Recording multifocal electroretinograms with fundus monitoring

Purpose. To record multifocal electroretinograms (ERGs) with simultaneous fundus monitoring. Methods. An infrared television fundus camera was used to monitor the fundus. A tightly packed array of 19 yellow light-emitting diodes (LEDs) was used as the stimulus source and LEDs were alternated between on and off according to a binary m-sequence at a rate of 75 Hz. The stimulus array subtended approximately 25°of the visual angle. Multifocal ERGs were recorded with a Burian-Allen bipolar contact lens electrode from two normal subjects and three patients with macular disease. Results. When the center of the stimulus was positioned on the fovea, the amplitude of the response was largest at the fovea and decreased toward the peripheral retina; the response pattern corresponded to the spatial distribution of cone cells. When the center of the stimulus was positioned on the optic disc, the response at the optic disc was undetectable. Reliable multifocal ERGs were obtained with fundus monitoring fiom patients with macular disease. Conclusions. This system made it possible to monitor the stimulus on tKe fundus and to adjust the stimulus to the correct retinal locations with exact tocusing. Our findings indicate that this method provides reliable results and may be especially useful in patients with poor fixation. In addition, our results suggest that the stray light effect in the multifocal stimulus system is minimal, if any.