Visual thresholds measured with red test object on backgrounds of high and low luminance

Visual thresholds measured at the central and midperipheral visual field have been tested in the eyes of a series of 10 healthy normal persons using a monochromatic red test light object (Goldmann area III, 25' of arc in the visual field) of 632 nm wavelength presented on white backgrounds of 150 cd/m2 (5000 K) and 1 cd/m2 (2800 K) luminance, as well as with no background illumination following a 45 min period of dark-adaptation. Another series of 10 normal subjects were tested with an equally large white (2800 K) test object shown on a white background of 1 cd/m2 (2800 K) luminance. Results obtained in congenital and acquired achromatopsia as well as in three relatively mild cases of rod-cone dystrophy have been related to the normal thresholds.