The effect of induced diabetes on the electroretinogram components of the pigmented rat

The fast and slow components of the electroretinogram (ERG) of the pigmented rat were observed 2, 4, and 19 weeks after the induction of diabetes by streptozotocin. The diabetic state was confirmed by measures of serum and urine glucose and the appearance of polydipsia and polyuria. There was no apparent effect on the b-wave of the ERG in the diabetic animals at the 2- and 4-week periods of observation; however, at 19 weeks the form of the intensity-amplitude curve differed from that of the controls. The c-wave of the ERG was significantly reduced in amplitude at the 2-week period of observation, and a progressive reduction occurred throughout the remaining periods of observation. The relationship between the observed reduction in amplitude of the c-wave and the reported pathological changes in the pigment epithelium in diabetic animals is discussed.