Division on Visual Impairments

DVI Quarterly Volume 58(1)

A quarterly newsletter from the Council for Exceptional Children's Division on Visual Impairments containing practitioner tips for Teachers of Students with Visual Impairments, Certified Orientation and Mobility Specialists, and other professionals.

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of vascular endothelial growth factor (VEGF). As normal retinal vascularization occurs, VEGF is present, causing a "wave of 'physiological hypoxia'" (Chen & Smith, 2007) guiding vessel growth outward from the optic nerve. VEGF follows this wave and stimulates vessel growth. When infants receive more oxygen than they would in utero, due to premature birth and exposure to room air or oxygen therapy, this wave is interrupted, halting vessel growth. In response to the ceased vessel growth and hypoxic environment created by this halt, VEGF increases and neovascularization occurs, causing abnormal vessels and scarring. It is theorized that correctly timed administering of anti-VEGF and VEGF can mimic the natural occurrence of this process in the development of the eye and prevent ROP by preventing the loss of blood vessels, therefore preventing the response - proliferation of abnormal vessels (Chen & Smith, 2007). The use of bevacizumab, an anti-VEGF molecule, has only been used in animal models thus far. The timing of the use of anti-VEGF and VEGF is absolutely critical, contrary to each other, and has not been perfected (Agarwal, Azad, Chandra, Chawla, Deorari, & Paul, 2012). This research seems quite promising to me, as it attempts to mimic the natural development of the eye vessels, preventing ROP rather than ameliorating the problem after it occurs. Also noted in the Chen article is that insulin-like growth factor (GH/IGF-1) triggers the production of VEGF and increases as the gestational age of the newborn increases. IGF-1 is also correlated to brain development and lower levels of this hormone may not only cause lower levels of VEGF and interrupt eye development, but may also contribute to "abnormal neural retinal function" due to delayed brain development, further jeopardizing visual function (Chen & Smith, 2007). 43

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