HISTOPATHOLOGY OF DIABETIC-RETINOPATHY IN MAN

The retinal changes associated with diabetes mellitus are a consequenc e of the systemic microangiopathy with modifications related to the in traocular environment. The vascular disorders underlying background re tinopathy are arteriolar hyalinosis (which together with abnormalities in the circulating blood can give rise to focal capillary closure), v enular dilatation, and capillaropathy in the form of pericyte degenera tion, basement membrane thickening and microaneurysm formation. Retina l complications consist of plasma exudation and punctate haemorrhages. Maculopathy is due to cystoid oedema. Increasing closure of capillari es is linked with cotton-wool spots and intraretinal microvascular ano malies, the former reflecting a consequence and the latter a response to increased ischaemia. Vascular proliferation in front of the retina originates from venules close to areas of ischaemia; the endothelium m ay be fenestrated initially and fibrosis may accompany the new vessels .