Study Describes Epidemiology of Congenital Color Vision Deficiency

The reason for the high prevalence of CVD in Africa, which were comparable to those of European ancestry, may be due to intermarriage and the influx of immigrants—particularly of European descent—into previously isolated communities. Photo: Wikimedia Commons. Click image to enlarge.  Congenital color vision deficiency (CVD), which impairs the ability to discriminate colors and negatively affects patients’ quality of life, is known to be primarily attributed to genetic factors, but there is limited data on the condition’s global prevalence. In a recent study, researchers sought to estimate the prevalence of CVD categorized by geographical region, ethnicity, type (deutan, protan, tritan) and severity (anomalous trichromacy, dichromacy, monochromacy). To the best of the authors’ knowledge, this systematic review and meta-analysis is the first study to estimate the global prevalence of CVD, which they found to be 2.59%. They also found that CVD varies significantly by region and ethnicity: it’s more prevalent in boys and men, individuals in Oceania and those of European descent. The paper was published on Monday in Ophthalmology.A total of 1,703,619 participants—31,493 patients from 56 studies across 21 countries and five continents—were included. The authors conducted a systematic search of online databases from 1930 to 2024 using strict inclusion criteria, limiting the analysis to studies on children and adolescents in the general population. National and regional prevalence estimates were analyzed, with additional subanalyses by ethnicity, type and severity. A random-effects model was used to calculate pooled prevalence estimates.Male individuals had higher prevalence across all types and severities (4.38% vs. 0.64% for women and girls). Deutan (difficulty perceiving green) was the most common type in both sexes, followed by protan (difficulty perceiving red) and tritan (difficulty perceiving blue). This is primarily due to the X-linked recessive inheritance of protan and deutan traits, they explained. “Deutan is more common than protan, which can be attributed to the tandem arrangement and high genetic similarity of the two genes, leading to unequal intragenic recombination,” the authors wrote in their paper. A previous study found that in male subjects, the protan-to-deutan ratio is estimated at approximately 1:2 to 1:3, varying by ethnicity, which aligns with these findings.Individuals from Europe (2.77%) and Africa (2.69%) showed the highest prevalence, while people from Oceania (4.37%) and Africa (2.86%) exhibited the highest regional rates. The high prevalence in Oceania is notable, the authors wrote, and is likely due to European immigration. The high numbers in Africa were unexpected and comparable to those of European ancestry and may be attributed to “intermarriage and the influx of immigrants, particularly of European descent, into previously isolated communities,” the authors wrote in their paper.“As positive assortative mating decreases, several studies have documented a convergence of prevalence rates toward those of European ancestry groups over generations,” they added. “Additionally, potential advantages associated with CVD may have influenced the prevalence rates, as a previous study reported that individuals with red-green CVD exhibited an enhanced ability to detect color-camouflaged objects.” Because of this, the diminishing racial differences observed in recent studies may reflect demographic shifts and increased intermarriage between ancestrally distinct populations, as well as the potential evolutionary advantages associated with CVD, the authors concluded.In terms of severity, male subjects showed the highest rates of dichromacy (1.59%), while female subjects had the highest prevalence of anomalous trichromacy (0.38%).The authors noted various shortcomings of the work, such as limited data from certain regions (notably South America), heterogeneity in data and reliance on the Ishihara test, which may underestimate the tritan prevalence.“These findings highlight the global prevalence of CVD and emphasize regional, ethnic and sex-based differences, underscoring the need for further research and targeted public health strategies,” the authors concluded.Click here for the journal source. Deun Jeong Y, Cho J, Son Y, et al. Global prevalence of congenital color vision deficiency among children adolescents, 1932-2022. Ophthalmology. July 28, 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.