Diabetic Retinopathy

Diabetic retinopathy is damage to the retina that results from diabetes mellitus.

Diabetic retinopathy is one of the most common causes of blindness in older people in developed countries. Diabetic retinopathy is most common in people with a history of poorly controlled blood sugar levels. The risk is especially high in those people who have had diabetes for many years, high blood pressure, and high blood cholesterol levels.

Causes

Diabetic retinopathy occurs when blood vessels in the retina are damaged over time by high levels of sugar in the blood. At first, high blood sugar levels cause the blood vessels to leak blood and fluid into the retina. Eventually, the blood vessels close, depriving the retina of nutrients and oxygen. This fosters the growth of new blood vessels. The appearance of these vessels indicates the beginning of a phase of proliferative retinopathy, which can lead to blindness through bleeding, retinal detachment, or glaucoma.

Symptoms and Diagnosis

People with diabetic retinopathy may have no symptoms despite extensive growth of new blood vessels. Some people experience gradual vision loss. Others develop blind spots scattered about in their field of vision. More serious symptoms include "floaters" or "flashing lights" due to retinal tears and detachments or abrupt vision loss when newer, weaker blood vessels burst and bleed into the eye.

An eye doctor can diagnose diabetic retinopathy by examining the retina through a dilated pupil. If blood vessels are leaking, the central part of the retina may become swollen (macular edema). Fluorescein angiography may be performed, in which a dye is injected into an arm vein and the retina is photographed.

Treatment

Treatment usually involves using light energy from a laser to seal abnormal blood vessels and decrease leakage. This procedure is called laser photocoagulation. Laser photocoagulation is also used to inhibit new blood vessel growth. Periodic treatments over years may be necessary. Laser photocoagulation prevents further vision loss but rarely improves vision. Vision may improve, however, after surgery is performed to clear blood from the vitreous gel of the eye (vitrectomy) or after repair of retinal detachments.

Prevention

Strictly controlling blood sugar levels, blood pressure, and blood cholesterol levels helps prevent diabetic retinopathy. In addition, an eye doctor should examine the eyes at least annually, because people with diabetes may develop retinopathy without knowing it.