Nearsighted and Farsighted
Nearsightedness or myopia is the ability to see clearly up close but not a distance without glasses or contact lenses. The cause is unknown, but it tends to run in families and affects more than 25 percent of the United States population.
There are two types of nearsightedness: axial myopia and refractive myopia. Don’t let the names scare you; it just means that in axial myopia the eyeball is elongated rather than spherical. Because of the shape, light rays enter the eye and focus in front of the retina instead of right on it. In refractive myopia, the refractive power of the cornea or lens is too strong, causing the same effect.
Since your vision is blurred when looking at a distance, you will need correction by wearing prescription glasses or contact lenses. Some people can benefit from refractive surgery.
Farsightedness or hyperopia is a condition in which distant objects are usually seen clearly, but close objects are blurred. The image that falls on the retina is blurred because light entering the eye is focused behind the retina instead of directly on it. This condition is caused by a cornea that is flatter than normal, a lens in the eye that is not strong enough or an eyeball that is shorter than average. Approximately 25 percent of the population in the U.S. is farsighted.
The treatment depends upon age and daily activities. Young people may not require glasses if their eyes compensate for their farsightedness with accommodation. Older patients usually require glasses, contact lenses or may benefit from refractive surgery.