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Anterior segment changes in rabbits after experimental aqueous replacement with various amounts of different
Background:
We evaluated biomicroscopic and histological effects on the anterior segment in the rabbit eye after temporary aqueous substitution with various amounts (0.2 cc and 0.025 cc) of perfluorodecaline (PFD) and perfluorophenanthrene (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 each for periods of 1, 2, or 4 weeks. At these points some eyes were enucleated for histological examination. After 2 and 4 weeks the substances were removed 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 weeks. Four eyes received balanced salt solution and served as controls. Beside biomicroscopic evaluation and measurement of the intraocular pressure, endothelial cell counts and corneal pachymetry were performed regularly during follow-up.
Results:
The postoperative results were well comparable for PFD and PFP eyes. Within the first 2 weeks postoperatively corneal edema with endothelial cell loss was observed in both groups. Thereafter regression of the edema started independently of whether the substances were removed or not. IOP was not elevated at any time. At the end of follow-up central corneal thickness was the same as initially. In the inferior corneal endothelium cell density decreased to 45-50% of that in normals. Histologically, vacuoles in the iris and chamber angle were found inferiorly after 4 weeks. Chamber angle closures were present between 5 and 7 o'clock in those eyes where the PFC liquids had been removed after 2 and 4 weeks. Eyes with 0.025 cc PFD or PFP droplets showed vacuolization of the inferior trabecular meshwork 8 weeks postoperatively that was comparable with eyes which had a 50% aqueous replacement for 4 weeks. Control eyes remained unchanged in all aspects.
Conclusion:
Anterior segment damage caused by PFC liquids is a contact-dependent 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.