Eyeworld

EW CORNEA 22 June 2011 Topical HSV medication ushers in new thinking on treatment H erpes ocular infection is one of the leading causes of infectious corneal blindness in the United States and Europe, ac- cording to Vincent P. de Luise, M.D., assistant clinical professor of ophthalmology, Yale School of Medi- cine, New Haven, Conn. "By the age of 5, two out of three people have positive viral titers to herpes sim- plex, and by the time we're adults it's virtually ubiquitous," Dr. de Luise said. "Upward of 1% of people can get herpes keratitis—that could be recurrent throughout their lives." Considering the old guard While a new topical antiviral med- ication, ganciclovir gel (Zirgan, Bausch & Lomb, Rochester, N.Y.), has recently made inroads, earlier options were limited. One of the older medicines, idoxuridine (Stoxil, GlaxoSmithKline, Middlesex, U.K.), had drawbacks and is no longer available, and two other medicines, trifluridine (Viroptic, Monarch Pharmaceuticals, Bristol, Tenn.) and vidarabine (Vira-A, Monarch Pharmaceuticals), were less than ideal. "Those three medicines, idox- uridine, trifluridine, and vidarabine, do not work specifically on viral cells," Dr. de Luise said. "Instead, they kill both normal cells and vi- rally infected cells." He finds that this leads to a significant amount of toxicity to the surface of the eye. With these older medications, practitioners were seeing corneal ep- ithelial toxicity in the form of punc- tate keratitis and even more serious effects. "With idoxuridine we were seeing punctal stenosis or closure of one of the lacrimal ducts from the toxicity of the agent," Dr. de Luise said. In addition to being a non-selec- tive antiviral, trifluridine has the dis- advantage of containing the toxic preservative thimerosal. "It's one of the few ophthalmic medicines left that has thimerosal as a preserva- tive," Dr. de Luise said. Unlike the other agents, the new topical ganciclovir targets the HSV virus itself. "Ganciclovir gel works through viral thymidine ki- nase so it's specific for viral cells," Dr. de Luise said. "Therefore it's much less toxic than the older ocu- lar topical antivirals." Dr. de Luise finds that another advantage of ganciclovir gel over tri- fluridine is the dosing schedule. "The dosing schedule of trifluridine is nine times a day, which would be about every 2 hours in an 18-hour waking day," Dr. de Luise said. "For ganciclovir gel, the FDA label is five times a day for the first week and then three times a day for the sec- ond or until there is complete ep- ithelial healing." Solo treatment approach With the availability of ganciclovir gel, treatment preferences for HSV keratitis are now somewhat in flux. "Some physicians feel that virtually any case of herpes simplex keratitis should be treated not only with top- ical agents, but also should be given adjuvant therapy with oral antiviral medication," Dr. de Luise said. "When we are talking specifically about epithelial disease, other physi- cians don't necessarily feel that way." He pointed out that one of the downsides of the oral antiviral med- ications is that they carry the rare risk of renal toxicity. Dr. de Luise generally opts for ganciclovir gel alone for primary ep- ithelial disease. He does, however, couple drug treatment with minimal wipe debridement. "That very quick act of using a sterile calcium alginate by Maxine Lipner Senior EyeWorld Contributing Editor Current treatment of herpes simplex virus (HSV) keratitis H erpes simplex keratitis (HSV) is one of the most challenging enti- ties that faces ophthalmologists. Topical antivirals have had significant toxi- city, and the more recent trend has been to use oral antiviral agents to manage HSV keratitis. Ganci- clovir was recently approved for use in the eye in the U.S. and is the first new topical ophthalmic antiviral in over 30 years. I have asked two corneal experts to com- ment on their approach to HSV keratitis and how, if at all, this new medication has changed their management. Edward J. Holland, M.D., cornea editor A geographic ulcer with fluorescein staining of the base of the ulcer and rose bengal staining of the peripheral terminal end bulbs Source: Vincent P. de Luise, M.D. Herpes simplex epithelial keratitis with lacy, rose bengal staining of the terminal end bulbs of the dendrite continued on page 23 Cornea editor's corner of the world

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