Vitreous adenosine levels in a porcine model of retinal ischemia

Purpose: The factors responsible for ocular neovascularization (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 26 male domestic pig eyes following an intravenous injection of rose bengal (10 mg/kg). Clinical examinations and aqueous and vitreous taps were performed serially over 28 days. Aqueous and vitreous adenosine levels were measured by HPLC and fluorometry. Results: Vitreous adenosine concentration was 145.73 ± 72.23 nM prior to laser. Concentration progressively increased to 1057.21 ± 678.88 nM on day 14 and 2371.32 ± 1366 nM on day 28. Aqueous adenosine levels were consistently lower at all time points and remained close to baseline throughout the course of the study. Conclusions: Adenosine appears to be released from ischemic retina into the vitreous in this model of photodynamic laser venous thrombosis. The vitreous concentration of adenosine increases with the duration of ischemia.