Abstract
Purpose::
To study the feasibility of oxygenation of the vitreous as a therapeutic modality for the treatment of retinal occlusive diseases specifically Branch retinal Vein Occlusions. (BRVO)
Methods::
Normal Pigmented rabbits were given baseline evaluation via Stratus OCT, Fluorescein angiogram (FA), and fundus photos, as well as vitreous sampling for ELISA analysis for VEGF, 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. All rabbits were followed at 2 days and 6 days post occlusion with repetition of the baseline exams. Rabbits in the oxygenation group had their vitreous cavity perfused with a 95% O2, 5% CO2 mixture via a 25-gauge cannula for one hour at each follow up.
Results::
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 6 of follow up. STRATUS OCT documented a significant increase in the thickness of the myelin wings at both follow up exams in both control (373 µm baseline/ 506 µm at day 6 follow up) and oxygenation groups (398 µm at baseline/ 431 µm at day 6 follow up). VEGF analysis showed a significant increase in vitreous VEGF levels by day 6 in both groups but less so in the oxygenation group. (oxygenation group baseline VEGF: 1005 pg/ml, day 6: 1813 pg/ml, control group baseline: 694 pg/ml, day 6: 3006 pg/ml)
Conclusions::
Intermittent oxygenation of the vitreous cavity in this rabbit photothrombotic BRVO model led to reduced levels of VEGF within the vitreous, as well as a reduction of the edema within the myelin wings. Although suggestive of a therapeutic effect, establishment of vitreous oxygenation as a therapeutic modality in retinal vein occlusions will require more long-term models and further refinement of the oxygenation technique.
Keywords: retina • vitreous • vascular occlusion/vascular occlusive disease