Electrophysiological assessment of visual deficit in glaucoma

Steady-state visual evoked potentials (VEP(S)) in response to contrast reversed vertical grating patterns and uniformly flickering fields were recorded in patients with glaucoma and in controls. In steady-state VEP(S), responses to temporal and spatial aspects of visual stimuli are combined, which makes the assessment of visual function dependent on their interaction. Fourier analysis of pattern reversal VEP waveforms showed marked deficits in temporal processing of spatial contrast for glaucoma patients. The degree of glaucomatous damage, as manifested by greater optic nerve atrophy and visual field loss, was correlated with progressive disruption of the VEP waveform and progressive failure in temporal processing of spatial contrast patterns. The VEP(S) in response to uniform full-field flicker showed no deficit.