Pneumatic retinopexy by evaporation of fluorocarbon liquids: in vitro and in vivo results

To develop an expanding gas tamponade allowing a controlled and complete filling of the vitreous cavity in the non-vitrectomized eye.Twenty-two different liquid fluorocarbon mixtures with a high vapour pressure were tested in an in vitro eye model and in rabbit eyes. The intraocular pressure (IOP), the anterior segment of the eye, the vitreous and the retina were inspected at each examination during a period of 2 weeks. The timepoint of maximal gas expansion and the period required for complete absorption of the gas bubble were recorded.In vitro, admixtures of perfluorocarbons (PFCLs) and of semifluorinated alkanes (SFAs) with ether/alkanes generated limited temporary gas expansion but increased IOP. Admixtures of n-pentane in paraffin oil or silicone oil resulted in incomplete gas filling remaining for several days, with moderate IOP. In vivo, different clinical features and gas expansion were observed after the injection of PFCLs saturated with CO(2) or SF(6). Normal IOP was noted, but only with a transient and incomplete gas expansion and tamponade. For example, with n-pentane/n-hexane/perfluoromethylcyclopentane/perfluoromethyl-cyclohexane (1:1:1:1) a very rapid gas expansion was observed, followed by a raised IOP, a shallow anterior chamber, and finally rupture of the globe. The correlation between the in vitro and in vivo data was low.Gas endotamponade based on evaporation of liquid fluorocarbons is possible, but a complete and reliable tamponade could not be achieved. The best results were demonstrated by admixtures with an overall density1.00 g/cm(3), an inert carrier with high vapour pressure, and a highly volatile substance. Further detailed investigation into the factors influencing evaporation is required.