Herpes simplex virus (HSV) can be particularly devastating on the clarity of the cornea and on vision. It is well known that HSV keratitis can recur weeks, months, and even years after the first “acute” episode. Each recurrence of herpes comes with the added risk of new corneal scarring, worsening of vision, and the possible need for a corneal transplant. In addition to treating the acute phase of this condition, if possible, we would also like to do as much as possible to prevent recurrences. This is the reason long term oral antiviral suppression is used by some ophthalmologists.
The research on HSV can be confusing due to the inherent difficulty of studying HSV and the variablity of the disease. Cochrane is a collaboration of indepent global researchers that help to answer questions such as these to make health care decisions better. In June 2016, they performed a review of three studies that examine if oral antiviral medications such as acyclovir helped to prevent recurrence of HSV following corneal transplantation. They found that oral antivirals do show some evidence of preventing recurrence of HSV in the new cornea and of reducing the chance of graft failure. These results were true for follow up for up to two years (the longest follow up time) after the transplant.
Right here in Houston, I follow the reasoning of these studies to recommend that patients with a clear diagnosis of HSV cornea problems should stay on oral antiviral medications such as acyclovir or valacyclovir for long term prophylaxis against recurrence whether or not a corneal transplant has been performed.