Study Estimates Iris Color Distribution in US

Maintaining a database of eye color distribution across the US could provide a foundation for future research on the relationship between iris color and ocular diseases, as well as its potential impact on sociological interactions. Photo: Hashem F, et al. PLoS One. September 29, 2025. Click image to enlarge. It’s well-known among eye doctors that there is an association between different iris pigmentations and eye diseases, such as cataract and melanoma. Eye color is also a topic of interest among the general public purely as a matter of aesthetics and heredity. However, there is no database of iris color distribution in the population, making it difficult to better understand its role in disease epidemiology or cultural impact. In a recent study, researchers sought to identify the distribution of iris color in the United States by investigating eye color data from the Department of Motor Vehicles in each state.Iris color data of 235,423,085 driver’s license holders from 31 states was collected. A total of 19 states did not participate in the study due to special state-specific regulations or a lack of iris color information in their records. The database of eye color for current active licenses (without including any personal information) was requested. Any iris color beyond gray, blue, green, hazel or brown/black was categorized as “other.”The most prominent color among those represented by the provided data is brown/black (53%), followed by blue (23.7%), hazel (10.3%), green (9%), gray (0.7%) and other colors (3.3%).“Using information from over 230 million driver’s license holders, this report is the largest study of iris color distribution representing the United States of America, thus providing a valuable source for future eye disease and other sociological research,” the authors wrote in their PLoS One paper.When comparing the US census race data to the iris color data, what the authors found interesting was that the three states showing blue color more prominent also have different race distribution and order: Maine, Wyoming and South Dakota showed that white race was noticeably higher as a percentage of residents than the US distribution overall (96%, 94% and 88%, respectively). Addition­ally, the proportion of residents of Black race was much lower in those states than the US distribution (ranging between 1% and 2%). This may explain the dominance of blue iris color in these states.Other exceptions were noted in Missouri, Texas, West Virginia, Wisconsin, Georgia, Kentucky and Nebraska, where green was more common than hazel. These disparities in those states might be explained by immigration history, as Europeans disproportionately migrated to the Northwest and Midwest states.Regarding the reports that show an association between iris color and ocular diseases, the researchers mention in their paper a previous meta-analysis showing that cataracts were associated with darker iris colors and found no evidence of an increased risk of age-related macular degeneration (AMD) with a particular iris color. A different meta-analysis studied the potential risk factors for AMD, and their findings suggest that having darker iris colors is protective, but this relation was not statistically significant. Other reports found that AMD is related to lighter iris color. For glaucoma, one study found that high intraocular pressure is more common in African Americans with dark iris colors.While this study found a possible relationship between iris color and some ocular diseases, the work was conducted on limited populations. “Hence, the need for population-based studies to assess iris color as a potential risk factor for ocular diseases is high,” the authors concluded in their paper. “Collecting iris color and ocular diseases data nationwide at an individual level will solidify the evidence of the association of iris color with ocular diseases.”Click here for the journal source. Zhang X, Anover FA, Hung JH, et al. The relationship between retinal vascular tortuosity and retinal vasculitis. J Ophthal Inflamm Infect. October 1, 2025. [Epub ahead of print].  This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.