Diabetic retinopathy is a common cause of impaired vision, and even blindness, among diabetics. Damage to the retina probably begins fairly early in the development of diabetes, but symptoms usually do not become noticeable for years. Because early treatment can slow or halt the progress of retinopathy, doctors urge diabetic patients to have their eyes checked every year.

Long-term diabetics, especially those who are insulin-dependent, suffer a number of problems related to the impact that diabetes has on their circulation. In the eye, the small blood vessels in the retina (the back layer of the eye) become narrowed and then begin to die off. The blood vessels that remain may leak blood into the retina, which causes a permanent blurring of vision.

In an attempt to compensate for the lost blood vessels, abnormal, fragile new blood vessels begin to grow on the retina. Because they are easily damaged, these blood vessels frequently rupture and leak blood into the vitreous humor (the jelly-like part of the eyeball), which causes a temporary blurring of vision. Usually this leaked blood is reabsorbed, but by then it has already caused scar tissue to form on the retina, permanently impairing eyesight, and perhaps even leading to retinal detachment.

The signs of diabetic retinopathy include blurred vision, "floaters" (spots in the visual field), and sudden loss of vision.

The most common treatment consists of laser surgery. Tiny "burns" from a laser are used to plug the leaky blood vessels. Laser surgery is not guaranteed, and like any surgery it carries risks, but it has been used for many years with a high degree of success.

Because laser surgery involves tiny "burns" to the retina, scarring from the burn itself may result in a loss of vision. Usually, however, this impairment is far less than what would have occurred if the retinopathy were allowed to advance unimpeded. Also, the benefits from laser surgery may be only temporary, and further treatment may be required--along with the same degree of risk.

In very severe or advanced cases, the vitreous humor must actually be drained from the eye and replaced with an artificial substitute.

If the retina has become detached, surgery will be required to reattach it to the back of the eye.