Evidence of an Adaptive Cytoskeletal System Associated With Laser Induced in vivo Photoreceptor Injury

Abstract

Abstract: : Purpose: Utilization of the high numerical aperture of the checkered garter snake (Thamnophis m. Marcianus) for in vivo observation of laser induced photoreceptor damage and active repair mechanism identification with anti–actin antibody. Methods: Anesthesia was induced with ketamine–xylezine, IM. Animals with previously induced laser photoreceptor damage were evaluated with anti–actin A, tagged with FITC (Fluorescein Iso Thio Cyanate), IP. A Rodenstock confocal scanning laser ophthalmoscope (CSLO) equipped with a confocal fluorescein angiography system was employed to evaluate the intensity of the FITC tag on the photoreceptors in and adjacent to the photoreceptor lesion site. Results: Photoreceptors and circulating macrophage reflectivity increased when exposed to the anti–actin A with FITC vs. FITC alone. Visibly damaged photoreceptors failed to tag with FITC and anti–actin, while adjacent non–damaged photoreceptors and nerve fiber layer were visibly tagged within 30–60 seconds. Neither the endothelial cells of the capillaries nor the circulating RBCs, cells known to be lacking in an active cytoskeletal system, were visibly tagged with the anti–actin. The fluorescein only control showed a much slower and diffuse development of photoreceptor reflectivity and minimal macrophage reflectivity. Conclusions: While previous histological studies have shown passive photoreceptor migration into photically damaged retinal lesion sites, the present investigation demonstrates the presence of an active photoreceptor migration process associated with photoreceptor repopulation of laser induced photoreceptor damage sites.

Keywords: cytoskeleton • age-related macular degeneration • chromatic mechanisms