Intravitreal anti-vascular endothelial growth factor (VEGF) pharmacotherapy, introduced in 2004,1 has evolved over the last decade to revolutionize the treatment of patients suffering from subretinal choroidal neovascularization (CNV). Anti-VEGF agents, which are readily available today, are much better, more potent, and longer acting in comparison with previous treatment modalities, and therefore have dramatically improved the prognosis of patients with CNV.
Patients losing vision secondary to CNV, such as patients suffering from exudative age-related macular degeneration (AMD), can now expect stabilization and even improvement of their visual acuity, as opposed to the slow and certain visual deterioration that was the rule before the anti-VEGF era.2–6
Vascular Endothelial Growth Factor
VEGF is a diffusible cytokine that promotes angiogenesis and increases vascular permeability. It is a product of a gene family that plays an important role in normal development and angiogenesis.7 The influence of VEGF in retinal diseases is profound. This dimeric glycoprotein of approximately 40 kDa is upregulated in response to hypoxia. It plays a pivotal role in stimulating abnormal growth of pathological new blood vessels in the adult retina and choroid. VEGF is also a potent inducer of vascular permeability and leakage that can lead to retinal edema and thickening.8,9
There is mounting evidence that increased VEGF expression is associated with pathologic CNV.7 CNV, a form of abnormal blood vessel growth which emerges from choroidal vessels, penetrates Bruch’s membrane and grows below the retinal pigment epithelium (RPE) space and into the subretinal space.10 Figure 1 shows the different stages of growth of a subretinal choroidal membrane in response to VEGF stimulation. The increased production of VEGF and subsequent CNV formation can occur in degenerative, inflammatory, neoplastic, traumatic, hereditary, and idiopathic diseases of the retina and choroid. The most commonly encountered conditions associated with CNV are AMD and pathologic myopia. AMD is the leading cause of irreversible vision loss among the elderly population in the Western world.11
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