Alterations in blood elements in the pathogenesis of diabetic retinopathy.

The role of altered blood elements in the pathogenesis of retinal ischemia and diabetic retinopathy and the relationship to abnormal carbohydrate metabolism and to elevated levels of growth hormone are discussed. These changes involve red blood cells, platelets, plasma proteins, fibrinolytic response, and vascular endothelium. The significance of blood elements mediated by plasma is noted with aggregation of normal red cells when cross-matched with diabetic plasma and with intensive plasmapheresis, which caused red cell disaggregation and improvement of retinopathy. The relationship of metabolic control to diabetic retinopathy is reviewed and is evident by improvement of retinopathy occurring eight weeks after continuous subcutaneous infusion of insulin. A hypothesis is presented which integrates the multifactorial processes involved in the pathogenesis of diabetic retinopathy. Only through future research can one prove the implicated mechanisms in the pathogenesis of diabetic retinopathy and the role of strict metabolic control in altering the progression of retinopathy.