The Global Epidemiology of Scleritis: A Systematic Review and Meta-analysis

Purpose: Scleritis, a severe inflammatory condition of the sclera, causes significant ocular pain and potential tissue damage. Often linked with systemic diseases, scleritis can be either infectious or noninfectious. Despite its clinical importance, the global incidence and detailed epidemiology of scleritis are poorly understood due to its heterogeneity and rarity. This systematic review and meta-analysis aim to elucidate the worldwide incidence and epidemiological trends of scleritis, examining variations across geographic regions, etiologies, and time periods. Design: Systematic Review and Meta-analysis. Clinical Relevance: Understanding scleritis epidemiology is crucial for enhancing diagnostic accuracy and treatment, especially concerning systemic illnesses commonly associated with this condition. Identifying epidemiological trends can inform healthcare policies and resource allocation, improving patient outcomes. Methods: We systematically reviewed literature across databases, including Embase, PubMed, Virtual Health Library, The Cochrane Library, and medRxiv. Population-based, cohort, case-control, cross-sectional, and claims database studies reporting the frequency, prevalence, or incidence of scleritis diagnosed through clinical or imaging techniques, were included. The screening was based on titles and abstracts, followed by a full-text review. We assessed the risk of bias using standardized tools and systematically extracted data for qualitative and quantitative synthesis. This review is registered with PROSPERO (CRD42022330948). Results: This review included 74 studies with 169,871 scleritis patients. The incidence was 2.67 per 100,000 in ophthalmological centers and 1.38 per 100,000 in broader population-based studies, both showing a decreasing trend over time. The patient population was predominantly female (67.24%), with an average age of 48.3 years. Epidemiological patterns were significantly influenced by etiology, geographic region, and publication period, with idiopathic cases being the most common. Scleritis was notably associated with systemic diseases such as rheumatoid arthritis, granulomatosis with polyangiitis, Sjögren's syndrome, sarcoidosis, and infectious agents like Mycobacterium tuberculosis and herpes virus. Conclusion: This is the most extensive study on scleritis to date, providing comparative insights across geographic regions, age groups, and genders. Our meta-analysis highlights significant regional differences in scleritis incidence, reflecting variations in medical practice, access to care, and potential genetic and environmental factors. These findings underscore the need for further research to explore these patterns and their global health implications.