[Ocular microangiopathy in humans]

Because of the relations between retinal endothelial cells and the nervous tissue, microangiopathy is considered to be the result of combined impairments of the choriocapillaris, the pigmented epithelium, the nervous layers, the pericytes and the vitreoretinal interface. The known effects of hyperglycaemia are: the accumulation of sorbitol, the reduction of myoinositol, the lower activity of ATPase NA/K, the accumulation of AGE. The functional and structural changes are: impaired autoregulation of the blood flow, breakdown of the blood retinal barrier, thickening of the basement membrane, loss of pericytes and proliferation of endothelial and glial cells. Capillary closure is the first step in proliferating retinopathy via VEGF secreted from all the retinal cells. Normalization of the glycaemia is the only medical treatment which has been proved to be effective in the initial stages of the retinopathy. In the advanced stages, laser photocoagulation and vitreo-retinal surgery have been shown to be effective. The aldose-reductase and glycosylation inhibitors are still under investigation.