[Effect of intravitreal gas on the destruction of anionic sites in the outer blood-retinal barrier]

The present work was undertaken to evaluate the effect of sulfur hexafluoride (SF6) injected intravitreously in rabbit eyes. The alterations of the outer blood retinal barrier that was composed of anionic sites, using a cationic probe, polyethyleneimine (PEI). We injected 0.5 ml of 100% SF6 or 0.5 ml of air into the vitreous cavity of rabbit eyes, and the 0.5% PEI-saline solution was given intravenously at 2, 4, 7, or 14 days after the injection. Control eyes demonstrated numerous PEI-positive sites at the basement membrane of the RPE, collagen fiber of Bruch's membrane, and basement membrane of choriocapillaries. Until seven days after SF6 injection, PEI-positive sites decreased, but had increased at 14 days to control levels, while in air-injected eyes, they had recovered at seven days. SF6 in the vitreous was absorbed in seven days and air in three days. While gas was present in the vitreous, the charge barrier of the outer retina and choroid decreased, but when the gas was absorbed, the charge barrier recovered. The result showed that the decrease of charge barrier was a reversible change.