Simultaneous electroretinograms and visually evoked potentials from adult amblyopes in response to a pattern stimulus

Electroretinograms (ERGs) and visually evoked potentials (VEPs) were recorded simultaneously from each eye of three adult amblyopes. A spatially alternating checkerboard pattern stimulus of constant mean luminance was used to eliminate the effect of stray light on the ERG. The VEP was affected in the amblyopic eye of all subjects. In two subjects the VEP amplitude was reduced; in the third subject the amplitude was not attenuated, but the waveform of the VEP was markedly altered. Photopic ERGs recorded from the normal and amblyopic eye of each subject with an unpatterned flashing light were equal in amplitude. However, ERGs elicited by a patterned stimulus were affected in the amblyopic eye of all three subjects; the after-potential showed larger reductions in amplitude than the b-wave. These results suggest there may be some retinal involvement in human amblyopia.