Laser Effects on Photoreceptor Degeneration in the RCS Rat

Abstract

The Royal College of Surgeons (RCS) rat has an inherited progressive photoreceptor degeneration which has been well characterised (1). The primary defect in the RCS rat seems to be a failure of the pigment epithelial cells to properly ingest and dispose of the rod photoreceptor outer segments (2). Although the prime defect is not in the photoreceptor cells the RCS rat has been used to assess procedures for improving photoreceptor survival in inherited retinal degenerations. In recent years several procedures have been found which alter the rate at which photoreceptors degenerate in the RCS rat. The most effective procedure, in terms of number of cells surviving and the period of survival, involves the sub-retinal transplantation of pigment epithelial cells from normal animals (3,4). In this case substantial numbers of photoreceptors survive into adult life maintaining apparently normal inner and outer segments as well as synaptic contact with the inner retina (4). By replacing the defective pigment cells the genetic defect was therefore essentially corrected.