Spatial contrast transfer functions of the pattern-evoked electroretinogram.

Pattern ERGs in response to pattern-reversal stimuli varying in spatial frequency (range: 0.2-9.03 cycles/deg) and contrast (range: 0.03-0.93) were recorded from two normal male subjects. At most spatial frequencies the response amplitude increased linearly up to the highest contrast without saturation. From the amplitude-versus-contrast plots spatial contrast-transfer functions were derived for different levels of contrast. The sensitivity of the reversal response showed a spatial selectivity around 4 cycles/deg, which was more pronounced at low, rather than at high, contrast values. Good agreement with the psychophysical contrast-sensitivity curve was found. The procedure described permits a quantitative analysis of the sensitivity of the retina to spatial contrast stimuli and could be helpful in the diagnosis of diseases of the eye and the optic nerve.