You may be surprised to learn that 20/20 does not necessarily mean perfect vision, as many people assume it does. It only indicates the sharpness or clarity of vision at a distance. 20/20 vision is a term used to express normal visual acuity, or the clarity or sharpness of vision, measured at a distance of 20 feet. If you have 20/20 vision, you can see clearly at 20 feet what should normally be seen at that distance. If you have 20/100 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 100 feet.
There are other important vision skills that contribute to overall visual ability, including peripheral awareness or side vision, eye coordination, depth perception, focusing ability and color vision.
Some people can see well at a distance, but are unable to bring nearer objects into focus. This condition can be caused by hyperopia, which is farsightedness, or presbyopia, which is the loss of focusing ability. Others can see items that are close, but cannot see those far away. This condition may be caused by myopia, which is nearsightedness.
A comprehensive eye examination by a doctor of optometry can diagnose and treat those conditions. In most cases, your optometrist can prescribe glasses, contact lenses or a vision therapy program that will help improve your vision. If the reduced vision is due to an eye disease, the use of ocular medication or other treatment may be used.