P 337 Glycoprotein deposition in vascular walls of diabetic retinopathy studied by immunohistochemistry

Puroose: Proliferative diabetic retinopathy is assumed to develop because vasogenic factors are released from retinal areas that are ischaemic and hypoxic secondary to occlusion of the retinal vascular bed. It has been propclsed that vascular occlusion in diabetic retinopethy may be due to the deposition of periodic acid Schiff positive glycoprotein compounds in the retinal vascular walls. but the role of these glycoproteins for retinal vascular occlusion has not been established. Methods; Periodic acid Schiff staining and immunohistochemistry to laminin, fibronectin, vitronectin .and type VI collagen was studied in eleven areas of capillary closure and eleven adjacent control areas from seven eyes of five diabetic patients, and in five midperipheral areas from five eyes of five age-matched controls. In each eye from diabetic patients the localized vascular lesions were identified from casts of the retinal vascular system. Beg&& In the retina from diabetic patients there was a significantly higher number of vessels showing periodic acid Schiff staining and immunoreactivity to the studied glycoproteins. However, there was no difference between the number of glycoprotein containing vessels in areas of vascular occlusion and in adjacent control areas in diabetic patients, and the material occluding the lumen centrally in areas of vascular occlusion did not show any glycoprotein staining or immunoreactivity. Conclusion% The findings confirm that glycoproteins are deposited in the vascular walls of diabetic retinopathy, but the findings also suggest that other factors are involved in causing vascular occlusion in this disease.