New research indicates that patients with herpes zoster ophthalmicus (HZO) may benefit from suppressive valacyclovir treatment, particularly over extended periods.1

In the Zoster Eye Disease Study (ZEDS), a multicentre randomised clinical trial spanning nearly seven years and including 95 sites, researchers evaluated whether daily valacyclovir (1,000 mg) could delay new or worsening eye complications – stromal keratitis (SK), endothelial keratitis (EK), iritis, or dendriform epithelial keratitis (DEK) – compared to placebo.

The study enrolled 527 immunocompetent adults with a history of HZO rash and documented active keratitis or iritis within the previous year. Participants were stratified by age at disease onset and disease duration. The primary outcome was time to first occurrence within 12 months of new or worsening SK, EK, iritis, or DEK.

While the primary endpoint at 12 months showed a modest but nonsignificant reduction in complications (28% in the valacyclovir group versus 33% in the placebo group), the secondary endpoint at 18 months demonstrated statistically significant benefits. By 18 months, complications occurred in 32% of patients taking valacyclovir compared to 40% of those on placebo, representing a 27% risk reduction.

Notably, valacyclovir also significantly reduced multiple episodes of keratitis or iritis at both the 12 and 18-month marks.

“These results support consideration of one year of suppressive valacyclovir treatment for HZO,” the researchers concluded, suggesting that ophthalmologists should consider longer-term antiviral therapy for these patients.

Reference

1. Cohen EJ, Troxel AB, Jeng BH, et al. ZEDS Trial Research Group. Low-dose valacyclovir in herpes zoster ophthalmicus: The Zoster Eye Disease Randomized Clinical Trial. JAMA Ophthalmol. 2025 Apr 1;143(4):269-276. doi: 10.1001/jamaophthalmol.2024.6114.