The lesions which may be present in diabetic retinopathy are diverse, and the research, both clinical and histopathological, which has been necessary to elucidate their formation and evolution, has had to be laborious and prolonged. These studies have, however, led to the use of some well-defined therapeutic measures which are undoubtedly of value in this condition which is now the leading cause of blindness in patients under 65 years of age in Great Britain (Sorsby, I973). A patient with diabetic retinopathy may lose vision in one of two conditions which often co-exist: (i) Because of bleeding from new vessel formations or later from vitreous opacities and secondary traction effects on the retina (Proliferative diabetic retinopathy). or (2) Retinal oedema, deposition of lipoid, pre-retinal fibrosis, or capillary closure in the macular area (Simple or exudative diabetic retinopathy or, better, diabetic maculopathy).
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