|Classification and external resources|
Hyperopia (also called hypermetropia or far-sightedness) is a problem with the focusing ability of the eye. People with hyperopia have an easier time seeing things that are far away than seeing things that are up close. Inside the eye is the lens which can change shape to change the focusing power of the eye and make things look clear. Someone who is not far-sighted only needs to use their lens to make close objects look clear. But for someone with hyperopia, their lens has to do that even when they're looking far away, and it has to work extra hard to make close objects look clear.
Many people with small amounts of hyperopia don't have any problems seeing up close because it's easy for their lens to focus all the time, especially when they're children. But if they have more hyperopia, they often get headaches and eyestrain when they read for a long time because the muscle that controls the lens gets tired.