It is one of the major complications of diabetes. There are several stages of diabetic retinopathy. Many people may not notice a change in their vision for years. Most investigations so far have focused on the blood vessels of the eye, because these can be observed readily in humans. However, our tests in animal models indicate that cells away from blood vessels begin to change in less than three months.
Normal vision requires all the cells in the retina to work together properly.
Lieth's group found that diabetes injures the glial cells so that they do not properly metabolize glutamate. Glutamate is a neurotransmitter used in the communication between neurons of the retina, and too much glutamate can cause neurons to die. Lieth and his colleagues found that glutamate accumulates in the retinas of experimental animals within three months after the onset of diabetes. In related findings, the Penn State Retina Research Group will soon publish findings that retinal neurons in diabetic animals die within the first months of diabetes. The electrical activity in the retina changes within a few years after people become diabetic.