Macular edema is swelling or thickening of the eye's macula, the part of your eye responsible for detailed, central vision.
The macula is a very small area at the center of the retina—a thin layer of light-sensitive tissue that lines the back of the eye. Light rays are focused onto the retina, where they are transmitted to the brain and interpreted as the images you see. It is the macula that is responsible for your pinpoint vision, allowing you to read, sew or recognize a face.
Macular edema develops when blood vessels in the retina are leaking fluids. The macula does not function properly when it is swollen. Vision loss may be mild to severe, but in many cases, your peripheral (side) vision remains.
Macular edema is often a complication of diabetic retinopathy, and is the most common form of vision loss for people with diabetes—particularly if it is left untreated.
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