Eye Care

Eye Disorders

What are refractive errors?

The following are the most common refractive errors, all of which affect vision and require lenses or surgery for correction or improvement:

astigmatism
This is a condition in which there is an abnormal curvature of the cornea making it no longer symmetrical. Astigmatisms cause blurred vision and eye strain and may be combined with nearsightedness or farsightedness. Eyeglasses or contact lenses are often prescribed to correct or improve the condition.

hyperopia
Commonly known as farsightedness, hyperopia is the most common refractive error in which an image of a distant object becomes focused behind the retina, either because the eyeball axis is too short, or because the refractive power of the object is too weak. This condition makes close objects appear out of focus and may caused blurred vision for objects at a distance, headaches, and/or eye strain. Eyeglasses or contact lenses are prescribed to correct or improve the condition.

myopia
Commonly known as nearsightedness, myopia is a condition in which, opposite of hyperopia, an image of a distant object becomes focused in front the retina, either because the eyeball axis is too long, or because the refractive power of the object is too strong. This condition makes distant objects appear out of focus and may caused blurred vision for objects at close range, headaches, and/or eye strain. Eyeglasses or contact lenses are prescribed to correct or improve the condition.

presbyopia
Another type of farsightedness, presbyopia is caused when the center of the eye lens hardens making it unable to accommodate near vision. This condition generally affects almost everyone over the age of 50 -- even those with myopia. Eyeglasses or contact lenses are prescribed to correct or improve the condition.

This page was last updated on: February 25, 2008.

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