Transcorneal oxygenation of the preretinal vitreous
C. A. Wilson, J. D. Benner, B. A. Berkowitz, C. B. Chapman and R. M. Peshock
Department of Ophthalmology, University of Texas Southwestern Medical Center at Dallas.
OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
