The assessment of evoked potential contrast thresholds using real-time retrieval.

Electrophysiologic contrast sensitivity functions (CSF) have been estimated using lock-in amplifier signal retrieval of the visually evoked response (VER). These CSFs were compared with CSFs obtained psychophysically using the same stimulus conditions. The two measures of contrast sensitivity behave similarly in response to variations of temporal and spatial frequency. The major advantage of using real-time retrieval is speed. Threshold for a single spatiotemporal condition can be estimated in as little as 20 sec, making the application of electrophysiologic contrast sensitivity testing feasible for clinical populations.