Effect of argon laser photocoagulation on the permeability of the blood-retinal barrier

The breakdown and repair of the blood-retinal barrier following argon laser photocoagulation were studied in pigmented rabbits by kinetic vitreous fluorophotometry using carboxyfluorescein as a tracer. The outward carboxyfluorescein transport across the blood-retinal barrier was significantly reduced in the photocoagulated eyes (p less than 0.01). This transport activity was normalized in 14 days. Ten rabbits were intraperitoneally pretreated with 0.1 M/kg probenecid, a competitive inhibitor, which was likely to decrease active transport across the outer blood-retinal barrier. In probenecid-treated animals, argon laser photocoagulation did not affect the permeability of the blood-retinal barrier. The present study suggests that some beneficial effects of photocoagulation may be attributed to replacement of diseased retinal pigment epithelium by rapid growth of new pigment epithelial cells and reestablishment of active transport across the restored barrier.