Predictors of recurrent herpes simplex virus keratitis

Purpose. Determinants of the natural history of recurrent herpes simplex virus (HSV) keratitis have not been consistently established, We assessed how previous HSV eye disease affects the risk of recurrent HSV keratitis and evaluated whether demographic and other variables play any predictive role. Methods. Three hundred forty-six patients in the placebo group of the Herpetic Eye Disease Study's Acyclovir Prevention Trial who had experienced an episode of HSV eye disease in the previous year were followed up for 18 months. Recurrences were categorized according to the type of involvement. Relative rates of recurrence were compared for categories of demographic variables, types and number of previous ocular HSV episodes, previous nonocular HSV infection, and month of the year. Results. Fifty-eight (18%) of the 346 patients developed epithelial keratitis and 59 (18%) developed stromal keratitis during the 18 months of follow-up. Previous epithelial keratitis did not significantly affect the risk of epithelial keratitis (p = 0.84). In contrast, previous stromal keratitis increased the risk of stromal keratitis 10-fold (p < 0.001), and the risk was strongly related to the number of previous episodes (p < 0.001). Age, gender, ethnicity, and nonocular herpes were not significantly associated with recurrences, and no seasonal effects were observed. Conclusion. Among patients who experienced active ocular HSV disease in the previous year, a history of epithelial keratitis was not a risk factor for recurrent epithelial keratitis. In contrast, previous, especially multiple, episodes of stromal keratitis markedly increased the probability of subsequent stromal keratitis.