Increase in vitreous adenosine levels prior to neovascularization in retinal ischemia

Purpose: The definitive factors responsible for ocular neovasculahzation (NV) have not been identified. Adenosine has been shown to be a mediator of ischemia in other tissues. We undertook to study adenosine levels in an animal model of retinal ischemia and NV. Methods: 2 of 3 major branch retinal veins were occluded with green argon laser in 30 male domestic weanling pig eyes following intravenous injection of rose bengal (70 mg/kg). Clinical examinations, fluorescein angiography and aqueous and vitreous sampling were performed serially over 56 days. Aqueous and vitreous adenosine levels were measured by HPLC and fluorometry. Results: Mean vitreous adenosine concentration was 206.27 ± 85.45 nM prior to laser. Concentration peaked at 3419.66 ± 3013.86 nM by day 21 and then gradually decreased to 67.53 ± 23.37 nM by day 56. Aqueous adenosine levels were consistently lower at most time points. Conclusions: Vitreous adenosine levels in this model appear to be high by day 4 and peak around day 21. NV in this model appears between 21 and 42 days post - retinal vein occlusion, during which time adenosine levels decrease. By day 56 levels drop to below baseline. RPB, Children's Miracle Network and CDS.