**1. Introduction**

The adult retina is a neural tissue with high metabolism and the highest oxygen consumption per unit weight of all human tissues. Therefore, the choroid, the most vascular layer of the eye also nourishing the retina, has one of the highest blood-flow rates in the body, 800 – 1000 mL/100 g tissue/min [1]. In healthy adults this delicate ocular vascular system is maintained and controlled by the balance between the angiogenic factors and angiogenic inhibitors [2].

Age-related macular degeneration (AMD) is the result of complex interactions between lipo‐ fuscinogenesis, drusenogenesis, and inflammation which can lead to choroidal neovasculari‐ zation(CNV)[3]. An imbalance between the proangiogenic vascular endothelial growth factor (VEGF) and the antiangiogenic pigment epithelium-derived factor (PEDF)[3-4], plays a major role in the pathogenesis of the disease.

Inhibitors of VEGF represent a relatively new treatment for CNV. These agents include the Macugen (aptamer) which was almost completely abandoned with the introduction of the efficient FDA approved Ranibizumab (Lucentis; Genentech, Inc, South San Francisco, CA), in addition to others such as the Bevacizumab (Avastin; Genentech, Inc), and the new FDA approved drug Eylea(VEGF Trap Eye Regeneron, Tarrytown, NY, USA).
