The human eye rarely continues to grow in length or size past our second decade of life. So nearsightedness, associated with excessive growth of the eye, has usually leveled off by then. The cornea ( which does most of the focusing of the eye) really doesn’t change much at all during this growth phase. But there is a second, important part of the eye that determines visual performance: the human lens. The vision changes that occur after age 40 are almost always due to age-related degeneration of this lens, not to the cornea or from further growth of the eyeball itself.
Even people with very low prescriptions can benefit if there is a compelling reason such as taking part in competitive sports, etc. But it is important to have a thorough examination including some testing not generally found in optician’s offices to determine if indeed you are a good candidate.