RESPONSES TO CHROMATIC AND LUMINANCE CONTRAST IN GLAUCOMA - A PSYCHOPHYSICAL AND ELECTROPHYSIOLOGICAL STUDY

Increasing anatomical evidence indicates that large retinal ganglion c ells (M-cells) are preferentially damaged in primary open angle glauco ma (GAG), while the smaller ganglion cells (P-cells) are relatively sp ared. In 13 patients with defined OAG and modest visual field defects, we evaluated the responses to stimuli that are expected to involve pr imarily the function of the P-pathway and compared them with those of control subjects. The psychophysical contrast sensitivity (CS), the PE RG and the VEPs were measured for red-green gratings of pure chromatic contrast, as well as yellow-black gratings of pure luminance contrast . As compared with controls, OAG patients had reduced CS for both lumi nance and chromatic contrast stimuli by about 6 dB. PERGs and VEPs to luminance stimuli were little affected, whereas those to chromatic sti muli were both reduced in amplitude and delayed. These results indicat e that visual dysfunction in glaucoma is not selective for the M-pathw ay, and that responses to equiluminant colour-contrast stimuli may bee f diagnostic value. (C) 1997 Published by Elsevier Science Ltd.