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T. M. O'Hearn, H. Ameri, A. Shariati, M. Humayun; Oxygenation of the Anterior Vitreous in a Rabbit Photothrombotic Model of Retinal Vein Occlusion. Invest. Ophthalmol. Vis. Sci. 2008;49(13):6116. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To study the feasibility of oxygenation of the anterior vitreous using direct injection of oxygen into the vitreous as a therapeutic modality for the treatment of retinal occlusive diseases specifically Branch retinal Vein Occlusions (BRVO) in rabbit
Normal Pigmented rabbits were given baseline evaluation via Stratus OCT, Fluorescein angiogram (FA), and fundus photos, prior to intravenous injection of Rose Bengal dye (40mg/kg) followed by photothrombotic occlusion of retinal veins using an Argon laser. Following occlusions rabbits were split into a control group and a group to receive vitreous oxygenation. Intravitreal oxygen recordings were performed at baseline and at each follow up. All rabbits were followed at 3 days and 7 days post occlusion with repetition of the baseline exams. Rabbits in the oxygenation group had oxygen injected into the vitreous at a rate of 6µL O2/min for one hour on day 3, a rate estimated to be equivalent to the total retinal oxygen consumption.
Fundus photos and FA confirmed creation of venous occlusions in all animals. Fluorescein angiograms showed some evidence of limited venous recannulation in all animals at day 7 of follow up. STRATUS OCT in all rabbits documented a significant increase in the thickness of the myelin wings at day 3 follow up (252 µm baseline; 326 µm at day 3, p=0.04) Intra-ocular oxygen recordings in all rabbits documented significant reduction of vitreous oxygen levels pre-retinally from baseline to day 3 follow up (20.4mmHg O2 baseline; 1.9mmHg O2 at day 3, p= 0.006) In oxygenation rabbits, injection of oxygen into the anterior vitreous at the rate of 6µL O2/min was able to significantly raise pre-retinal oxygen levels. (5.2mmHg O2 prior to oxygenation, 39.0 mmHg post oxygenation) Histological analysis of retina harvested at day 14 after occlusion found minimal TUNEL positivity in both control and oxygenation groups, and equivalent amounts of upregulation of GFAP in both groups as well.
Intermittent oxygenation of the vitreous cavity at a rate equivalent to total retinal oxygen consumption in this rabbit photothrombotic BRVO model was able to restore pre-retinal oxygen levels to supranormal levels. Histological analysis via TUNEL staining did not reveal any increased apoptosis in oxygenated animals.
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