Longevity of expanding gases in vitrectomized eyes

The effect of lensectomy and vitrectomy on the disappearance of intraocular gas was studied in a rabbit model. Ten rabbits underwent lensectomy and vitrectomy in one eye, and ten others underwent vitrectomy alone in one eye. The second eye of each rabbit served as a control. Equal amounts of perfluorocarbon gas, either perfluoromethane (CF4) or perfluoromethane (C2F6), was injected into both eyes of the 20 animals. After an interval corresponding to one or more half-lives of the gases had elapsed, the residual volumes of gas in the paired eyes were measured directly by an invasive method and compared. The volume of gas in the aphakic vitrectomized eye was 1.3 times greater, on average, than in the paired control eye. There was no significant difference between eyes that had undergone only vitrectomy and the control eyes. It is postulated that vascular congestion and decreased aqueous secretion caused by surgical trauma were responsible for the delay in the disappearance of gas in the eyes that underwent both lensectomy and vitrectomy.