Vitamin A, particularly in its retinyl palmitate form, is scientifically recognized as essential for maintaining eye health. Its role in supporting the normal function of the retina, especially in the formation of rhodopsin (a pigment required for low-light and color vision), is well-established. Vitamin A deficiency can lead to xerophthalmia, which includes symptoms such as dryness, itching, and redness of the eyes, and can progress to more severe conditions like night blindness and, ultimately, irreversible blindness if untreated.

Supplementation with vitamin A has been shown in numerous clinical studies and epidemiological reports to effectively prevent and treat eye symptoms related to deficiency. The World Health Organization and other health authorities recommend vitamin A supplementation in populations at risk of deficiency to prevent ocular complications. However, for non-deficiency-related eye conditions (such as allergic conjunctivitis or general redness that is not caused by vitamin A deficiency), there is less direct evidence supporting its use. Most of the scientific support pertains to deficiency states rather than other causes of red or itching eyes.

In summary, vitamin A supplementation is strongly supported by scientific evidence for treating and preventing eye symptoms specifically linked to deficiency. Its use for general red or itching eyes unrelated to deficiency is not well-supported.