you have not said if the power is + or -. if it is + or hypermetropia
there are chances that she may grow out of it. . if it is - or myopia
the power tends to increase until certain age . . Refractive errors are NOT associated with poor nutrition. . Feeding your child with lots of carrots may not help these errors . . but may help her ocular surface, skin etc. . but too much of even that is not good and may be deleterious. .nothing to worry Sir . . ask them to wear glasses and have a periodic eye check up . .