Figure Ground Discrimination in Age-related Macular Degeneration
Résumé
Purpose: To investigate impairment in discriminating a figure from its background, and to study its relation with visual acuity and lesion size in patients with neovascular age-related macular degeneration (AMD). Methods: Seventeen patients, with neovascular AMD and a visual acuity of less than 20/50 were included. Seventeen age-matched healthy subjects participated as controls. Complete ophthalmologic examination was performed on all participants. The stimuli were photographs of scenes containing animals (targets) or other objects (distractors), displayed on a computer monitor screen. Performance was compared in four background conditions: the target in the natural scene; the target isolated on a white background; and the target separated by a white space from either a structured scene or a non-structured shapeless background. Target discriminability (d') was recorded Results: Performance was lower for patients than for controls. For the patients, it was easier to detect the target when separated from its background (under isolated, structured and nonstructured conditions) than it was when located in a scene. The performance of patients was improved with increasing exposure time, but remained lower in controls. Correlations were found between visual acuity, lesion size and sensitivity for patients. Conclusions: Figure/ground segregation is impaired in patients with AMD. A white space surrounding the object is sufficient to improve its detection and to facilitate figure/ground segregation. The results may have practical applications to the rehabilitation of the environment in patients with AMD.