RESTORATION OF THE OUTER BLOOD-RETINAL BARRIER AFTER KRYPTON LASER PHOTOCOAGULATION

The restoration of the outer blood-retinal barrier following krypton l aser injury to the rat retina was studied at small and large laser les ions using intravenously injected sodium fluorescein, horseradish pero xidase, and catalase. The regenerated choriocapillaris and new blood v essels were permeable to fluorescein and peroxidase, but not to catala se. The regenerating retinal pigment epithelium gradually reformed a c ontinuous sheet of cells covering all small laser sites and the periph ery of large lesions. Zonulae occludens between the regenerated cells restored the outer retinal barrier and prevented diffusion of peroxida se into the retina. This occurred along Bruch's membrane and the new b lood vessels that were covered by the regenerated pigment epithelial c ells, but not in the center of the large lesion that was not relined b y regenerated cells.