Global Incidence and Prevalence of Keratoconus: A Systematic Review and Meta-Analysis

PURPOSE: To estimate global incidence and prevalence trends of keratoconus (KC). METHODS: A systematic review and meta-analysis was conducted using MedLine, Embase, and Scopus databases up to January 2024, 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. RESULTS: This study included 55 studies (53 in meta-analysis). Pooled KC prevalence was 289.1 per 100,000 persons [95% confidence interval (CI) 124.2-671.1] or 0.24% of the population. The pooled incidence was 4.0 per 100,000 person-years (95% CI 2.5-6.3). Males had higher odds of KC compared with females (odds ratio 1.10; 95% CI 1.07-1.13). The 20 to 29 age group had the highest prevalence (525.5 per 100,000 persons; 95% CI 92.6-2822.6) and incidence (20.8 per 100,000 persons-years; 95% CI 12.7-24.1). Prevalence was highest in Africa (2414.2 per 100,000 persons; 95% CI 110.1-1421.5). Prevalence estimates varied significantly across Asian subregions, with lowest prevalence observed in East Asia (12.7 per 100,000 persons; 95% CI 2.81-57.0) and substantially higher rates in West (682.0 per 100,000 persons; 95% CI 141.8-3213.1) and South Asia (1374.5 per 100,000 persons; 95% CI 537.2-3471.5). Prevalence and incidence increased over time, with highest prevalence post-2020 (1155.2 per 100,000 persons; 95% CI 32.4-29682.7) and highest incidence in 2015 to 2019 (15.23 per 100,000 person-years; 95% CI, 8.5-27.3). CONCLUSIONS: Over 23.7 million individuals globally are affected by KC, highlighting an increasing global burden of KC and emphasizing the need for further research into temporal and regional patterns to inform public health strategies and optimize patient care.