How much would vitamin a help your vision?

Not at all unless...: If you are not deficient in vitamin a then taking it will not help your vision at all. If you are deficient, then taking vitamin a will improve night vision. Extreme vitamin a deficiency, which is rare in the us, could damage the retina even leading to blindness. Besides vitamin a, related compounds, carotenoids like lutein & zaaxanthin, are good for our eyes and help prevent macular degeneration.