Researchers have found that an antiviral drug, often used to suppress genital herpes, also decreases the recurrence of herpes of the eye. A paper detailing these findings is published in the July 30, 1998 issue of The New England Journal of Medicine.
Scientists found that the drug acyclovir, taken by mouth, reduced by 41 percent the probability that any form of herpes of the eye would return in patients who had the infection in the previous year. Importantly, researchers noted a 50 percent reduction in the rate of return of the more severe form of the disease — stromal keratitis — among patients who had this infection during the past year. Stromal keratitis causes scarring of the cornea, which can lead to loss of vision and possibly blindness. Recurring episodes of stromal keratitis can often result in the need for a corneal transplant.
"This drug is the first treatment that helps prevent herpes of the eye from returning," said Dr. Carl Kupfer, director of the National Eye Institute (NEI), part of the Federal government’s National Institutes of Health (NIH) and the agency that supported the clinical trial. "The results of this study should change medical practice."
Herpes of the eye, or ocular herpes, is caused by the herpes simplex virus. This infection can produce a painful sore on the eyelid or surface of the eye and cause inflammation of the cornea, the transparent tissue that covers the front of the eye. The less severe forms of ocular herpes include blepharitis, conjunctivitis, and epithelial keratitis. The more severe form of ocular herpes is stromal keratitis, which causes the body’s immune system to attack and destroy an inner layer of the cornea. Stromal keratitis is more difficult to treat than less severe ocular herpes infections.
An estimated 400,000 Americans have had some form of ocular herpes. Previous studies show that once people develop ocular herpes, they have up to a 50 percent chance of having a recurrence. This second flare-up could come weeks or even years after the initial occurrence. Each year, nearly 50,000 new and recurring cases are diagnosed in the United States, with the more serious stromal keratitis accounting for about 25 percent.
The clinical trial — called the Acyclovir Prevention Trial (APT) — followed 703 patients who had herpes of the eye during the preceding year, but did not currently have an active case of the disease. Of this number, 357 received acyclovir by mouth, and 346 received a placebo. Researchers discovered that the probability of a recurrence of any form of ocular herpes during the treatment period was significantly lower in the acyclovir group (19 percent) than in the placebo group (32 percent). This represents a reduction by 41 percent between the two groups.
Among the 703 patients, researchers examined 337 patients with a prior history of the more serious stromal keratitis. Acyclovir reduced the rate of recurrences of stromal keratitis from 28 percent to 14 percent, a difference of 50 percent between the two groups. The study medication caused no serious side effects.
"The study clearly shows that acyclovir therapy can benefit people with all forms of ocular herpes," said Dr. Kirk Wilhelmus, professor in the Department of Ophthalmology at the Baylor College of Medicine and chairman of the APT clinical trial. "Ocular herpes can be painful, chronic, and disabling. This new treatment will improve people’s quality of life. Those who have had the more serious stromal keratitis will benefit the most."
Dr. Wilhelmus noted that not all patients had the same benefit from taking acyclovir. "Patients should consult with their eye care professionals to see if prolonged use of acyclovir is right for them," he said.
Researchers also found that oral acyclovir reduced the risk of herpes infections in other parts of the body, particularly the mouth and face, by 43 percent. During the 12-month treatment period, 20 percent of patients in the group receiving acyclovir had at least one herpes infection affecting the mouth or face, as compared with 35 percent of patients in the placebo group.
Once treatment stopped, the rate of ocular herpes or herpes affecting the mouth and face did not increase, according to Dr. Wilhelmus. "During the six months after treatment ended, the percentages of herpes recurrences affecting the eye or the mouth and face was the same in both the treatment and placebo groups," he said.
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Herpes