The pathogenesis of diabetic retinopathy

Diabetic retinopathy remains a major cause of loss of vision. The Diabetes Control and Complications Trial (DCCT) has implicated hyperglycaemia as a probable major direct causative factor in the pathogenesis of diabetic retinopathy. There are several plausible mechanisms by which high glucose concentrations could lead to the functional and later structural changes characterising diabetic retinopathy. These include increased activity of the aldose reductase pathway, increase de novo synthesis of diacylglycerol from glucose, causing protein kinase C activation, increased non-enzymatic glycation and increased oxidative damage. The demonstration of the potential roles of these pathways and the subsequent effects of growth factors in enhancing angiogenesis provide potential new approaches to the prevention and treatment of diabetic retinopathy.