Too much 'Eye Candy': The growing concern of Diabetic Retinopathy

 

Diabetic retinopathy (DR) is one of the most important complications of diabetes and is a leading cause of blindness among working adults. Better understanding of the risk factors of DR in Asians can pave the way for timely treatment and intervention of diabetic patients. 

Diabetes affects approximately one in twelve Singaporeans aged 18 to 69 years, and in those aged 60 to 69 years, this figure is even higher at 32.4%. This situation is likely to worsen over time, compounded by factors such as dietary and lifestyle changes.

Diabetic retinopathy (DR) is one of the most important complications of diabetes and is a leading cause of blindness among working adults. For example, in Singapore, among Malays with diabetes, the overall prevalence figures of any DR was found to be around 35.0%, whereas the corresponding figures for the severe stages of DR such as macular edema and vision-threatening DR were around 5.7% and 9.0%, respectively.

This represents a significant percentage of our population with important consequences from a potentially preventable complication of diabetes.

Understanding Diabetic Retinopathy

DR is usually asymptomatic and may only be detected by the patient when the retinal changes have progressed to an advanced stage, where treatment is often complicated or impossible. Studies have shown that almost all patients with Type 1 diabetes and over 60% of patients with Type 2 diabetes develop DR after 20 years. Therefore, the duration of diabetes appears to be one of the most important correlates of DR. Aside from vision-threatening complications of DR, studies have also found associations of DR with stroke, nephropathy and heart disease.

Current treatment for DR relies on widespread laser therapy to the retina that leaves behind destructive scars. Newer therapeutic agents that require repeated injections into the eye are costly and carry an increasing risk of adverse outcomes with each treatment.

Detecting diabetic Retinopathy

DR will be considered present if any characteristic lesion as defined by the Early Treatment Diabetic Retinopathy Study (ETDRS) severity scale is present: microaneurysms (MA), hemorrhages, cotton wool spots, intraretinal microvascular abnormalities (IRMA), hard exudates (HE), venous beading and new vessels.

Macular edema is defined by hard exudates in the presence of MA and blot hemorrhage within one disc diameter from the foveal centre or presence of focal photocoagulation scars in the macular area. Clinically significant macular edema (CSME) is considered present when the macular edema involved is within 500mm of the foveal centre or if focal photocoagulation scars are present in the macular area.

DR is categorised as minimal non-proliferative DR, mild non-proliferative DR, moderate non-proliferative DR, severe non-proliferative DR and proliferative retinopathy. Vision-threatening retinopathy is defined as the presence of severe non-proliferative DR, proliferative retinopathy or CSME. The following series of illustrations describe the various stages of DR.* 

Better understanding of the risk factors for DR in Asians may enable the development of population and ethnicity specific prevention and intervention programme, which may decrease the morbidity and cost associated with this disease.