What is irregular astigmatism?

Irregular astigmatism is a type of eye disorder in which the surface of the cornea is affected by peaks, ridges, valleys, and other abnormal shapes. When the cornea is not uniformly smooth, light cannot be properly collected and focused on the lens. A person with mild irregular astigmatism may have slightly blurred or distorted vision, while a severe case may cause multiple images to appear in each eye that are disorienting and sometimes debilitating. The condition is generally more difficult to treat than other types of astigmatism, but specialized contact lenses and advances in surgical techniques allow many patients to enjoy at least some relief from their symptoms.

Most people who have astigmatism suffer from the regular variety. In regular astigmatism, the cornea is more or less smooth, but it is abnormally curved. Light enters the lens at a steeper or shallower angle than normal, resulting in slight distortion. In the case of irregular astigmatism, there may or may not be an angle problem. Instead, vision disturbances result from irregularities at certain points on the surface of the cornea. Bumps and drops refract light in unusual and sometimes unpredictable ways.

The underlying causes of irregular astigmatism are not always easy to determine, and many potential problems can lead to the disorder. Some people have irregular astigmatism from birth due to genetic factors. Others develop problems later in life due to eye injuries or serious infections. In some cases, surgery to correct regular astigmatism or another eye disorder can also cause accidental damage to the surface of the cornea.

A person who has irregular astigmatism usually has trouble focusing on both short-range and long-range objects. The condition is often worse in one eye than the other, and keeping one eye closed can temporarily help you see better. If the cornea is severely malformed, light can be refracted in such a way that the same image appears multiple times in different places on the lens, causing double or triple vision in one eye. Vision problems in turn can cause symptoms such as headaches, nausea, and balance problems.

While regular astigmatism can usually be corrected with glasses, contact lenses, or surgical reshaping, irregular astigmatism is usually less noticeable. A type of contact called a rigid gas permeable lens may be helpful in improving a minor problem. The lens, which is curved evenly, rests on the cornea and reduces the number of bumps and dents that affect incoming light. Delicate laser surgeries can also be performed to try to smooth the surface. The results of surgery are not always perfect, but the procedure helps most people see more clearly.

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