Modulation of the renin-angiotensin system and retinopathy.

Pathology The earliest detectable lesions of diabetic retinopathy are microaneurysms. These are associated with excessive vascular permeability and result in exudate formation. There is occlusion of the vessels and stimulation of growth factors, which in turn promote the proliferation of new blood vessels and the growth of fibrous tissue. This may contract and lead to haemorrhage. The process of angiogenesis, however, occurs right through the evolution of diabetic retinopathy.