Contribution of rod and cone pathways to the dark-adapted electroretinogram (ERG) b-wave following retinal degeneration in RCS rats

Although the RCS rat is widely used as a model of progressive photoreceptor loss, it is unclear how the relative rod and cone functions change with age. Rod and cone b-waves were isolated using a double flash ERG paradigm. In contrast to cones, rods never reached normal functional maturity levels, and the ERG b-wave changed from being predominantly rod-driven to being purely cone-driven by age 74 days, at which point, b-waves were progressively replaced by negative STR-like (scotopic threshold response) waves that persisted up to age 180 days. A double flash commonly abolished this wave and unveiled a b-wave.