Pattern ERGs and visual evoked potentials in maculopathies and optic nerve diseases.

Normative data were obtained in 52 volunteers to both transient and steady-state checkerboard pattern reversal. Two sizes of checks subtending 15' and 31' of visual angle were used. The simultaneous recording of pattern ERGs (P-ERGs) and visual evoked potentials (VEPs) permitted the determination of the retinocortical time. That is, the transit time expressed in milliseconds between the activation of retinal structures and the arrival of the signal in the visual cortex. Three groups of patients with maculopathies, optic atrophy, and suspected optic nerve demyelination were also studied. Early maculopathies were characterized by delayed P-ERG b-waves and delayed VEPs but normal retinocortical time. Optic nerve demyelination was characterized by normal P-ERGs, delayed VEPs, and prolonged retinocortical time. Optic atrophy and established maculopathies were characterized by abnormal P-ERGs and VEPs. The implications of these findings were discussed.