The medical term for farsightedness is hyperopia. As with most refractive errors, farsightedness is commonly caused by the shape of the eye. Farsighted eyes are generally shorter from front to back or because the front curvature of the eye is flatter than normal. An uncorrected farsighted eye must use the near focusing system of the eye, normally only used for close-range tasks, to assist distance vision. As a result, this places an even greater focusing effort on close-range vision. Uncomfortable symptoms and fatigue are common for the uncorrected or under-corrected farsighted eye since the visual system is in a constant state of over effort.
Clarity and comfort of vision for the farsighted person depends on their degree of farsightedness and the efficiency of their focusing system. In general, farsighted eyes always see better at far distance than at closer distances. Farsighted adults gradually see less clearly at all distances due to a natural and expected decline in the eyes close-range focusing ability over time.
Farsightedness is most commonly corrected with eyeglasses or contact lenses. If adults require different prescriptions for distance and near, special dual-focus contact lenses are now available. Less commonly, refractive surgery techniques such as LASIK, or lens replacements are also treatment options for adults.