Non-invasive measurement of oxygen saturation in retinal vessels of patients with diabetic retinopathy
08 / 2000 - 08 / 2004
Diabetic retinopathy is in its nonproliferative stage characterized by edema and microvascular abnormalities. The hallmark of the proliferative stage is neovascularization. The importance of oxygen in the progression of diabetic retinopathy is indicated by animal studies and the positive effects of laser treatment in humans. This therapy improves the oxygen supply to the inner retina by destruction of photoreceptors in the outer layers. Hypoxia induces among others the production of vascular endothelial growth factor (VEGF), which causes vascular leakage and neovascularization. The aim of this project is to investigate the alleged role of oxygen. To this purpose we will test and validate our newly developed multiwavelength retinal oximeter to measure noninvasively oxygen saturation in retinal vessels, especially veins. The findings will be related to the various disease stages and to vitreous or aqueous VEGF levels as obtained intraoperatively during vitrectomy or cataract surgery. In addition, we will evaluate the influence of laser therapy. As a corollary we will also investigate the possibility to detect with the apparatus derangements in autoregulation, since this may be an early indicator of vascular dysfunction due to hyperglycemia.