Do Intraocular Angiotensin II Levels, Plasma Prothrombotic Factors and Endothelial Dysfunction Contribute to Proliferative Diabetic Retinopathy?

Purpose: To investigate whether diabetic retinopathy (DR) is associated with abnormalities in: (i) aqueous humour Angiotensin I (Ang I) and Angiotensin II (Ang II) levels; and (ii) plasma Ang I, soluble P-selectin, lipoprotein (a) (Lp(a)), endothelial markers and haemorheological abnormalities.

Methods: Cross-sectional study of diabetic patients and healthy controls undergoing cataract surgery.

Results: 21 diabetic patients (12 males; mean age 67.0 years) were studied. Plasma levels of Ang II were lower in diabetics compared with controls (p<0.05). There were no differences in mean aqueous Ang I and Ang II levels in diabetics with or without proliferative DR compared with controls. Mean systolic blood pressure was higher in Group 1 patients (p=0.02). Patients with DR also demonstrated high Lp (a) and abnormal haemorheological factors (fibrinogen, white cell count).

Conclusion: Ang I and Ang II do not significantly contribute to the pathogenesis of DR. Patients with DR also had abnormal Lp (a) and haemorheological factors. The role of hypertension in the pathogenesis of DR needs further evaluation.