Cideciyan and colleagues Samuel G. Jacobson, MD, PhD, the F.M. Kirby Professor in Penn's Department of Ophthalmology and Director of the Center for Hereditary Retinal Degenerations at Scheie, Gustavo D. Aguirre, VMD, PhD, Professor of Medical Genetics and Ophthalmology at Penn's School of Veterinary Medicine, and Gregory M. Acland, BVSc, of Cornell University asked whether modest light levels cause damage to retinas of the rhodopsin mutant dogs. The investigators performed the routine clinical procedure of retinal photography in the dogs. Normal dogs had no ill effects of the procedure. Surprisingly, the mutant dogs had complete degeneration one month after retinal photography and only in those regions that were photographed. There were no abnormalities associated with neighboring regions of the retina that were not photographed. Further experiments with focal light exposures and cross-sectional retinal imaging showed that retinal injury was detectable within 30 minutes and could cause complete retinal degeneration within a month following these moderate lights.
"Rhodopsin mutant dogs are one of several naturally occurring canine retinal degenerations which duplicate human hereditary eye diseases," comment Aguirre and Acland, who have spent more than 20 years identifying and investigating inherited veterinary retinal degenerations and their treatments. "Identifying a light-induced component to the natural history of retinal degeneration in the rhodopsin mutant dogs means that now we can test new treatments for value and safety before attempting the same in human patients."
When the investigators used lower light exposure levels, the degeneration process was slower and lasted six months or longer. Even further lowering of light exposure resulted in reti
Contact: Olivia Fermano
University of Pennsylvania School of Medicine