• A gas that rapidly disappears from the vitreous may be of value in the treatment of retinal detachment. Xenon, argon, helium, carbon dioxide, and nitrous oxide were injected into the eyes of animal models to measure their disappearance times. Both Ar and He behaved much like air. The rapid disappearance of Co2 and N2O caused a profound hypotension. The gas with the most promising characteristics was Xe: 88% disappeared in three hours. The gas was replaced by aqueous as rapidly as it went into solution, so that the hypotensive effect was small.