Transcorneal Oxygenation of the Preretinal Vitreous

Abstract

Transcorneal oxygenation is a promising approach to the treatment of various anterior ocular diseases, but its effect on the vitreous and retina is uncertain. The purpose of this study was to evaluate the ocular conditions necessary to permit transcorneal oxygenation of the preretinal vitreous in the rabbit eye. Oxygen at atmospheric pressure was supplied via a goggle to the eye while preretinal oxygen tensions were measured with a minimally invasive technique: fluorine-19 (19F) nuclear magnetic resonance spectroscopy of a small preretinal droplet of perfluorotributylamine. Experiments were performed on lensectomized eyes with intact posterior lens capsules (group 1) or in eyes that had also undergone posterior capsular discission (group 2) and mechanical vitrectomy (group 3). To better understand the results of the oxygenation studies, a water-soluble, freely diffusible contrast agent was applied topically to the cornea, and its penetration into the aqueous and vitreous was studied using T1-weighted magnetic resonance imaging. Preretinal PO2 was significantly increased after 30 minutes of transcorneal oxygenation in group 3 eyes (P = .002). In contrast, no change was observed in the other groups despite 30 minutes (group 1) or 3 hours (group 2) of oxygen exposure. The imaging studies demonstrated that contrast penetration of the vitreous was uniform and rapid in eyes in group 3, consistent with a fluid flow-dominated process. A much slower process of anterior and midvitreous enhancement was observed in groups 1 and 2 that was consistent with contrast diffusion. Because of bulk fluid movement, transcorneal oxygenation of the retina is feasible in single-compartment (vitrectomized, lensectomized) eyes within a reasonable period (30 minutes). This finding could prove useful in the treatment of retinal diseases in which hypoxia may play a role.