"Low vision" is a medical term that is defined as chronic disabling
visual impairments that cannot be corrected with glasses, contact
lenses, or medical or surgical treatment. Eighty percent of people with
low vision are over age sixty-five, and most of these developed low
vision late in life.
Children have the ability to change the eye's focus over a large range, so they can get extremely close to an object and still keep it in focus. But adults lose that ability because of hardening of the eye's lens with age. Consequently many adults require strong glasses or magnifiers to focus on closely viewed objects.