A multivariate analysis of intra vitreal injection of anti VEGF bevacizumab in the treatment of retinal and choroidal neovascularisation.

The retinal vasculature is arranged in 3 dimensional network. The central retinal artery is a direct branch of the ophthalmic artery arising from bifurcations adjacent to the optic disc to form a unique, intra retinal, end artery micro vascular system. Oxygen tension in the inner retina has been identified as a key regulator of retinal cell differentiation and micro vascular permeability, growth and survival by altering expression of VEGF. In the mature retinal micro vasculature this oxygen regulated control of capillary density is well illustrated by the appearance of a so called “capillary free zone”. Adjacent to arterial walls where oxygen tension is high and local expression of VEGF is low. Cilio retinal arteries may also contribute to the retinal circulation and these arise from posterior ciliary arteries. Branch retinal arteries lack an internal elastic lamina and anatomically speaking arterioles. A total of 34 Patients were included in this study. Age group was between 30-60 years. All the patients were examined for V/A, FFA for leakage, and OCT for macular thickness before and at 2wks, 4wks, 2, 3, and 4months after intravitreal injection. 1 out of 4 PDR patients was given repeat injection at the end of 3rd month as there was no response for single injection. Overall 70% of CNV cases (both classic & occult) responded with improvement and stabilization of V/A of upto 2 lines, where as only 50% of PDR and CRVO cases responded with 1line improvement by the end of the study. 78% of CNV cases irrespective of types and 50% of PDR cases responded with reduction of macular thickness of upto 100μ whereas both cases of CRVO cases responded with reduction of 50μ by the end of the study. Almost all the cases of CNV and CRVO responded to treatment with no leakage in angiography whereas 50% of PDR cases showed leakage till the end of the study. CONCLUSIONS Intravitreal bevacizumab (1.25 mg) treatment is well tolerated over 6 months with significant safety and efficacy. Nevertheless, this is a small interventional study, with no comparison arm to quantify the actual magnitude of benefit of this treatment modality compared with other therapies. This would have to be studied subsequently in larger studies and also needs to be compared with other VEGF inhibitiors regarding safety and efficacy