An exciting new treatment for CMV retinitis, the most common ocular infection associated with AIDS, is being used extensively at the New England Eye Center. Approved by the U.S. Food and Drug Administration, the ganciclovir implant (Vitrasert) is helping to prevent blindness in patients with CMV retinitis. Researchers at New England Eye Center invented the implant and treated over 300 patients as part of clinical trials submitted to the F.D.A.
It is estimated that up to 40 percent of people who have AIDS will develop CMV retinitis which, left untreated, results in permanent blindness. This device has been found to be more effective than previous intravenous therapies in treating the disease. The sustained-release ganciclovir implant is inserted into the vitreous (the gelatinous substance in the posterior chamber of the eye) cavity and left in place up to eight months. The pellets, only three millimeters in diameter, consist of a compressed dose of ganciclovir surrounded with a plastic coating that allows a slow, controlled release of ganciclovir to the infection site to suppress the growth of the virus.
|Figure 1: The tiny implantable device developed by scientists at the New England Center|
|Figure 2: The device is implanted into the eye in a simple surgical procedure. Once in place it releases medicine directly into the eye for many months or years.|
CMV, short for cytomegalovirus, is a widespread, and under normal circumstances, innocuous member of the herpes family of viruses. An estimated 60 to 90 percent of all adults are infected with CMV, but the virus typically lies dormant for a lifetime--unless the immune system of its human host is crippled by medications or diseases such as AIDS. Ganciclovir is an anti-viral drug which is one of only three drug therapies currently available to combat CMV infection in people who have AIDS.
"Our patients have had excellent results in maintaining vision which has allowed them to continue leading normal lifestyles," said Jay S. Duker, MD, director of the New England Eye Center and one of the leading Vitreoretinal physicians in the country performing this procedure. The New England Eye Center has performed more of these procedures than any other center in the Northeast.
"The clinical findings indicate the device is well over 90 percent effective in treating this debilitating disease when used as initial therapy." said Paul Ashton, PhD, who is a member of the Vision Research Laboratories at New England Eye Center and is one of the inventors of the ganciclovir implants. "Without the implant, it is difficult to get drugs into the eye; intravenous or oral preparations require a large dose to ensure it reaches the site, which can result in systemic side effects," added Dr. Ashton. He is applying similar techniques to the creation of sustained-release delivery systems for medications that fight glaucoma, diabetic retinal disease and other eye disease.