Photopic ON- and OFF- Responses in Korean Normal Subjects

ABSTRACT

PURPOSE: To explore the effects of stimulus duration, stimulus intensity, and background luminance on the amplitude and waveform of the ON- and OFF- responses of photopic ERG and to provide standard parameters of ON- and OFF- responses for normal Korean populations. METHODS: Twenty normal subjects (20 eyes) were enrolled to record photopic ON-and OFF-responses using a contact lens electrode with built-in LEDs and an LED-driver. The influence of stimulus duration on wave amplitudes was studied at flash durations that varied from 5 to 200 ms. The influence of stimulus intensity was studied with 0.4, 0.7, 1.1, 1.4, 1.7, 1.9, 2.0, and 2.1 log cd/m2. In addition, the influence of background luminance was studied with 20, 30, 40, and 50 cd/m2. RESULTS: Among 20 normal subjects, the d-waves in 16 subjects were isolated from b-waves with more than 50 ms of stimulus duration. The d-wave was observed for a 30-ms stimulus duration in 3 subjects and for a 100-ms duration in 1 subject. The amplitudes of the b-and d-waves increased as stimulus intensity was increased. The amplitudes of b-and d-waves decreased as background luminance was increased. CONCLUSIONS: Our results suggest that the clinical use of ON-and OFF-response recording can be obtained with stimulus parameters from 100 to 150 ms in duration and a 1.7-2.1 log cd/m2 intensity under 30-40 cd/m2 background luminance.