Temporary vitreous gas tamponade by perfluoromethylcyclopentane

Using perfluoromethylcyclopentane (FMCP; US patent no. 5,441,989, granted 1995) we have developed a new vitreous gas tamponade in a rabbit model that allows complete filling of the vitreous cavity without vitrectomy and without a significant increase in intraocular pressure. In humans this procedure would allow the blockage of inferior and posterior retinal holes without special positioning of the patient. Perfluoromethylcyclopentane (FMCP), a liquid perfluorocarbon with a boiling point slightly above body temperature, is injected in minute volumes into the vitreous cavity, where it vaporizes, thereby filling a gas volume approximately 500 times its liquid volume. FMCP was injected into the midvitreous in six rabbits (six eyes). After 2-3 days a complete gas tamponade was achieved in three eyes. Two eyes showed 75-90% filling, and one eye was filled only 50% with gas. Intraocular pressure was highest in the completely filled eyes, ranging from 26.6 to 38.8 mmHg. In all eyes the maximum expansion of the gas bubble lasted 2 weeks. One eye developed a retinal detachment. All eyes showed transient subcapsular cataracts. The results of this study showed that intravitreal injection of FMCP, a new perfluorocarbon liquid, results in a complete gas tamponade of the vitreous cavity which lasts 2 weeks without severe intraocular pressure rise and without vitrectomy. This procedure will be especially useful for eyes that have retinal detachment from inferior or posterior retinal holes. Injection of a conventional gas such as SF6 or C3F8 usually does not block retinal holes in inferior or posterior locations without tedious positioning and risk of (transient) glaucoma. Since the mechanism of transition of FMCP from liquid to gas in the vitreous is poorly understood, we are currently studying FMCP vaporization in an in vitro eye model.