Astigmatism - Causes and Treatment
"Astigmatism" is a big word for a relatively common problem. Astigmatism is one of the more common vision problems patients are diagnosed with. Many are diagnosed however and fail to realize what the problem is.
Typically astigmatism accompanies a diagnosis of farsightedness or nearsightedness. It usually results from the cornea being unevenly shaped. If you cut a basketball in half, the perfect half dome would be a cornea without astigmatism. If you cut a football in half, the uneven done would be a cornea with astigmatism. Now your cornea does not actually look like a football. This is just a simple analogy for you to understand the difference in corneal surface. Astigmatism is an irregular corneal surface and results in vision problems or difficulty focusing. When the cornea is oblong shaped light tends to focus on two points at the back of the eye instead of a single point. This may compromise the vision. Other times astigmatism results when the lens located behind the cornea is shaped abnormally.
Signs and Symptoms
Most people who have very mild astigmatism don't even realize it. For some the only symptom is slightly blurry vision, like the edges of letters on street signs being shaded or doubled almost. For others headaches and eyestrain are common side effects of astigmatism. Patients with more moderate astigmatism may notice some distortion or blurring of their vision at near and far distances.
Children are just as likely to develop astigmatism as adults, though the condition is more commonly diagnosed in adults as children are often unaware they have a problem with their eyesight. Some children have difficulty seeing well when playing sports or while in school. For this reason most eye doctors recommend a routine eye exam before school age.
The most common cause of astigmatism is an irregularly shaped cornea. Usually in patients with astigmatism the cornea is shaped similarly to a football than a sphere. This may result in vision problems or difficulty focusing. When the cornea is oblong shaped light tends to focus on two points at the back of the eye instead of a single point. This may compromise vision minimally.
There are two forms of astigmatism, regular and irregular. With regular astigmatism, the meridians housing the curves of the cornea are roughly 180 degrees apart. In irregular astigmatism, the meridians are located at any other distance and typically there is more than one meridian. Regular astigmatism is more easily corrected than irregular astigmatism.
Risk Factors for Astigmatism
Most people inherit the likelihood they will develop astigmatism. Others will develop an astigmatism resulting from an injury to the eye or cornea. Still others may develop astigmatism resulting from surgery to the eye or from a disease resulting in progressive thinning or coning of the cornea called keratoconus.
Regular astigmatism is one of the simpler vision problems to correct. Most patients will realize a complete relief of symptoms simply by using corrective lenses such as glasses or contact lenses. Most patients with astigmatism will receive a prescription with three parts that includes correction for near or farsightedness plus the astigmatism and what meridian the curvature of the astigmatism sits at, an axis between 1-180.
Several years ago patients with astigmatism were not good candidates for soft contact lenses and had to either wear glasses only or wear rigid contact lenses. Today patients with astigmatism can be fitted successfully into toric soft contact lenses. However, patients with severe astigmatism and keratoconus still need to be fitted into rigid contact lenses. Rigid contact lenses resurface the corneal surface, changing it from the football shape into the basketball shape and hense eliminating the astigmatism. Some doctors may recommend refractive surgery to correct very severe cases of astigmatism. This may include LASIK surgery to completely resolve or moderate your condition.
Astigmatism is easily diagnosed during a comprehensive eye exam. If you are having problems with your vision, experiencing frequent headaches, having trouble focusing or seeing hazy vision, it is important you contact your eye care professional for a complete evaluation. Your doctor can recommend the most appropriate form of treatment based on the severity of your condition and medical history.
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