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 (R ²  = 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.
(© 2023. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)