Important note: Information in this article was accurate in 1994. The state of the art may have changed since the publication date.
Associated Press - Tue, 20 Dec 1994
The double-layered plastic membrane, just four millimeters in diameter, delivers a powerful anti-viral drug inside the eyeball and prevents spread of a sight-robbing infection called cytomegalovirus or CMV, researchers reported Wednesday in the Archives of Ophthalmology.
CMV is a common virus that is benign in healthy people but poses a serious threat to patients whose immune system is weak, such as people with AIDS.
Dr. Carl Kupfer, director of the National Eye Institute, said about 25 percent of all AIDS patients develop CMV infection in the eye. Unchecked, the virus can inflame the retina and eventually cause blindness.
CMV infection currently is treated with daily intravenous doses of ganciclovir or foscarnet. Since AIDS patients lack the immune system response necessary to cure the virus, they must take the drugs for the rest of their lives.
Earlier studies showed that intravenous doses of the anti-viral drugs could control CMV infection in the eye for only about two months. The disease then progresses, often leading to the loss of sight.
"Some drug penetrates from the bloodstream into the eye, but not in high enough concentrations to control the disease progression as well as the drug introduced directly into the eye," said Kupfer.
To constantly bathe the inner eye with the drug, researchers developed a plastic film that can be saturated with ganciclovir. Once implanted in the eye, the drug is slowly released, controlling the infection.
In the clinical research, 26 patients recently diagnosed with CMV infections of the retina were identified. Among the patients there were 30 infected eyes.
Fourteen of the eyes underwent immediate surgery and the drug release device was implanted. The other 16 eyes were examined every two weeks until progression of disease was detected and the patients were then offered the ganciclovir implant. Fourteen received the implants.
CMV infection commonly spreads from one eye to the other and during the course of the study 11 more eyes received the implant.
Kupfer said that at the end of eight months, the CMV infection gotten no worse in any of the eyes with the implants. In effect, the virus was held in check.
"This is the first time that infection of the retina has been treated by an implant that allows a drug to be released within the eye," said Kupfer. "This allows a very high concentration within the eye."
Though the treatment does not eradicate the CMV, Kupfer said, "if you can prevent the disease from manifesting itself for 240 days, that's important."
In clinical application, Kupfer said, the implant would be replaced about every eight months.
The drug-releasing membrane is implanted during a one-hour operation under local anesthetic. Though some patients experienced blurred vision after the procedure, the side effect cleared up within four weeks, he said.
Dr. Daniel F. Martin of Emory University School of Medicine, a coauthor of the research, reported that of 39 eyes treated, 34 retained nearly perfect vision.
Blindness caused by CMV infection is becoming an increasingly serious problem among people living with AIDS, said Kupfer.
"The longer they live, the greater the chance that they will get this infection not only in one eye, but in both eyes," he said.
The implant is now only in experimental clinical trials and has not yet been approved for general use by the Food and Drug Administration. Two additional clinical trials are under way and application for FDA approval of the implant may be made after those trials.
Copyright (c) 1994 - Associated Press. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Permissions Desk, The Associated Press, 50 Rockefeller Plaza, New York, NY 10020.
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Copyright © 1994 - Associated Press. Reproduction of this article (other than one copy for personal reference) must be cleared through the AP Permissions Desk.
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