Cortical OFF-potentials from the S-cone pathway reveal neural damage in early glaucoma.

We used background adaptation and silent substitution techniques to record full-field ON and OFF-visually evoked cortical potentials (VECPs) selectively from the S-cone and L- and M-cone pathways in 15 patients with primary open angle glaucoma (POAG), and 15 normal controls. The most statistically significant (P=0.01) VECP test for POAG was a voltage change in the S-cone pathway cortical OFF-response. A sensitivity of 93% was achieved, with 60% specificity at minimum error rate. This is presumed to reflect reduced activity in the S-cone and magnocellular visual pathways, and may provide an effective method for research and monitoring change in early glaucoma.