The risk for developing blood vessel damage in the eyes is a complication of having diabetes. When this happens, the problem may be classified as a type of diabetic retinopathy. Diabetic Macular Edema (DME) is a type of diabetic retinopathy. DME occurs when tiny blood vessels in the retina swell and leak fluid into the middle of the macula. The macula is filled with nerve cells responsible for sensing light, and when fluid accumulates the ability of those cells to discern light is hindered.
There are two types of diabetic macular edema.
Inside the eye
The macula is seen as a yellow spot in the center of the retina on diagnostic pictures of the inside of the eye. The macula is responsible for producing sharp central vision. Central vision is the middle of your visual field. A healthy retina and macula are important for complex eye/brain tasks, such as facial recognition.
DME impairs eyesight
To illustrate, let's say the person with DME sits in front of the TV watching a program. Unfortunately, the middle of the TV screen is blurry, and may appear so distorted that it is difficult or impossible to understand what is happening. Although the middle of the picture is blurry, the area around the middle—the peripheral field of vision, is good.
DME is painless and often, there are no warning signs that the problem is developing. Diabetic macular edema can affect one or both eyes, and symptoms vary from mild to severe. To protect your eye sight, call your doctor if you experience:
Melmed S, Polonsky KS, Larsen PR, Kronenberg HM. Complications of diabetes mellitus. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Elsevier Saunders;2011.
National Eye Institute, National Institutes of Health. Facts about diabetic retinopathy. http://www.nei.nih.gov/health/diabetic/retinopathy.asp. Accessed April 16, 2013.