Anterior segment changes in rabbits after experimental aqueous replacementwith various amounts of different perfluorocarbon liquids

Background: We evaluated biomicroscopic and histological effects on the ant erior segment in the rabbit eye after temporary aqueous substitution with v arious amounts (0.2 cc and 0.025 cc) of perfluorodecaline (PFD) and perfluo rophenanthrene (PFP). Methods: A quantity of 0.2 cc of the two perfluorocarbon (PFC) liquids was exchanged simultaneously with about 50% of the aqueous in 15 rabbit eyes ea ch for periods of 1, 2, or 4 weeks. At these points some eyes were enucleat ed for histological examination. After 2 and 4 weeks the substances were re moved from the remaining eyes, which were then followed up for 8-10 weeks. In an additional 8 eyes, 0.025 cc PFD or PFP was injected and left for 8 we eks. Four eyes received balanced salt solution and served as controls. Besi de biomicroscopic evaluation and measurement of the intraocular pressure, e ndothelial cell counts and corneal pachymetry were performed regularly duri ng follow-up. Results: The postoperative results were well comparable for PFD and PFP eye s. Within the first 2 weeks postoperatively corneal edema with endothelial cell loss was observed in both groups. Thereafter regression of the edema s tarted independently of whether the substances were removed or not. IOP was not elevated at any time. At the end of follow-up central corneal thicknes s was the same as initially. In the inferior corneal endothelium cell densi ty decreased to 45-50% of that in normals. Histologically, vacuoles in the iris and chamber angle were found inferiorly after 4 weeks. Chamber angle c losures were present between 5 and 7 o'clock in those eyes where the PFC li quids had been removed after 2 and 4 weeks. Eyes with 0.025 cc PFD or PFP d roplets showed vacuolization of the inferior trabecular meshwork 8 weeks po stoperatively that was comparable with eyes which had a 50% aqueous replace ment for 4 weeks. Control eyes remained unchanged in all aspects. Conclusion: Anterior segment damage caused by PFC liquids is a contact-depe ndent effect seen in the early observation period. Experimentally there was no difference between the products used or between 2 and 4 weeks' duration of the tamponade.