Previous population-based studies reporting the incidence rate of keratoconus
| Author | Country | Publication date | Studied duration (years) | Design | Population | N | Incidence* (95% CI) |
| Kennedy et al28 | USA | 1986 | 48 | Retrospective | All ages, inhabitants of Olmsted County (number not specified) | 64 | 2 (not reported) |
| Ziaei et al31 | Iran | 2012 | 1 | Prospective | 990 818, all ages, inhabitants of Yazd Province | 221 | 22.3 (19.5 to 25.4) |
| Godefrooij et al46 | The Netherlands | 2017 | 4 | Retrospective | 1 635 517 inhabitants between 10 and 40 years | 218 | 13.3 (11.6 to 15.2) |
| Hwang et al36 | South Korea | 2018 | 6 | Retrospective | 47 990 761, all ages, inhabitants | 17 931 | 5.56 (5.47 to 5.66) |
| Nielsen et al16 | Denmark | 2007 | 11 | Retrospective | 5 326 404, all ages, Danish population | – | 1.3 (1.0 to 1.7) |
| Bak-Nielsen et al32 | Denmark | 2019 | 5 | Retrospective | 5 707 251, all ages, Danish population | 1008 | 3.6 (not reported) |
| Cozma et al17 | England | 2005 | 4 | Retrospective | 470 000, all ages, inhabitants of Bradford | 197 | Asian, 32.3 (not reported) White, 3.5 (not reported) |
| Mejía-Salgado et al (present study) | Colombia | 2022 | 5 | Retrospective | 50 372 424 Colombian population | 18 419 | 10.36 (10.08 to 10.64) |
*Per 100 000 person-years.