Fluorangiographic study of the ocular fundus in normal horses

Abstract

Purpose: To describe the protocol and appearance of fluorescein angiography (FA) in normal horses. Animals: A total of 25 healthy horses aged between 5 and 15 years. Materials and Methods: The horses were sedated with 15 μg/kg detomidine and 50 μg/kg butorphanol and dilated with topical tropicamide 1%. All angiograms were recorded after intravenous bolus injection of 10 mg/kg of fluorescein sodium solution. Results: Two successive angiographic phases could be discerned: the choriopapillary phase, starting at 46.95 ± 9.48 s, and the retinal vascular phase, starting at 47.79 ± 10.38 s. The retinal vascular phase was divided in three parts: filling phase, maximum fluorescence point, and fading phase. During the filling phase, the dye progressed into the retinal vessels, obtaining maximum fluorescence at 59.79 ± 10.39 s, termed the maximum fluorescence point. The fading phase started immediately following the maximum fluorescence point. During this phase, vascular fluorescence decreased to complete reduction at 74.76 ± 9.81 s. Also, areas of delayed choroidal filling, the presence of short retinal vessels in the ventral region of the optic disc, and a particular filling of the optic disc were also observed. Conclusions: The normal angiographic sequence was described in horses. FA may be a useful method for studying the integrity of the blood-retinal barriers in horses. © 2008 American College of Veterinary Ophthalmologists.