The Morphological Changes of Muller Cell after Argon Laser Photocoagulation in Pigmented Rabbit

ABSTRACT

PURPOSE: Blood vessels within the retina are surrounded by Muller cells, and it is known that Muller cells may be related with the pathogenesis of diabetic retinopathy based on this histologic structure. Argon laser photocoagulation is routinely performed in the treatment of diabetic retinopathy by inhibiting neovascularization and edema, but its mechanism remains unclear. Muller cell changes were demonstrated utilizing carbonic anhydrase immunohistochemical staining to know a relation between argon laser photocoagulation and the effect of Muller cells in the rabbit retina. METHODS: Author used 16 rabbit retinas which were obtained from 8 rabbits. Exposure time and spot size were kept 0.15 second and 500 microgram. 150~350 mW of power intensity was needed to produce moderate degree coagulation in rabbit retina. RESULTS: We observed retina and its histological changes at 1 week, 2 weeks, 3 weeks and 4 weeks after photocoagulation by using carbonic anhydrase staining. The differences in the morphological changes in Muller cells and retina layers were observed between moderate and severe degree coagulation. With severe degree coagulation, the loss of all the retinal layers was observed. On the other hand, with moderate degree coagulation, proliferated pigment epithelial cells and chorioretinal adhesion were observed with loss of photoreceptor and outer nuclear layer. Muller cells were observed by carbonic anhydrase staining with proliferated Muller cells with increased nuclei and proliferated process. CONCLUSIONS: These findings suggest that Muller cells might be important in the scar formation by argon laser photocoagulation and that the proliferaration of Muller cells play a certain role in the therapeutic mechanism.