Higher incidence of penetrating keratoplasty having effects on repeated keratoplasty in South Korea: A nationwide population-based study

Purpose To investigate the incidence of corneal transplantation and identify rates and risk factors of repeated corneal transplantation in South Korea. Methods This is a retrospective population-based cohort study using the Korean National Health Insurance System database. Among the entire South Korean population (N = 51,827,813), we included those who underwent corneal transplantation more than once between January 2006 and December 2016, and analyzed the annual incidence of keratoplasty. The person-year incidence of repeated keratoplasty after the first operation was calculated according to risk factors including age group, sex, income level, surgical method, surgical etiology, and presence of major systemic diseases. Cox regression analysis was employed to evaluate the hazard ratios of those risk factors on repeated keratoplasty. Results A total of 9,452 cases of corneal transplantation occurred from January 2006 to December 2016. The average annual incidence of corneal transplantations was 1.694 per 100,000. The proportion of penetrating keratoplasty steadily decreased from 92.22% in 2006 to 77.81% in 2016. The average incidence of repeated keratoplasty among those who underwent corneal transplantation at least once was 43.24 per 1,000 person-years. Males had a greater incidence of repeated keratoplasty compared to females (males: 47.66 per 1,000, females: 36.04 per 1,000). The age group from 20 to 39 years demonstrated the lowest incidence of repeated keratoplasty at 24.94 per 1,000. Keratoconus had the lowest incidence of repeated keratoplasty (22.82 per 1,000). Conclusion This study may provide a better understanding of corneal diseases, help predict disease burden, and plan health care systems accordingly in South Korea.