Incidence and prevalence of keratoconus in Taiwan during 2000–2018 and their association with the use of corneal topography and tomography

Purpose: The aim of this study was to determine the age- and sex-specific incidence and prevalence of keratoconus (KC) in Taiwan and explore their association with the use of computerized corneal topography and tomography (TG). Design: This nationwide retrospective study included the Taiwanese population (N = 27,540,859) from the National Health Insurance Research Database (NHIRD) between 2000 and 2018. Method: We estimated the incidence of KC by identifying patients with newly diagnosed KC and estimated its prevalence by identifying patients who had the ICD9-CM code 371.6 or ICD-10-CM code H18.609 twice or more in NHIRD during 2000–2018. Results: The incidence of KC in Taiwan during 2000–2018 was 7075, with the incidence rate being 1.56 (95% confidence interval [CI]: 1.53–1.60) per 100,000 person-years. The prevalence of KC was 4.29 (95% CI: 4.23–4.35) per 100,000 person-years. The KC incidence rate peaked in patients aged 21–25 (6.40 in males and 3.19 in females). The overall incidence rates in males and females were 2.01 and 1.35, respectively (incidence rate ratio: 1.46), indicating that KC had a significant male predisposition. Moreover, we noted a linear correlation (R² = 0.7488) between the proportion of the use of TG and the incidence of KC. Conclusion: Estimates of nationwide population-based incidence and prevalence can contribute to a better understanding of the risk of ethnic groups and geographic locations in KC, and the trend can help physicians improve the general vision health of the population.