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ASTIGMATISM - SFA

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					JULY 2010                                                                                   AUDRA BISHOP



                                     ASTIGMATISM

ASTIGMATISM
Astigmatism occurs when the cornea (the front
surface) of the eye has an irregular shape—
curving in one direction more than the other. This
irregularity results in the eye being unable to focus
sharply at any distance. The light rays that enter
the eye are bent unequally, which means the
focus is not at a single point, but several points in
all directions (Mayo Clinic, 2010; Cassin, B. &
Rubin, M. L., 2006).


SYMPTOMS & FREQUENCY
                                                               Light rays hitting several points on retina

Some symptoms of astigmatism include: distortion
in portions of your visual field, blurred vision,
eyestrain, and frequent headaches. Astigmatism is
a refractive error—which means that light rays are
                                                        CAUSES
not properly refracted onto the retina due to a
curving or uneven surface of the lens or the cornea.    Astigmatism is typically hereditary. Most
If the cornea has a distorted shape, you will have      people are born with an oblong cornea which
corneal astigmatism and if the lens has a distorted     may cause the vision problem to become
shape, you will have lenticular astigmatism. Either     worse over time. However, astigmatism may
type will cause blurred vision and the blurred vision   also develop after an eye injury, disease, or
may occur in more than one direction—horizontally,      surgery, particularly if the cornea is involved.
vertically, or diagonally (All About Vision, 2010).     Contrary to popular belief, astigmatism is not
                                                        caused by reading in low light, sitting too
Astigmatism is a very common vision condition.          close to the television, or squinting (All About
The majority of people have some degree of              Vision, 2010).
astigmatism. Small amounts of astigmatism
typically don’t affect vision and will not require
treatment. However, larger amounts of
astigmatism will cause distorted and/or blurred
vision and require treatment (American Optometric
Association, n.d.).

Astigmatism may also occur with other vision
conditions such as nearsightedness (myopia) which
happens when the cornea is curved too much and
the eye is longer than normal. Astigmatism may
also occur with farsightedness (hyperopia) which
happens when the cornea is curved too little and
the eye is shorter than normal (Mayo Clinic, 2010).
JULY 2010                                                                              AUDRA BISHOP



                                         ASTIGMATISM
                                                        VISUAL IMPLICATIONS
                                                        Individuals with astigmatism may experience
                                                        fluctuations in visual abilities and experience
                                                        headaches and eye strain related to the blurred
                                                        vision that accompanies astigmatism. With
                                                        proper treatment, these issues should subside
                                                        and not interfere with daily activities (Lueck,
                                                        2004).

                                                        TREATMENT OPTIONS
                                                        There are several treatment options for
                                                        astigmatism:
    Picture of cornea with astigmatism (note curved
           appearance) and a normal cornea.                    Contact lenses: can correct both
                                                                corneal and lenticular astigmatism—
                                                                there are a wide variety of lenses
                                                                available to address specific needs
                                                               Eyeglasses: alternative to contact
                                                                lenses that can effectively compensate
                                                                for the uneven shape of the eye
                                                               LASIK surgery: laser eye surgery that
                                                                can effectively re-shape the cornea and
                                                                correct the astigmatism
                                                               Photorefractive keratectomy (PRK): a
                                                                surgeon removes the outer layer of the
                                                                cornea and uses a laser to change the
                                                                curvature of the cornea
                                                               LASEK surgery: similar to LASIK, but a
                                                                much thinner layer of cornea is folded
                                                                back before re-sculpting, which makes
     Picture on left shows what sign looks like with
                                                                the eye less vulnerable to injury
  astigmatism and on right shows what sign looks like
            with correction for astigmatism.            Individuals should consult with their optometrist
                                                        to discuss which treatment option is best suited
                                                        to address his/her vision problem (American
                                                        Optometric Association, n.d.).
MONTH DAY YEAR
References

All About Vision. (2010). Astigmatism. Retrieved July 1, 2010, from

       http://www.allaboutvision.com/conditions/astigmatism.htm

American Optometric Association. (n.d.). Astigmatism. Retrieved July 1, 2010, from

       http://www.aoa.org/x4698.xml

Cassin, B. & Rubin, M. L. (Eds.). (2006). Dictionary of eye terminology (5th ed.).

       Gainesville, FL: Triad Publishing Company.

Lueck, A. (Ed.). (2004). Functional vision: A practitioner’s guide to evaluation and

       intervention. New York, NY: American Foundation for the Blind.

Mayo Clinic. (2010). Astigmatism. Retrieved July 1, 2010, from

       http://www.mayoclinic.com/health/astigmatism/DS00230




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