Retinal Function and Histopathological Assessment after Intravitreal Cidofovir Injection in Normal Dogs

Abstract

This study was performed to evaluate effect of an intravitreal injection of cidofovir in beagle dogs. Nine beagle dogs (18 eyes) were used and randomly assigned to three groups of various dosage: 100, 500, and 1,000 µg. Aqueoucentesis was followed by an intravitreal injection of cidofovir. Intraocular pressure (IOP) was measured twice a week and electroretinography (ERG) and ophthalmoscopic examination were performed every week during the study. At the end of the study, all eyes were enucleated for histopathologic evaluation after euthanasia. The lowest IOP was observed 10 days after the injection in all groups. Irreversible reductions in IOP and reduced amplitudes of ERG recordings were identified in the eyes injected with higher dose groups than the 100 µg group. Histopathologic examination revealed that there were dose-related toxicities to the ciliary body and the retina. These results suggest that intravitreal cidofovir had dose-dependent IOP lowering effects associated with ciliary body destruction, but had the potential to cause retinal toxicity in beagle dogs.