Causes and Risk Factors of Irregular Astigmatism

Having irregular astigmatism can be frustrating because you can’t see clearly at any distance without vision correction. In irregular astigmatism, light entering the eye focuses on two or more different points instead of being bent to a single point.

This happens because of an irregular shape of the eye or the lens (the clear structure inside the eye that directs light onto the light-sensitive retina at the back of the eye). Normally, the eye is more or less round, like a volleyball, but in astigmatism it is stretched to some degree, with one area curving more than another.

In irregular astigmatism, however, the surface of the eye can be uneven in several different ways rather than just one, which can create multiple focal points and lead to blurred or distorted vision. This article reviews the common causes of irregular astigmatism and the role of genetics and lifestyle factors in this condition.

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Common Causes of Irregular Astigmatism

Irregular astigmatism can develop as a result of:

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Keratoconus

In keratoconus, the cornea becomes thinner and bulges forward, taking on a cone-like shape. This causes refractive errors such as myopia (nearsightedness, where distant objects appear blurry) as well as irregular astigmatism.

Keratoconus is thought to result from environmental factors, such as eye rubbing, in addition to genetic predisposition. Up to about 23% of people with keratoconus have a family history of the condition. Certain genes appear to make some individuals more susceptible to keratoconus, especially when combined with environmental or other contributing factors.

Some of the genes that seem to play a role in keratoconus include:

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Epithelial Basement Membrane Dystrophy

In epithelial basement membrane dystrophy, the outermost layer of the cornea does not develop normally and may break down. The epithelial basement membrane itself becomes abnormally thick and irregular, which can cause blurred or fluctuating vision. This disorder can be inherited and has been associated with mutations in the TGFBI (transforming growth factor beta–induced) gene.4

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Lifestyle-Related Risk Factors

While some risk factors for irregular astigmatism are beyond your control, in other cases the way you live can have an impact.

For example, you can choose to avoid certain refractive procedures such as LASIK, since irregular astigmatism can develop as a complication in some cases.

If you take part in activities—especially outdoor or high-impact sports—that put you at risk for eye injuries, you should always wear appropriate eye protection. Environmental factors can influence people who are predisposed to keratoconus as well as those who are not.

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Below are some potential factors to avoid:

Irregular astigmatism may be caused by accidental trauma, degenerative eye diseases, or complications from eye surgeries such as LASIK. Genetics can also play a significant role in the development of conditions like keratoconus and epithelial basement membrane dystrophy, both of which can lead to irregular astigmatism.

In addition, lifestyle factors such as frequent eye rubbing, excessive sun exposure without protection, and smoking may contribute to the development or worsening of certain conditions associated with irregular astigmatism.

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Whatever the eye problem may be, this is a delicate medical condition that requires a thorough examination and appropriate treatment by a skilled, experienced ophthalmologist using effective medical technologies that can deliver real improvement. Whatever eye disease or visual issue you are dealing with, you can book an appointment at Batal Specialty Medical Complex to get a comprehensive eye examination and begin addressing your eye problems, no matter how complex they are.

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