Retinitis pigmentosa (RP) is an inherited eye disease that causes visual disability leading to blindness. Over the last 15 years, researchers have pinpointed defects in dozens of genes causing different forms of RP. Surprisingly, patients with the same genetic defect can show different severities of vision loss and rates of disease progression. This effect is most dramatic across the retina of some individuals where regions with normal vision can abut regions of no vision. Environmental factors have been near the top of the suspect list for this variation in severity. An environmental factor experienced by all, but to varying extents, is exposure to light – bright lights have been previously speculated to accelerate certain forms of RP.Now, investigators from the University of Pennsylvania and Cornell University provide evidence for retinal injury caused by moderate light exposure in dogs with a mutation in the rhodopsin gene. Since the blindness in these dogs mimics that observed in human RP caused by mutations in the rhodopsin gene, the investigators strongly recommend limiting excess light exposure in these patients.
