Nationwide study of the association between keratoconus and autism spectrum disorder.

Purpose: To examine whether there was an association between keratoconus and autism spectrum disorder (ASD) in Norway and compare to the general population.

Setting: The total population of Norway, including all individuals with ASD and keratoconus.

Design: Cross-sectional epidemiological study.

Methods: Data was obtained from the Norwegian Patient Registry, which provides information from all publicly-funded specialist care. The keratoconus prevalence among persons with ASD, was estimated from the total number of individuals with keratoconus in the period 2010-2019, and compared to the prevalence in the general population of Norway during the same time period.

Results: A population-based sample in Norway identified 23 763 persons with ASD, equivalent to 0.5% of the population, and of these 115 (0.5%) had a diagnosis of keratoconus. The average age at keratoconus diagnosis among individuals with ASD was 27.3 years, and 83.5% of those diagnosed with both ASD and keratoconus were men. During the same time period, the prevalence of keratoconus in the general population of Norway was 0.2%, resulting in an odds ratio of 2.5 (95% CI: 2.0-3.0).

Conclusion: Based on our findings, people with ASD have significantly higher prevalence of keratoconus compared to the general population of Norway. This implicates that one should have increased awareness for keratoconus and low threshold for corneal tomography in patients with ASD.