Treatments that use tiny amounts of new drugs injected directly into the eye are having a dramatic impact on diabetic retinopathy, the most common cause of blindness in middle-age Americans. Excessive capillary growth and fluid leakage are the culprits that gradually erase vision in many diabetics. The problem arises when the retina - a high-energy tissue requiring much oxygen and nutrition doesn't get the blood it needs, so it sends out a chemical signal ordering blood vessel growth. The new vessels formed will ultimately leak, causing vision loss.

The treatment is shown to halt abnormal blood-vessel growth that gradually destroys the eye's light-sensing organ, the retina. Unlike macular degeneration, which erases central vision, diabetic retinopathy starts by ruining peripheral vision. The injections are given with tiny needles and require only a local anesthetic. Several trials were done to test the safety and efficacy of Macugen and another new eye drug, Lucentis, which is made by Genentech. So far, no major side effects from treatments with Macugen and Lucentis have been noted.