OCT may be a valuable tool for the assessment and monitoring of anterior optic pathway dysfunction in children with demyelinating diseases.

Lipid hydroperoxides (LHP) at high concentrations are cytotoxic, but at sublethal concentration, they induce synthesis of cytokine vascular growth factors. Intracorneal injections of 30 μg LHP placed 5 mm from the superior limbus stimulated early vasodilation of limbal vasculature and a rapidly developing, sustained neovascularization. Under these conditions, vessels grew at the rate of 0.3 mm/day to a total length of 7.5 mm, 25 days after injection. Cholesterol peroxides were less effective. Developing vessels were oriented towards the stimulus. Around the developing vessel there was dissolution of the stromal extracellular matrix. The most distal endothelial cells displayed prominent endoplasmic reticulum, a lack of basement membrane or tight junction complexes and leakage of fluorescein dye. Both the injection site and superior quadrant showed increased levels of tumor necrosis factor (TNF)-alpha and vascular endothelial growth factor after exposure to LHP. The neovascular response was inhibited by simultaneous administration of TNF-alpha antibody or pentoxifylline, an inhibitor of TNF-alpha synthesis. This corneal model of peroxide-induced neovascularization should prove useful for temporal studies of events in the initiation and propagation of signals leading to neovascularization, and for evaluating effects of treatment on neovascular growth.

To test the hypothesis that oxidative damage associated with tissue hypoxia plays a role in neovascularization, a lipid hydroperoxide (LHP) was injected into the vitreous of rabbits. Single injections of LHP (50-600 microg) caused a sustained retinal neovascularization visualized clinically by ophthalmoscopy and confirmed by microscopy. Vasodilators, i.e. histamine and nitric oxide, peaked at 6h and 7 days, respectively. The levels of both tumor necrosis factor-alpha and interleukin-1alpha peaked at 12h and dropped to basal levels by 24h. Expression of vascular endothelial growth factor (VEGF) and transforming growth factor-beta peaked at 24h and were sustained throughout the following 3 weeks, and platelet-derived growth factor was also elevated throughout the same period. Upregulation of these five angiogenic cytokines, but not basic fibroblast growth factor, occurred prior to the appearance of neovascularization. Leakage of fluorescein at the tips of new vessels was demonstrated by fluorescein angiography. Linoleic hydroperoxide induced neovascularization, but saturated or unsaturated native C-18 fatty acids had no effect. The cascade of multiple, angiogenic cytokines induced by LHP may interact to promote sustained neovascularization.

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