What is the importance of retinal hypoxia?
The retinal vasculature is relatively sparse in order to minimise optical interference in the light path. This results in a large oxygen tension difference between retinal arteries and veins which can easily be compromised if damage occurs to the vascular bed. Capillary nonperfusion, loss of retinal capillaries, AGEs and/or oxidative stress can lead to progressive retinal hypoxia.139,140,141,142,143 Acute hypoxia rapidly activates retinal vascular endothelial cells to release inflammatory cytokines.144 These inflammatory mediators are able to recruit and promote the activation and adherence of leukocytes,145 which contribute to the obstruction of retinal capillaries, leading to further hypoxia. Chronic hypoxia is, at least in the retina, sufficient to induce the expression of angiogenic growth factors,146,147 resulting in the characteristic retinal neovascularization associated with proliferative diabetic retinopathy (PDR). The observation that retinal neovascularization occurs adjacen
