Prevalence, Characteristics and Evolution of Mpox-Related Ophthalmic Disease: A Prospective Cohort Study in South-Kivu, Democratic Republic of the Congo (MBOTE-EYE)

BackgroundMpox-related ophthalmic disease (MPOXROD) ranges from mild conjunctivitis to sight-threatening keratitis, however, data based on systematic ophthalmological assessment are scarce. We aimed to characterise the prevalence, features, and temporal evolution of MPOXROD during a clade Ib mpox outbreak. MethodsWe conducted MBOTE-EYE, a prospective ophthalmological sub-study, nested within a clinical characterisation cohort in Kamituga, South-Kivu, Democratic Republic of the Congo. All hospitalised patients with mpox confirmed by PCR in the prior 48 hours were eligible. Participants underwent comprehensive ophthalmological examination at enrolment, discharge, and days 29 and 59 post-diagnosis. Conjunctival swabs were collected for monkeypox virus PCR testing. MPOXROD was defined as conjunctivitis, scleritis, keratitis, uveitis, or optic nerve involvement. Risk factors were assessed using mixed-effects Poisson regression. FindingsBetween 28 October 2024 and 30 June 2025, 310 participants were enrolled (median age 14 years, IQR 2.5-25.0; 53.5% female, n=166/310). At enrolment, conjunctivitis was present in 36.1% (95% CI 31.0-41.6%, n=112/310), keratitis in 7.7% (95% CI 5.3-11.3%), and anterior uveitis in 0.6% (95% CI 0.2-2.3%). Overall, 43.2% (95% CI 37.8-48.8%) developed MPOXROD during follow-up, most often bilaterally. Visual acuity <8/10 occurred in 22.9% (95% CI 17.6-29.2%, n=24/310), and persistent blindness in 0.9% (95% CI 0.24-5.5%, n=2/225), due to ulcerative keratitis. Periorbital lesions (adjusted risk ratio [aRR] 2.82, 95% CI 1.40-5.69) and severe malnutrition (aRR 5.06, 2.25-11.38) were independently associated with MPOXROD. Conjunctival swabs with PCR Ct values < 25 occurred exclusively in participants with active MPOXROD. InterpretationOphthalmic involvement in clade Ib mpox is common and frequently bilateral, with a substantial burden of keratitis and risk of vision loss, particularly in young children and severely malnourished individuals. These findings highlight the need for systematic eye examinations in mpox care and provide critical evidence to inform future trials of targeted ophthalmic therapies. FundingNone of the funders had a role in study design, analysis, interpretation, or writing.