Detection sensitivity to light offsets is abnormal in glaucomatous visual field.

The detection thresholds in the central visual fields of glaucomatous (n = 21), ocular hypertensive (n = 21) and normal (n = 13) individuals were tested with both light decrements (offsets = dark spots) on a cathode ray tube (CRT) and light increments (onsets = bright spots) on a bowl projection perimeter. Both types of stimuli were of equal surface area (Goldmann size IV = 16 mm2) and duration (200 milliseconds) on a 10 cd/m2 background intensity. Computerized threshold testing with light offsets on CRT could document the glaucomatous visual field loss with high accuracy and might indicate early glaucomatous visual field loss missed by the conventional light onset stimuli.