Global Incidence of Ocular Surface Squamous Neoplasia and Histopathologic Subtypes: A Systematic Review and Meta-Analysis.

TOPIC: To estimate the global incidence trends of OSSN. CLINICAL RELEVANCE: Despite recognized associations and regional differences, there is an absence of a comprehensive global analysis of OSSN's epidemiological burden across diverse geographic and socioeconomic settings. METHODS: A systematic review and meta-analysis was conducted using Medline, Embase, and Scopus databases up to June 2025, including all age groups, sexes, and geographic regions. Pooled incidence and prevalence were estimated using random-effects models, with heterogeneity assessed by χ2 and I2 statistics. Risk of bias was conducted using the Joanna Briggs Institute Critical Appraisal Tools. RESULTS: Twenty-four studies published between 1992 and 2025, were included, encompassing 33,615 incident OSSN cases (52.9% female; mean age 57.3 years). The incidence of broad OSSN across ten studies ranged from 0.03 to 36.72 per 1,000,000 person-years. The global incidence of conjunctival squamous cell carcinoma (SCC) was 0.70 per 1,000,000 person-years (95% CI, 0.24-1.99; I2=100.0%), with pooled incidence of 1.05 per 1,000,000 person-years (95% CI 0.04-27.8; I2=99.1%) in individuals aged younger than 60 and 4.18 per 1,000,000 person-years in individuals aged above 60 (95% CI 0.77-22.7; I2=98.8%). Conjunctival SCC incidence was highest in Africa (5.04 per 1,000,000 person-years; 95% CI 2.72-9.34; I2=99.4%), followed by North America (1.29; 95% CI 0.10-17.33; I2=100.0%), and lowest in Asia (0.06; 95% CI 0.01-0.40; I2=97.5%). Incidence increased with age and was generally higher in males. Corneal SCC incidence was low (0.04 per 1,000,000 person-years; 95% CI 0.0-122.36; I2=100.0%), and only one study reported on corneal limbal SCC (0.82 per 1,000,000 person-years). No large studies reported prevalence. Overall, incidence estimates varied widely by region, sex, age, and anatomical site. Most studies used ICD codes or pathology-confirmed diagnoses, though few stratified by HIV status, age group, or anatomical site. There was a lack of data in South American countries. CONCLUSION: Available population-level data highlighted geographic variation in reported OSSN incidence, and a single incidence estimate cannot be reliably established due to inconsistent definitions and capture of OSSN subtypes. Conjunctival SCC demonstrated the highest reported incidence in African populations. There is an urgent need for standardized subtype-specific OSSN surveillance and reporting. OSSN is a rare but regionally concentrated ocular surface malignancy.