This is a six-month study. Eligible subjects will receive one injection of the study drug into one eye for each of three months. Visual acuity, blood pressure and eye pressure will be tested. Subjects' retinas will be examined and thickness measured by optical coherence tomography (OCT). Safety visits will be scheduled for the week after the injections. The investigators will monitor the subjects' eyes for infection and inflammation. After the three-month treatment period, subjects will return to the clinic monthly for four follow-up visits. Procedures and tests that will be performed at the follow-up visits include visual acuity, a retinal exam including OCT, blood pressure, and eye pressure.