Platelet abnormalities as related to diabetic retinopathy (with special reference to platelet shape change).

Abnormalities of platelet function may be related to the pathogenesis of diabetic retinopathy. A method for the in vitro assessment of platelet shape change (PSC), as induced by ADP in calcium-deprived platelet-rich plasma, is presented. The outcome of this test is dependent on the concentrations of ADP and of the chelating agent used. Studies in electron microscopy shoed that the parameter measured is not related to the disappearance of spiny-spherical forms. The values measured for PSC were significantly increased in a group of diabetic subjects, when compared to normal controls. In particular, patients with proliferative retinopathy showed more profound alterations of the PSC. No relations were found between the PSC values and ADP induced platelet aggregation, the plasma levels of von Willebrand factor and of factor VIII-related antigen.