Panretinal laser photocoagulation failed to retard degeneration in rhodopsin P347L transgentc pigs
Purpose Various tines of evidence suggest that injury to the eye, or to the retina, may retard retina! degeneration in animal models, probably by causing retinal cells to release factors that may promote cell survival. In the RCS rat, preservation of retinal function by laser treatment has been reported. Therefore, laser photocoagulation may be of potential benefit in the treatment of retinal degenerations, such as retinitis pigmentosa (RP). Transgenic pigs expressing the rhodopsin P347L mutation manifest rod-cone degeneration similar to human RP We used this animal model to study the effect of panretinal photocoagulation for retinal degeneration. Methods. We used the portable IRIS Medical OcuLight SLx diode laser, with the indirect ophthalmoscopic delivery system, to create retinal laser burns in 33 four-week old transgenic pigs One eye was treated in a panretinal pattern; the fellow eye served as a control We delivered 280 to 400 spots, approximately 500-800 io.m in size, and spaced approximately one burn width apart, in a panretinal scatter pattern, sparing the central, cone rich, area centralis. Three weeks after treatment, and then at one-week intervals, the extent of degeneration was judged by light microscopy of retinal sections Results The ophthalmoscopic appearance of the 3-week post-surgery laser scars appeared virtually identical to panretinal laser scars observed in humans. Up to 12 weeks post-surgery, we observed no significant difference between the treated and untreated retinas Both degenerated with a similar time course as the retinas of untreated transgenic pigs. Conclusion The particular laser treatment regimes used in these studies failed to retard retinal degeneration in rhodopsin P347L transgenic pigs.
Wong, F; McCuen, BW; Hao, Y
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