Almost half the people in the U.S. have some kind of eye defect. Nearsightedness, farsightedness, and astigmatism are the most common.
The term “20/20 vision” means a person can see at 20 feet what should normally be seen at that distance. But 20/20 only means he or she can see detail clearly. It doesn’t always mean someone has “perfect” vision. For instance, it doesn’t address things like peripheral (side) vision and color vision.
