Electrophysiological estimation of the function of different retinal zones in normal eyes and in retinal degenerations

By means of electroretinographical responses from different areas of the retina (zonular ERGs) both healthy people and patients with central and peripheral retinal degenerations were examined. Responses were registered from three retinal areas (zones): central (red, green, and blue stimuli, 10 ° in diameter, during adaptation of 20 lux); paramacular (a dim, blue, ringlike stimulus, 15 ° inner and 50 ° outer diameter, presented at the beginning of dark adaptation) and peripheral (very dim, blue ring stimulus of a 50 ° inner and 110 ° outer diameter, after 3 min of dark adaptation). The data obtained by this method of stimulation give information about the function of stimulated retinal areas and provide new criteria for the function of the spectrally different photoreceptors responsible for intact color vision. Examples are presented that reveal the value of this method for the detection of congenital color vision defects and for the classification of different types of retinal degeneration. This method is shown to be highly effective and has many advantages over the common routine Ganzfeld ERG technique, especially in cases of unusual retinal degenerations.