Thiazolidinediones is the name for a class of drugs used to treat Type 2 diabetes. The class incudes Actos and Avandia. A new study published in The Archives of Internal Medicine involving over 103,000 people with Type 2 diabetes who were followed for about ten years. Those using Actos or Avandia were found to have about two to three times higher risk of macular edema. Taking the drugs in combination with insulin increased the risk.
An author of the study, Iskander Idris, recommended that people taking Actos or Avandia would be wise to get their vision checked regularly, especially if they are taking insulin or have a history of vsion problems. He pointed out that his study showed that taking ACE inhibitors, which are used for hypertension, seemed to have a protective effect. Some other steps that could help reduce the risk of macular edema, he said, were lowering blood pressure and keeping glucose levels in check.
Though there was no way to know for sure why the drugs might damage the retina, it may have something to do with greater sodium and fluid retention or changes in blood vessels, Dr. Idris said.
Macular edema is swelling or thickening of the eye's macula, the part of one's 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. Thus, diabetics already at risk for macular edema face an increased risk if they are taking Actos or Avandia.
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