrast sensitivity using Landolt ring stimuli (Ophthalmic Physiol Opt 2022;42:1363–1378). These psychophysical tests based on Landolt C optotypes measure both detection thresholds and gap orientation discrimination thresholds in the same experiments using randomly interleaved test locations. First‐order motion perception was examined by using moving stimuli embedded in static luminance contrast noise. Red/green (RG) and yellow/blue (YB) colour thresholds were measured with the Colour Assessment and Diagnosis (CAD) test, which makes use of random, dynamic luminance contrast noise (±45%) to isolate the use of RG and YB colour signals. Subjects were normal controls (n = 65) and glaucoma patients with binocular visual field defects (n = 15) classified based on their Humphrey Field Analyser mean deviation (MD) scores. The impairment of visual function varied depending on the stimulus attribute and location tested. The severity of loss increased monotonically with disease progression. For subjects with mild glaucoma (MD −0.01 to −6.00 dB), significantly more data points exceeded the upper normal threshold limits for the corresponding age for RG colour thresholds than for any other visual test (Br Med Bull 2017;122:51–77), followed by motion thresholds. This was particularly the case for the parafoveal locations when compared with the equivalent thresholds measured at the fovea. The results suggest that a multifaceted measure of binocular visual performance based on foveal and parafoveal tests of RG colour vision and first‐order motion, can best inform on the progression of glaucoma and the overall loss of visual performance for comparison with other measures of changes in the quality of life in patients with glaucoma.Keywords: Glaucoma, Visual function, Colour vision, Motion detection, Contrast, Acuity, Colour Assessment and Diagnosis, CAD.