Retinal Oxygen distribution in normal and pathological cases; animal models and humans

Abstract

AbstractThe distribution of PO2 close to the vitreoretinal interface is heterogeneous, found higher near the arteriolar wall. Preretinal and transretinal PO2 profiles indicate that O2 diffusion from the arterioles affects the PO2 in the juxta‐arteriolar preretinal region. Both the preretinal and inner retinal PO2 recorded far from the vessels remain constant in all retinal areas. The oxygen tension (PO2) in the inner half of the retina remains largely unaffected by moderate changes in perfusion pressure. In addition a constant PO2 is observed during systemic PaO2 changes induced either by hyperoxia or hypoxia. However, an increase of PaCO2 (hypercapnia), as well as an intravenous injection of acetazolamide (carbonic anhydrase inhibitor) can both lead to an increase of preretinal PO2 due to retinal vessels dilatation. In the case of eyes with experimental branch retinal vein occlusion, PO2 values, within the inner retinal layers, are indicative of hypoxic conditions, whereas in adjacent unaffected retinal areas the PO2 remain normal. In diabetic patients undergoing vitrectomy, reports have shown a lowered vitreal POg in the affected retinal areas. Occlusion of the retinal circulation renders most of the inner retina anoxic.