INCIDENCE OF HERPES SIMPLEX VIRUS KERATITIS AND OTHER OCULAR DISEASE: GLOBAL REVIEW AND ESTIMATES.

PURPOSE: We aimed to review available data on the incidence of herpes simplex virus (HSV) keratitis and other HSV ocular disease and to estimate the global burden of HSV ocular disease. METHODS: We searched Medline and Embase databases to October 2020 for studies reporting on the incidence of HSV ocular disease. Study quality was evaluated using a four-point checklist. Pooled estimates were applied to 2016 population data to estimate global HSV ocular disease burden. Numbers with uniocular vision impairment (any visual acuity <6/12) were estimated by applying published risks to case numbers. RESULTS: Fourteen studies had incidence data; seven met our quality criteria. In 2016, an estimated 1.7 (95% confidence interval, 95% CI 1.0-3.0) million people had HSV keratitis, based on a pooled incidence of 24.0 (95% CI 14.0-41.0; N = 2; I2 = 97.7%) per 100,000 person-years. The majority had epithelial keratitis (pooled incidence 16.1 per 100,000; 95% CI 11.6-22.3; N = 3; I2 = 92.6%). Available studies were few and limited to the USA and Europe. Data were even more limited for HSV uveitis and retinitis, although these conditions may collectively contribute a further >0.1 million cases. Based on global incidence, some 230,000 people may have newly acquired uniocular vision impairment associated with HSV keratitis in 2016. CONCLUSION: Over 1.8 million people may have herpetic eye disease annually. Preventing HSV infection could therefore have an important impact on eye health. Herpetic eye disease burden is likely to have been underestimated, as many settings outside of the USA and Europe have higher HSV-1 prevalence and poorer access to treatment.

A 20-year experience of ocular herpes virus detection using immunofluorescence and polymerase chain reaction.

BACKGROUND: To detect the presence of herpes virus in corneal scrapings/corneal grafts of suspected herpetic keratitis patients attending the outpatient department/casualty of the Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi for the past 20 years with immunofluorescence assay and to analyse the efficacy of polymerase chain reaction over immunofluorescence for routine laboratory diagnosis in some of the specimens. METHODS: Corneal scrapings and corneal grafts were collected by the ophthalmologists from 1,926 suspected herpetic keratitis patients between 1996 and 2015, among whom 1,863 patients were processed with immunofluorescence assay and 302 patients were processed with polymerase chain reaction assay for the detection of herpes virus. Of the 302 patients, clinical specimens from 239 patients were analysed by both polymerase chain reaction and immunofluorescence assay. RESULTS: Of the 1,863 suspected herpetic keratitis patients diagnosed with immunofluorescence assay, 277 (14.9 per cent) were found positive for herpes simplex virus 1 antigen. Similarly, of the 302 suspected herpetic keratitis patients diagnosed by polymerase chain reaction, 70 (23.2 per cent) were found positive for herpes simplex virus DNA. Of the 239 patients diagnosed by both polymerase chain reaction and immunofluorescence assay, 35 (14.6 per cent) were found positive with immunofluorescence assay, 59 (24.7 per cent) were found positive with polymerase chain reaction, 30 (12.5 per cent) were positive with both immunofluorescence and polymerase chain reaction assay. CONCLUSION: Efficacy and accuracy of the polymerase chain reaction assay was greater compared to the immunofluorescence assay for detection of herpes virus in corneal scrapings/corneal grafts of suspected herpetic keratitis patients. Although the immunofluorescence assay is a rapid test for the detection of herpes virus in suspected herpetic keratitis patients, a combination of polymerase chain reaction with immunofluorescence assay will provide higher reliable and accurate results.