Astigmatism is a type of refractive error of the eye. It is not a disease of the eye. Rather, it is simply a problem with how the eye focuses light. Other types of common refractive errors include nearsightedness (myopia) and farsightedness (hyperopia). Frequently, astigmatism and nearsightedness or farsightedness affect one or both eyes simultaneously.
Clear and crisp vision is created by how different parts of the eye bend or refract light that passes through them. The process of refracting light to achieve perfect vision starts at the front part of the eye with the cornea. The process continues as light travels through the lens of the eye and ends with light properly focusing at a single point on the retina located at the back of the eye.
In an eye with astigmatism, there is an irregular shape of either the cornea or the lens of the eye. This irregularity makes it difficult to focus light precisely on the retina. Instead, light comes to a focus either in front of the retina or behind the retina, resulting in distorted vision. Astigmatism usually will cause blurred vision in objects being viewed at both far distances in close proximity.
The cornea is the clear, rounded-dome part of the eye covering the iris and the pupil. In a normal eye, the cornea is smooth and equally curved in all directions. As described above, this is essential for properly refracting light that enters the eye and creating clear vision. If the cornea has an irregular shape, it will not refract light properly. This type of astigmatism is called corneal astigmatism.
Just like with the cornea, the shape of the lens of the eye must be equally curved in all directions to correctly refract light and achieve perfect vision. If the lens has an abnormal shape, it will not bend light accurately. This type of astigmatism is referred to as lenticular astigmatism.
Similar to nearsightedness and farsightedness, astigmatism can usually be corrected with eyeglasses or contact lenses.
In the past, rigid contact lenses could only be utilized for astigmatism. Now, special types of soft contact lenses called toric contact lenses are available for astigmatism.
The appropriate type of corrective lens used for the correction of astigmatism, whether eyeglasses, soft contact lenses or rigid contact lenses is typically determined by the severity of the astigmatism.
Surgery is also an option for some people to correct astigmatism, including laser eye surgery (LASIK).
Importance of Starting Regular Eye Exams Early in Life
Astigmatism usually causes vision to be distorted regardless of whether the object being viewed is close or far away. The blurred vision from astigmatism may lead to squinting, eye strain and chronic headaches. For adults, these symptoms are easily identified. However, they may difficult for a child to recognize.
Astigmatism often occurs early in life. In fact, many people are born with it. Detecting astigmatism early is important for a child not only to identify and correct vision problems but also to help prevent other developmental issues.
The American Optometric Association (AOA) recommends infants have their first eye exam conducted when they reach 6 months of age. Testing for astigmatism is one of the reasons why an eye exam is important so early in a child’s life.
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