Abstract
In order to understand better what patients with an irreversible defect of the macular area are able to perceive, we attempted to assess capacities of a higher order than visual acuity and contrast sensitivity, such as form perception and object recognition and their evolution over time. We studied the identification of low-pass filtered images by patients with exudative age-related macular degeneration (ARMD) before laser photocoagulation as well as three weeks and three months after treatment. Images were low-pass filtered with Gaussian filters varying in bandwidth from 0.25 to 8 cycles per degree. For each image, the minimal bandwidth for identification was determined using an ascending method of limits. Identification threshold was defined as the bandwidth at which 50% of the images were recognized. The results indicate that the patients required a higher bandwidth to identify images embedded in a background. An improvement of patient performance over time was also found due to memory.