Ongoing research continues to show the impact vitamin A has on ocular health. Vitamin A deficiency is the most common cause of childhood blindness, while appropriate intake can protect against night blindness and corneal thinning. But one thing it can’t do is ward off myopia, according to a new study.

Researchers in Australia analyzed data from 642 subjects, including dietary vitamin A intake, collected with food frequency questionnaires at ages 14, 17 and 20, and ocular parameters at age 20. They defined low vitamin intake as <600 µg/day.

The investigators found no correlation between quantitative values of vitamin A intake and refractive errors. Although they noted that those with adequate vitamin intake were less likely to have myopia, that association became insignificant after adjusting for cofounders such as ocular sun exposure level, educational level and parental myopia.

“Although the link between myopia and vitamin A does not appear to be linear, a threshold may exist for optimal vitamin A intake and axial elongation,” they researchers conclude in their paper. “Further studies incorporating more precise measurements of dietary vitamin A and adopting a broader spectrum of participants of younger ages and countries of residence would delineate associations more robustly.”

Ng FJ, Mackey DA, O'Sullivan TA, et al. Is dietary vitamin a associated with myopia from adolescence to young adulthood? Trans Vis Sci Technol. 2020;9:29..