20/20 vision is a term used to express normal visual acuity 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 a distance. If you have 20/200 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 200 feet. 20/20 does not necessarily mean perfect vision. 20/20 vision only indicates the sharpness or clarity of vision at a distance.
Some people are able to see well at distance, but are unable to focus up close. This condition can be caused by hyperopia (farsightedness) or presbyopia (loss of focusing ability due to age). Others can see well up close, but have problems with seeing things at a distance. This condition may be caused by myopia (nearsightedness).
Having a comprehensive eye exam can help diagnose your vision problem. In most cases, glasses, contact lenses or refractive eye surgery can improve vision. If reduced vision is due to eye disease, the use of ocular medication or other treatments may be used.
