Ocular neovascularization
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REVIEW
Ocular neovascularization Peter A. Campochiaro
Received: 20 December 2012 / Revised: 22 December 2012 / Accepted: 2 January 2013 / Published online: 18 January 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Retinal and choroidal vascular diseases constitute the most common causes of moderate and severe vision loss in developed countries. They can be divided into retinal vascular diseases, in which there is leakage and/or neovascularization (NV) from retinal vessels, and subretinal NV, in which new vessels grow into the normally avascular outer retina and subretinal space. The first category of diseases includes diabetic retinopathy, retinal vein occlusions, and retinopathy of prematurity, and the second category includes neovascular agerelated macular degeneration (AMD), ocular histoplasmosis, pathologic myopia, and other related diseases. Retinal hypoxia is a key feature of the first category of diseases resulting in elevated levels of hypoxia-inducible factor-1 (HIF-1) which stimulates expression of vascular endothelial growth factor (VEGF), platelet-derived growth factor-B (PDGF-B), placental growth factor, stromal-derived growth factor-1 and their receptors, as well as other hypoxia-regulated gene products such as angiopoietin-2. Although hypoxia has not been demonstrated as part of the second category of diseases, HIF-1 is elevated and thus the same group of hypoxia-regulated gene products plays a role. Clinical trials have shown that VEGF antagonists provide major benefits for patients with subretinal NV due to AMD and even greater benefits are seen by combining antagonists of VEGF and PDGF-B. It is likely that addition of antagonists of other agents listed above will be tested in the future. Other appealing strategies are to directly target HIF-1 or to use gene transfer to express endogenous or engineered anti-angiogenic proteins. While substantial progress has been made, the future looks even brighter for patients with retinal and choroidal vascular diseases. P. A. Campochiaro (*) Departments of Ophthalmology and Neuroscience, Johns Hopkins University School of Medicine, Maumenee 719, 600 N. Wolfe Street, Baltimore 21287-9277 MD, USA e-mail: [email protected]
Keywords Angiogenesis . Age-related macular degeneration . Diabetic retinopathy . Hypoxia-inducible factor-1 . Vascular endothelial growth factor . Platelet-derived growth factor
Introduction The retina is supplied by both the retinal and choroidal vasculature The retina consists of a series of neurons that transduce images into neuronal signals that are processed and sent to the visual cortex for decoding. The photoreceptors which capture light and initiate neural transmission are located at the back edge of the retina so that light must travel through all the other layers before it is captured (Fig. 1a, b). Blood vessels absorb light and cast a shadow which would cause blank spots in images if the vessels were located immediately in front of photoreceptors. Therefore, the outer retina is avascular and retinal vessels supply only the i
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