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Astigmatism
Astigmatism is a type of refractive error of the eye. Refractive errors cause blurred vision. They are the most common reason why a person goes to see an eye professional.
Other types of refractive errors are:
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Farsightedness
Farsightedness
Farsightedness is having a harder time seeing object that are close than things that are far away.
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Nearsightedness
Nearsightedness
Nearsightedness is when light entering the eye is focused incorrectly. This makes distant objects appear blurred. Nearsightedness is a type of refr...
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Causes
People are able to see because the front part of the eye (cornea) is able to bend (refract) light and focus it onto the retina. This is the back surface of the eye.
If the light rays are not clearly focused on the retina, the images you see may be blurry.
With astigmatism, the cornea is abnormally curved. This curve causes vision to be out of focus.
The cause of astigmatism is unknown. It is most often present from birth. Astigmatism often occurs together with nearsightedness or farsightedness. If astigmatism gets worse, it may be a sign of keratoconus .
Keratoconus
Keratoconus is an eye disease that affects the structure of the cornea. The cornea is the clear tissue that covers the front of the eye. With this c...
Astigmatism is very common. It sometimes occurs after certain types of eye surgery, such as cataract surgery .
Cataract surgery
Cataract removal is surgery to remove a clouded lens (cataract) from the eye. Cataracts are removed to help you see better. The procedure almost al...
Symptoms
Astigmatism makes it hard to see fine details, either close up or from a distance.
Exams and Tests
Astigmatism is easily diagnosed by a standard eye exam with refraction test . Special tests are not required in most cases.
Standard eye exam
A standard ophthalmic exam is a series of tests done to check your vision and the health of your eyes.
Refraction test
The refraction test is an eye exam that measures a person's prescription for eyeglasses or contact lenses.
Children or adults who cannot respond to a normal refraction test can have their refraction measured by a test that uses reflected light (retinoscopy).
Treatment
Mild astigmatism may not need to be corrected.
Glasses or contact lenses will correct astigmatism, but do not cure it.
Laser surgery can help change the shape of the cornea surface to eliminate astigmatism, along with nearsightedness or farsightedness.
Outlook (Prognosis)
Astigmatism may change with time, requiring new glasses or contact lenses. Laser vision correction can most often eliminate, or greatly reduce astigmatism.
Possible Complications
In children, uncorrected astigmatism in only one eye may cause amblyopia .
Amblyopia
Amblyopia is the loss of the ability to see clearly through one eye. It is also called "lazy eye. " It is the most common cause of vision problems i...
When to Contact a Medical Professional
Call your health care provider or ophthalmologist if vision problems worsen, or do not improve with glasses or contact lenses.
Vision problems
There are many types of eye problems and vision disturbances, such as: HalosBlurred vision (the loss of sharpness of vision and the inability to see ...
References
Jain S, Tibrewal, Kramarevsky N, Hardten DR. Excimer laser photorefractive keratectomy In: Yanoff M, Duker JS, eds. Ophthalmology . 4th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 3.3.
Katz M, Kruger PB. The human eye as an optical system. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology . 2013 ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013:vol 1, chap 33.
Olitsky SE, Hug D, Plummer L,Stahl ED, Ariss MM, Lindquist TP. Abnormalities of refraction and accommodation. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: Elsevier; 2016:chap 620.
White PF, Scott CA. Contact lenses In: Yanoff M, Duker JS, eds. Ophthalmology . 4th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 2.7.
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Visual acuity test - illustration
Visual acuity tests may be performed in many different ways. It is a quick way to detect vision problems and is frequently used in schools or for mass screening. Driver license bureaus often use a small device that can test the eyes both together and individually.
Visual acuity test
illustration
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Visual acuity test - illustration
Visual acuity tests may be performed in many different ways. It is a quick way to detect vision problems and is frequently used in schools or for mass screening. Driver license bureaus often use a small device that can test the eyes both together and individually.
Visual acuity test
illustration
Review Date: 8/20/2016
Reviewed By: Franklin W. Lusby, MD, ophthalmologist, Lusby Vision Institute, La Jolla, CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
