JAN 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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nation typically shows an area of corneal edema with Descemet's folds with fine and medium KPs on the endothelial surface taking on a ring pattern, or the KPs may be linearly displayed at the edge of a patch of endotheliitis. CMV endotheliitis in postcorneal transplantation (penetrating keratoplasty and DSAEK) can present differently or may mimic transplant rejection, Dr. Chee said and should be excluded, as the management is very different. A rapid unexplained drop in the endothelial cell count should alert the clinician to the possibility of CMV infection, which may have preceded the graft surgery or be induced possibly by transplanting CMV-infected endothelium, she said. Finally, in CMV infected penetrated keratoplasty, Dr. Chee said the area of involvement arises from the host-graft junction, and the KPs may be seen as coin-like lesions on both the donor and host cornea and may be pigmented. "There is minimal anterior chamber activity and the intraocular pressure may be elevated," she said. Verifying diagnosis "For transplant patients, a high index of suspicion is needed, but often is only suspected after a presumed graft rejection responds poorly to topical steroids," Dr. Tan said. "The current method to verify the diagnosis is to confirm the presence of CMV DNA in the aqueous humor. An AC tap sent for RT-PCR (real-time polymerase chain reaction) for CMV DNA is the most common method used today, but there is evidence that PCR may only be able to detect 40% of cases." Dr. Tan said improvement in corneal signs upon treatment with oral valganciclovir or topical valganciclovir gel together with a reduction in topical steroids can help with diagnosis. Multiple serial AC taps could be needed to monitor the condition, he said. Best treatment and risk of recurrence Oral valganciclovir 900 mg twice a day for six weeks followed by 900 mg every morning for six weeks is an effective treatment for patients with CMV endotheliitis, Dr. Chee said. "Repeat tap of the aqueous should be done to demonstrate response to therapy." After this, a decision can be made to continue or discontinue medication. When dealing with CMV acute or chronic uveitis, she said that although a 75% response is seen with antiviral therapy administered by a variety of routes over three months, there is also a 75% relapse rate once the medication is stopped. "Thus, we advocate using topical ganciclovir gel 0.15% five times daily," she said. The duration of this treatment is indefinite and frequency may be reduced. Treatment with specific antivirals should be accompanied by prescribing mild anti-inflammatory therapy, such as topical NSAIDs, Dr. Chee said. Difference between CMV and HSV infections Dr. Tan said that HSV and CMV endotheliitis can be difficult to distinguish, and an AC tap tests for both. "CMV endotheliitis appears to carry a worse prognosis than other forms of endotheliitis, including HSV, with a higher rate of recurrence and a higher risk of graft failure," he said. PCR is often the simplest and surest way to tell them apart, Dr. Chee said. "Sometimes aqueous sampling may be met with false negatives, and testing for local intraocular antibody production should be done where available (Goldmann-Witmer coefficient)," she said. Dr. Chee noted several helping points in differentiating CMV and HSV, including that anterior chamber activity tends to be more severe in HSV and could be accompanied by hypopyon formation. Flare is heavy in HSV and there is accompanying risk of posterior synechiae formation, unlike with CMV where there is minimal flare and no posterior synechiae. EW Editors' note: Dr. Chee has financial interests with Bausch + Lomb Technolas (Singapore) and Hoya Surgical Optics Singapore. Dr. Tan has no financial interests related to this article. Contact information Chee: chee.soon.phaik@snec.com.sg Tan: donald.tan.t.h@snec.com.sg

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