Comparative recurrence rates of varicella zoster virus and herpes simplex virus keratitis.

PURPOSE: To compare the recurrence rates of herpes simplex virus type 1 (HSV-1) keratitis (HSK) and varicella zoster virus (VZV) keratitis (VZK).

METHODS

This was a cohort study of patients attending The Royal Liverpool University Hospital between January 2015 and September 2021 with virologically confirmed HSK and/or VZK with a follow-up period of 4 years. Patients with VZK were divided into those with and without a history or concurrence of herpes zoster ophthalmicus (HZO). Patients who had samples collected at each subsequent episode of keratitis were included.

RESULTS

1483 patients were included: 1002 (67.5%) with HSV-1, 472 (31.8%) with VZV and 9 (0.6%) with simultaneous HSV-1 and VZV. Of the 472 patients with VZV, 330 (69.9%) had an HZO-associated VZK (aged 62.3±19.4 years) and 142 patients (30.1%) (aged 54.9±19.2 years; p<0.01) an isolated VZK. Virologically confirmed VZK recurrence was uncommon (8/472, 1.7%) and did not differ between HZO-associated and isolated VZK (p=0.70). In contrast, virologically confirmed HSV recurrence occurred in 110/1002 (10.9%). Overall clinical recurrence (PCR positive and negative) was significantly higher in HSK than in VZK (25.1% vs 9.5%, p<0.01).

CONCLUSION

Compared with HSK, recurrence of VZK, either virologically confirmed or clinically defined, is very uncommon. A recurrent keratitis in a patient with a history of VZK or HSK may be due to HSV-1 or VZV reactivation.