Astigmatism Overview (cont.)
Andrew A. Dahl, MD, FACS
Andrew A. Dahl, MD, is a board-certified ophthalmologist. Dr. Dahl's educational background includes a BA with Honors and Distinction from Wesleyan University, Middletown, CT, and an MD from Cornell University, where he was selected for Alpha Omega Alpha, the national medical honor society. He had an internal medical internship at the New York Hospital/Cornell Medical Center.
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
In this Article
- Astigmatism introduction
- What is the definition of astigmatism?
- What are the different types of astigmatism?
- What causes astigmatism?
- Who is at risk for astigmatism?
- What are symptoms of astigmatism?
- What are signs of astigmatism?
- What tests are used to diagnose astigmatism?
- What is the treatment for astigmatism?
- What is the prognosis for astigmatism?
- Can astigmatism be prevented?
- Find a local Eye Doctor in your town
What causes astigmatism?
Most astigmatism does not have a recognized cause, but merely is an anatomical imperfection in the shape of the cornea, in which the front curvature of the cornea is toric, rather than spherical. A small amount of astigmatism is considered normal and does not represent a disease of the eye. This type of astigmatism is extremely common and frequently is present at birth or has its onset during childhood or young adulthood. There is some hereditary basis to most cases of astigmatism, and most people with astigmatism have it in both eyes. Astigmatism is often associated with myopia (nearsightedness) or hyperopia (farsightedness). Astigmatism can increase in amount during the growing years.
In regular astigmatism, the meridians in which the two different curves lie are located 90 degrees apart. Most astigmatism is regular. In irregular astigmatism, the two meridians may be located at something other than 90 degrees apart, or there are more than two meridians.
A scar in the cornea, resulting from an injury or infection, or a disease called keratoconus may also cause astigmatism. This type of astigmatism is usually irregular.
Who is at risk for astigmatism?
Individuals with a family history of high degrees of astigmatism or keratoconus are at risk for astigmatism. People who use power tools without safety glasses are subject to the type of injuries that may cause acquired astigmatism.
What are symptoms of astigmatism?
In an eye with astigmatism, vision is blurred due to the inability of the optical elements of the eye to focus objects into a sharp image on the retina. In astigmatism, a point of light is focused and perceived as a line, rather than as a point. Astigmatism makes it difficult to see fine details, both close-up or at a distance. Small amounts of astigmatism may not be noticed at all. Sometimes uncorrected astigmatism can lead to eye strain, eye fatigue, squinting, or headaches in addition to blurring and distortion of vision at all distances.
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