Swelling of the central part of the retina of the eye, which can cause blurred vision. Macular edema is just one facet of diabetic retinopathy, or retinal disease.
The retina is a thin, transparent membrane in the back of the eye that translates light into nerve impulses that travel along the optic nerve to the brain. The macula is an oval, yellow spot at the center of the retina; it is involved in central vision and provides much of a person’s fine visual acuity, which is necessary for reading. The macula is also an important part of color vision.
In people with diabetes, for reasons that aren’t completely understood, the small blood vessels in the retina can become abnormal and leaky. Fluid then collects within the retina, causing it to swell. When swelling occurs in the macula, a person experiences blurred central vision.
Keeping blood glucose levels as close to normal as possible can reduce the risk of diabetic retinopathy, including macular edema. If macular edema does develop, it can be treated with photocoagulation, or laser surgery. Laser treatment closes off leaking blood vessels, thus reducing the swelling.
Diabetic retinopathy can be treated very successfully if caught early. For this reason, the American Diabetes Association recommends that people with Type 1 diabetes have an annual comprehensive eye exam starting within 3–5 years after diagnosis. For people with Type 2 diabetes, annual exams should begin soon after diagnosis. If results of eye exams are normal, the doctor may consider testing less frequently (once every 2–3 years).