The optical system of the eye is responsible for how light focuses on the retina. If the shape of the eye prevents light from focusing properly, objects may appear blurry or out of focus. This problem is known as refractive error, and millions of people are affected by it. While there are many misconceptions about it, astigmatism is simply a form of refractive error. Just like nearsightedness or farsightedness, astigmatism can be easily fixed by glasses or contact lenses. Continue reading to learn more about astigmatism, and to debunk many of the usual misconceptions about this common form of refractive error.
What Causes Astigmatism?
An astigmatism is caused by irregular curvature of the front surface of the eye. If the front of the eye, or the cornea, does not curve in a perfectly smooth manner, it causes light to bend unequally as it enters the eye’s optical system. This means light focuses unevenly on the retina, and objects may appear distorted. A common metaphor used to describe an astigmatism is that the front of the eye is shaped more like a football, with uneven curves, than a perfectly round basketball. Bottom line, astigmatism is simply a form of refractive error that can be easily diagnosed and treated in a routine eye exam. It is not an ocular health issue or eye disease.
Astigmatism is very common. In fact, almost all eyes have some degree of astigmatism, though it may be a very small amount. If the irregular curvature of the eye is enough to impact vision and cause significant blur or distortion, it can be corrected several ways. Glasses can be used to easily correct vision and prevent blurriness associated with astigmatism. Even contact lenses can be used; special lenses, called toric lenses, are designed specifically to correct vision for those who have an astigmatism. For those with mild to moderate amounts of astigmatism, toric lenses are usually an option. In cases of high amounts of astigmatism, rigid lenses such as gas-permeable contact lenses or scleral lenses may be more effective in correcting vision. Sometimes astigmatism can even be corrected with refractive laser surgery, such as LASIK. Contrary to popular belief, having an astigmatism does not mean your vision is doomed; your eye doctor can find the corrective option that works best for you.
More About Astigmatism
Astigmatism typically occurs along with another form of refractive error, such as nearsightedness or farsightedness. Even in cases where multiple forms of refractive error are present, glasses or contact lenses can be used as a corrective option. While other forms of refractive error, particularly nearsightedness, tend to progress during adolescence, astigmatism tends to remain relatively constant throughout life. Very rarely does enough astigmatism exist that clear vision is not easily achieved. However, in rare cases, high amounts of astigmatism can be associated with a progressive corneal degeneration known as keratoconus, in which large amounts of irregular astigmatism make visual correction more difficult. Luckily, this is not common, and differs greatly from simple astigmatism.