Microvascular access to the uveal tract in the rabbit eye for ocular pharmacologic studies

Drug delivery to the eyes is quite inefficient regardless if the drugs are administered topically or intravenously. It is known that less than 1% of topically instilled drug can be absorbed into the eyes while even less of intravenously injected drugs reach the eyes. A research model has been developed in this study which allows delivery of drugs effectively to uveal and anterior structures of the eye. This experimental model allows drugs to be delivered to the eye via cannulation of and retrograde flow through the valveless vortex veins. In addition, the superficial branch of the vortex vein (draining the ciliary body and iris) or the deep branch (draining the choroid plexus of the retina) can be selectively cannulated to suit the researcher's needs. Finally, this procedure minimizes systemic drug actions which otherwise would complicate interpretation of experimental results. This model can be used for in vivo laboratory studies on (a) metabolic and physiological processes of the uveal tract in the eye, and (b) drug delivery to selective tissues of the uveal tract in the eye. Dose-response relationships of pilocarpine and timolol to lower intraocular pressure were demonstrated with this model.