Prevalence and incidence of keratoconus in Norway: a nationwide register study.

Abstract

To estimate the national prevalence and incidence of keratoconus in Norway. In this epidemiologic study, data were obtained from the Norwegian Patient Registry, which provides information from all publicly funded specialist care in Norway. Prevalence of keratoconus was estimated from the total number of patients registered with this diagnosis and incidence from the annual frequency of first-time registrations of patients up to 40years of age in the period 2010-2018. Data on age and gender of the keratoconus patients were also gathered. A total of 9832 keratoconus patients were registered. The estimated prevalence in the general population was 192.1 per 100000 (95% confidence interval (CI): 188.3-195.9), and the estimated annual incidence was 19.8 per 100000 (95% CI: 18.1-21.5). There was a predominance of males (73%), and mean age for all patients was 37.5years at first registration in this period. This study reports the frequency of keratoconus from a national patient register during a time period with available modern diagnostic tools. The estimated prevalence and incidence were higher than most previous estimates and show that keratoconus is not a rare condition. As screening was not part of the study, the true prevalence in the general population may be even higher.