Nonlinear component of the electroretinogram recorded from the posterior pole of normal and highly myopic human eyes

To extract the nonlinear component of the electroretinogram (ERG) from the posterior pole (pp) of the human ocular fundus and to evaluate the possibility of its clinical application, three types of stimulus modes - doubleflash, single-flash, and delayed single-flash stimuli were produced using a conventional electrophysiological system. A large hexagonal element was presented on a CRT monitor, and ppERGs were recorded from 14 normal eyes and 16 eyes of eight highly myopic patients. The nonlinear component of the ppERG was obtained by subtracting the single-flash ERG and delayed singleflash ERG responses from the double flash ERG response. Three peaks were commonly observed in the nonlinear component of ppERG, all of which were significantly depressed in patients with high myopia. ppERGs that can be obtained using a simple algorithm might be useful in clinical applications. Copyright (C) 2002 S. Karger AG, Basel.