Diabetic Retinopathy and Calcium Dobesilate.
Diabetic retinopathy is retinopathy (damage to the retina) caused by complications of diabetes mellitus, which can eventually lead to blindness. It is the most common diabetic eye disease and affects up to 80% of all patients who have had diabetes for 10 years or more. Small blood vessels - such as those in the eye - are especially vulnerable to poor blood sugar (blood glucose) control which could cause an over accumulation of glucose and/or fructose damaging the tiny blood vessels in the retina. During the initial stage, called nonproliferative diabetic retinopathy (NPDR), most people do not notice any change in their vision. In the United States, diabetic retinopathy is the leading cause of blindness in adults. All people with diabetes mellitus are at risk - those with type 1 diabetes (juvenile onset) and those with type 2 diabetes (adult onset). Between 40 to 45 percent of Americans diagnosed with diabetes have some stage of diabetic retinopathy.
Calcium dobesilate, also known as 2,5-dihydroxybenzene sulfonate, is a drug commonly used in the treatment of diabetic retinopathy and chronic venous insufficiency. The pharmacology of calcium dobesilate reveals its ability to decrease capillary permeability, as well as platelet aggregation (clumping together of platelets) and blood viscosity (a measure of the resistance of blood to flow).
A multi-center randomized, double-blind and placebo controlled study assessed the effect of calcium dobesilate on the occurrence of diabetic macular edema. The study, which took place in 40 different centers in 11 countries, enrolled 635 patients with type 2 diabetes and mild-to-moderate non-proliferative diabetic retinopathy. The patients were then randomly selected to receive either calcium dobesilate or a placebo. Clinically significant macular edema (CSME) developed in 86 of the 324 people who took calcium dobesilate and in 69 of the 311 who took the placebo. It was determined that people who took the drug were 32 percent more likely to develop CSME than those who took the placebo. This information suggests that calcium dobesilate could neither prevent the occurrence of macular edema nor reduce the probability of developing it. The researchers concluded that the best way to prevent diabetic blindness is by implementing systemic screenings for diabetic retinopathy and preventive laser treatment for those who develop macular edema or proliferative retinopathy.1
1 Haritoglou C, Gerss J, Sauerland C, et al. Effect of calcium dobesilate on occurrence of diabetic macular oedema (CALDIRET study): randomised, double-blind, placebo-controlled, multicentre trial. The Lancet. 2009;373(9672):1364-1371.