Colour vision deficiency is associated with increased prevalence of amblyopia, strabismus and ametropia: a large population study.

Aims: To examine the association between colour vision deficiency (CVD) and other ophthalmic disorders including amblyopia, strabismus and ametropia in a large population study.

Methods: The retrospective, cross-sectional study included 916 388 Israeli army male recruits who had their premilitary medical assessment at the age of 16-18 years from 2000 to 2020, analysing the prevalence of ophthalmic disorders including amblyopia, strabismus and ametropia in army recruits with CVD compared with all other recruits with normal colour vision. Demographic and socioeconomic data were also collected.

Results: The prevalence of amblyopia (1.28% vs 0.71%, p<0.001), strabismus (1.09% vs 0.83%, p<0.001) and ametropia (moderate-less than 6.00 diopters, 35.05% vs 30.50%, p<0.001 and high-higher than 6.00 diopters, 3.18% vs 2.30%, p<0.001) were all higher among 28 001 (3.06%) army recruits with CVD compared with all other individuals with normal colour vision. CVD was more common in individuals with a higher socioeconomic status (high 3.15% vs low 2.93%, p<0.001) and varied according to recruits' origin. It was most frequent in individuals whose mother was born in the former Soviet Union (4.98%) compared with other European countries (3.89%), North America (3.28%), Asia (2.78%) and Ethiopia (1.63%).

Conclusion: CVD is associated with an increased frequency of amblyopia, strabismus and ametropia, which can all impart vision difficulties besides colour vision impairment alone.