What is a Refractive Error?
Refractive error is a term that is used to describe an inability of images
to focus properly on the retina of the eye. The goal of glasses, contact
lenses, and refractive surgery is to correct or improve these errors by
helping images to focus closer to or onto the retina.
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MYOPIA
The refractive error known as myopia or nearsighedness occurs
when the eye is too long or the cornea is curved too steeply. The
images focus in front of the retina causing distant objects to appear
blurry.
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HYPEROPIA
The refractive error known as hyperopia or farsightedness
occurs when the eye is too short or the cornea is too flat. The
images focus beyond the retina and cause close objects to appear
blurry.
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ASTIGMATISM
The refractive error known as astigmatism occurs when
the cornea is not round like a basketball, but curved more like
a football. The images focus at different planes and cause objects
to appear blurry both at distance and near. Often people have
astigmatism as well as myopia or hyperopia.
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PRESBYOPIA
The refractive error known as presbyopia begins to occur
in most people around age 40 when the lens of the eye begins to
lose its elasticity. It is a normal aging process of the eye which
makes it difficult to focus on near objects and is usually corrected
with bifocals or reading glasses.
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