Bringing Sight to Blind Dogs: Retinal Degeneration and Regeneration in Practice
Vision Science Group, College of Veterinary Medicine, University of Missouri, Columbia/USA
Purpose: To assess the long-term effects of subretinal rAAV.RPE65 gene transfer on functional vision in RPE65-/- dogs and to correlate clinical findings after treatment with results from ultrastructural studies.
Method: A group of 5 RPE65 null mutation dogs, all clinically blind from birth, treated with unilateral gene transfer, were studied and compared to normal visual dogs, using behavioral testing , simultaneous and bilateral full-field electroretinography (ERG). Morphological studies up to 10 months postoperatively were also performed in 4 RPE65-/- dogs that had all undergone gene transfer and compared to an RPE65-/- untreated dog.
Results: All dogs showed improvement in objective visual behavior already 4-6 week following surgery. During 3 subsequent objective testing sessions, up to 17 months post-surgery, the visual behavior improved both in dim and in bright light conditions. There was no significant difference in behavior between affected treated dogs and controls in bright light conditions, although this was not the case in dim light. ERGs showed significantly increased scotopic and photopic responses in the treated eye 3 months post-surgery. At six months this increase was somewhat reduced in the treated eye, especially for scotopic responses. There was, however, an effect also on the fellow, non-treated eye. This effect was observed most clearly in the photopic ERG resp
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