Abstract
Abstract: :
Purpose: To establish normative ranges of electroretinogram (ERG) values for the patient population at the Illinois Eye Institute, Chicago, IL, and to study the changes in the scotopic and photopic ERG responses due to differences in race. Methods: Electroretinograms were recorded on 40 control subjects with a Nicolet Spirit system according to the International Society of Clinical Electrophysiology of Vision (ISCEV) published standards. The subjects were equally divided between African–American (n=20) and Caucasian (n=20) individuals. The implicit time and amplitude measurements of two ERGs obtained in each stimulus condition (rod response, maximal cone and rod response, isolated cone response, and 30 Hz flicker) were averaged for each subject. Normative value ranges were determined in relation to the 2.5th and the 97.5th percentiles of the test result distribution. Group comparisons were carried out with the Wilcoxon rank–sum test. Results: The mean age of the African–American group was 44.0 years (SD ± 12.5). The mean age of the Caucasian group was 45.0 years (SD ± 13.0). Although comparisons of the ERG responses showed a trend of smaller amplitudes for all parameters, with the exception of the rod response amplitude, statistically significant differences could not be demonstrated. One parameter (30 Hz flicker amplitude) showed a marginal statistically significant difference (P < 0.05) with the mean amplitude of the Caucasian group 18.42 µV larger than the mean amplitude of the African American group. No significant differences were found in the implicit time comparisons. Conclusions: Unlike previous reports indicating that individuals with darker fundus pigmentation (e.g. African–Americans) showed consistently smaller ERG amplitudes, our study demonstrated that the race of the individual was not a significant variable in the outcome of the ERG.
Keywords: electroretinography: clinical