Diabetic Retinopathy Overview
Diabetic retinopathy is a complication of diabetes mellitus in which long-term exposure to high glucose levels in the blood has damaged retinal blood vessels. This results in new growth of abnormal blood vessels, fluid buildup in the macula (i.e., macular edema), inadequate blood supply to the retina, and possibly blood and fluid leakage into the retina and the vitreous body. Diabetic retinopathy is a leading cause of blindness in the United States. When diagnosed early in the course of the disease, diabetic retinopathy can be effectively managed.
According to John W. Kitchens, M.D., ophthalmologist and vitreoretinal surgeon in Lexington, Kentucky, in our sister publication Diabetes Focus Spring 2013, people with diabetes should get a retina exam once a year. Elevated blood glucose can damage the blood vessels in the eyes, resulting in diabetic macular edema (DME)the leading cause of vision loss in patients with diabetes. In addition to tightly controlling your blood sugar, visit an opthalmologist or retina specialist annually.
Stages of Diabetic Retinopathy
Diabetic retinopathy develops in two stages: nonproliferative and proliferative. Not all patients with nonproliferative retinopathy advance to the proliferative stage, but the more severe the condition, the more likely it will become proliferative.
Nonproliferative—This is the early stage of the disease, when damaged capillaries break and leak. Fluid buildup in the macula (called macula edema) causes blurred vision. (The macula is located in the center of the retina and is the structure that renders fine, detailed vision.)
Proliferative—During this later stage, abnormal, fragile blood vessels grow in the retina and into the vitreous body (clear gel-like substance that fills the chamber between the lens and the retina). This process is called neovascularization. These fragile vessels are prone to rupturing and bleeding into the vitreous body, causing blurred vision and possibly temporary blindness. If scar tissue forms, it may pull the retina away from the back of the eye (called retinal detachment), which can result in permanent vision loss. Macular edema also can occur during this stage.
Incidence and Prevalence of Diabetic Retinopathy
Diabetic retinopathy occurs in about 2550 percent of people with diabetes in the United States and is a leading cause of blindness.
Risk Factors for Diabetic Retinopathy
People with either type of diabetes mellitus, but especially type 1, are at risk for retinopathy. When type 1 diabetes coexists with hypertension, a person may be 4 times as likely to develop proliferative retinopathy. The duration of diabetes and the degree of hyperglycemia and hypertension also affect the risk for diabetic retinopathy.
Diabetic Retinopathy Signs and Symptoms
In its earliest stages, diabetic retinopathy usually does not produce symptoms. Once macular edema develops, vision blurs. The quality of vision may fluctuate (alternately worsen or improve slightly).
Bleeding can also cause vision loss, as the disease advances. As bleeding and leakage increase, vision decreases. In severe cases, vision is so impaired that the patient is only able to distinguish light from dark in the affected eye.