Retinal vascular calibre as a predictor of incidence and progression of diabetic retinopathy.

Recent advances in retinal photographic imaging techniques have allowed objective and precise measurement of subtle vascular characteristics in the retina, including the retinal vessel calibre (diameter). Data from population-based and clinic-based studies show that changes in retinal calibre are associated with systemic vascular risk factors and might reflect early microcirculatory alterations in people with diabetes prior to the onset of clinically significant complications, such as diabetic retinopathy. Prospective studies suggest that in people with type 1 diabetes, wider retinal venules are associated with progression of mild to more severe levels of retinopathy, including proliferative retinopathy. Thus, studying retinal vascular calibre changes might offer the potential to improve our understanding of the early pathophysiological pathways of diabetic retinopathy, potentially allowing the development of novel therapies. Future research is still needed to assess the ability of retinal vessel calibre measures to provide clinically useful prognostic information that might add to risk prediction of diabetic retinopathy over and above the contribution from traditional risk factors, including glycaemic levels and the duration of diabetes.