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Refractive Errors
For clear eyesight, the cornea (the clear front window of the eye) and the lens (behind the pupil ) must properly focus light rays on the retina which forms the back wall of the eye. If your eye cannot focus image on the retina, then there is a refractive error.

There are 4 common types of refractive errors: myopia, hyperopia, astigmatism and Presbyopia.

Myopia ( nearsightedness ), hyperopia ( farsightedness), and astigmatism are caused by differences in the length or the shape of the eye. On the other hand, presbyopia (aging eye) occurs when the lens inside the eye loses its focusing ability for near vision.

Nearsightedness, farsightedness, astigmatism and presbyopia usually can be corrected with eyeglasses, contact lenses, or refractive surgery.

Read the following articles to find out more about the causes and treatment of these four types of refrective errors.

Myopia (Nearsightedness)
In myopia, the eyeball is too long for the normal focusing power of the eye. As a result, images of distant objects appear blurred...read more

Hyperopia (Farsightedness)
In this condition, the eyeball is too short for the normal focusing power of the eye. In children, the lens in the eye accommodates for this error and provides clear vision for distance and usually near viewing, but with considerable effort that often causes fatigue and sometimes crossed eyes (strabismus)...read more

Astigmatism results primarily from an elongated shape of the front surface of the cornea, which usually causes vision to be blurred or distorted to some degree at all distances. Persons with astigmatism typically see one direction of lines more clearer than the lines 90 degree away from it...read more

As people age, they often experience difficulty in focusing their eyes for reading and close work. This condition is called presbyopia ( aging eyes). It is easily corrected with glasses...read more

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