Age distribution and characteristics of choroidal nevi in 35 559 individuals: A nationwide study using optometry...

To examine the age distribution and characteristics of choroidal nevi in a large nationwide sample.

We included all individuals who underwent fundus photography in a nationwide chain of optometry stores during a 5-week period in 2023. Non-mydriatic 45° or 60° digital fundus images were reviewed asynchronously by a subspecialized ocular oncologist. All images with suspected choroidal nevi, defined as a pigmented choroidal lesion of slate blue or green grey colour, were jointly re-examined by two ocular oncologists and subsequently reviewed by a third ocular oncologist for confirmation and detailed characterization. Age, sex and geographic distribution were correlated with demographic data from the predominantly white Danish population.

Fundus images from 35 559 individuals aged 5-100 years (median, 54 years; interquartile range, 40-56 years) were included, representing 0.60% of the Danish population. Gradable images of both eyes were available in 31 129 participants, and at least one gradable image was available in 33 588 participants. In total, 852 nevi were identified, corresponding to a crude prevalence of 2.54% (95% CI 2.37%-2.71%). Prevalence increased during the first 5 decades of life (0%, 0.74%, 1.40%, 2.23%, 2.87%, 2.94%, 2.88%, 2.53% and 2.51% in individuals aged <10, 10-20, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80 and >80 years, respectively). Median largest basal diameter of nevi was 1.75 mm (interquartile range 1.33-2.30) and was only weakly associated with age (R² < 0.01; p = 0.041). According to the MOLES system, most nevi were classified as common (90.8%) or low-risk (5.28%), with fewer graded as high-risk (2.70%) or probable melanoma (1.17%).

The prevalence of choroidal nevi increased throughout the first 5 decades of life. Most nevi were small and lacked risk factors for malignant transformation. This indicates that the emergence of a choroidal nevus can be expected to occur by the age of 50. If supported by longitudinal studies, these findings could inform risk-based surveillance strategies to optimize resource allocation.