“…11 The amplitude of the response to a 30-Hz flicker, measured in microvolts, was compared from visit to visit. ERG readings were grouped according to 6 categories: none (0.0 mV), poor (0.2-25 mV), fair (25.1-50.0 mV), good (50.1-75.0 mV), very good (75.1-100 mV), and excellent (Ͼ100 mV).…”