Functional changes of the aging rat retina in relation to the modifications of the ERG components

the intact eye of Wistar rat was stimulated with continual periodic light signals in the range of 0,001-500 lux and from 0,01 cps. up to the fusionfrequency. Using square-wave light stimuli of the frequency range from 0,01 to 0,1 cps. and intensity diapason of 0,1-1,0 lux the scotopic electroretinogram (ERG) consists of the following waves: b, b-negative, c, d, d-positive, respectively. At the beginning of the light sensitivity range, that is near above the threshold, on one part and over a stimulus intensity of 10 lux, on the other the ERG becomes more simple and looks appr. like a direct current (DC) response. Along with aging the ERG undergoes changing. The light sensitivity of the eye proved to be decreased, especially in the short wave range of the spectrum. Thus the ERG threshold becomes increased. The DC components are less apparent. The fast elements of high amplitudes are also missing. The slope of the frontal and descending part of the wave b gets lower. The fusion-frequency is lower with old animals as well. The spontaneous physiological biopotential noise level is significantly higher and the synchronity of elements participating in generating the ERG wave is less. Additionally a considerable great slowing-down of the adaptation processes were observed. Using light signals of different wave forms, it may be established, that differentiating ability of the retina declines more rapidly as aging advances than that of its light sensitivity.