Does hypertension play a role in diabetic retinopathy?

ABSTRACT

Diabetic retinopathy is a common complication of diabetes. It represents one of the frequent causes of visual disability among diabetic subjects during the period of active life. The risk factors for diabetic retinopathy are poor glycemic control, hypertension, duration of diabetes, hyperlipidemia and proteinuria. It has been observed that prevalence of hypertension is higher in diabetic subjects than in the general population and as it also plays a major role in the progression of diabetic retinopathy, so tight control of hypertension is mandatory. The possible mechanisms by which hypertension affects diabetic retinopathy are haemodynamic (impaired autoregulation and hyperperfusion) and secondly through VEGF (Vascular Endothelial Growth Factor), as it has been observed that hypertension independent of hyperglycaemia upregulates the VEGF expression in retinal endothelial cells and ocular fluids. The level of control of blood pressure are debatable but nearer the blood pressure to the normal levels, better the chances of preventing the onset and progression of diabetic retinopathy. The lowering of blood pressure to a normal range is more important than the type of antihypertensive medication used. Diabetic retinopathy is one of the important causes of visual disability in diabetic subjects during the period of active life. It is characterized by gradually progressive alterations in the retinal microvasculature, leading to increased vasopermeability, areas of retinal occlusion and retinal neovascularization. The complications associated with increased vasopermeability and uncontrolled neovascularization can result in severe and permanent visual loss.