Diabetic retinopathy is an eye disease that damages the blood vessels in the retina. The retina is a light-sensitive group of nerves at the back of the eye that interprets visual images and sends them to the brain. Diabetic retinopathy is the leading cause of new cases of blindness among working-age Americans, according to the American Diabetes Association.

Diabetic retinopathy begins as nonproliferative retinopathy. In this stage, high glucose (blood sugar) levels weaken the blood vessels in the retina. Initially, these vessels may develop balloon-like pouches called microaneurysms and leak fluid, causing swelling in the retina. At this stage, few patients experience symptoms.

Over time with poorly controlled glucose, the disorder can progress to a stage known as proliferative retinopathy. This occurs when the retina does not receive enough blood, and new, abnormal blood vessels grow on its surface. These weak vessels cannot carry the blood the starved retina needs. They frequently hemorrhage (bleed), resulting in retinal scarring, retinal death and detachment, conditions that can cause partial or total loss of vision.

The longer a person has diabetes, the higher the risk of developing diabetic retinopathy. After 20 years, it will affect up to 90 percent of patients with type 1 diabetes and up to 60 percent of those with type 2 diabetes, according to the U.S. Centers for Disease Control and Prevention. Scientists have recently learned that diabetic retinopathy can even affect people with prediabetes.

Diabetic retinopathy is most treatable when diagnosed early. Possible treatments include laser therapy (photocoagulation) and a surgical procedure called vitrectomy.

People with retinopathy often do not experience symptoms until it has progressed to the proliferative stage. For this reason, it is crucial that patients with diabetes schedule regular eye exams so that an ophthalmologist can detect, diagnose and treat the disorder before it affects vision. Even with treatment, retinopathy may continue to worsen. However, individuals can reduce their risk of diabetic retinopathy through measures such as control of glucose and cholesterol, and scientists are working on innovations including drug treatments.