[Temporal integration in diseased eyes. I. Exposure duration in visual acuity testing]

Critical duration in visual acuity testing can be viewed as an expression of temporal integration in the human visual system. We examined this phenomenon in 13 eyes with central serous retinopathy (CSR) and 6 eyes with macular edema, by measuring visual acuity at several limited exposure times. The results were then compared with those for 17 normal eyes. The acuity target was a single Landolt ring projected upon a small square screen. The size, direction, and exposure time of the target were computer controlled. The mean critical durations of the CSR and macular edema groups were 1.78 sec. and 2.69 sec. respectively. These values were significantly (p less than 0.01) longer than the mean critical duration of the normal control group (0.62 sec.). Although the mechanism behind the longer critical duration in diseased eyes remains poorly understood, we believe this method provides a possible approach to the study of diseased visual conditions.