How are astigmatism and myopia related?
Astigmatism is a common refractive error. It occurs in about one in three Americans. Myopia is another type of refractive error. It occurs in about one in four Americans. Astigmatism can occur alone or at the same time as myopia. Astigmatism cannot cause myopia. Both are simply a type of refractive error.
What is astigmatism?
Astigmatism is usually the result of the curvature of the cornea being steeper in one region. This causes the light rays entering the eye to converge at multiple points within the eye. And it results in a blurry image.
The type of lens correction that is required to correct astigmatism is more complex than the simple spherical correction that works for myopia or hyperopia.
What is myopia?
In myopia, the eyeball is too long in relation to the curvature of the cornea and the focusing power or position of the lens. This causes the light rays entering the eye to come to a focus in front of the retina, not directly on it. This causes blur at distance.
Can you have astigmatism and myopia at the same time?
Yes, it is possible to have both astigmatism and myopia at the same time. When an individual has both myopia and astigmatism, the prescription is more complicated. This is because the corrective lens must be customized to have different strengths in different meridians.
Why doesn’t astigmatism cause myopia?
There is no scientific evidence that having astigmatism will cause or increase the risk of myopia. Astigmatism is just a different type of refractive error. It does not cause (or prevent)a person from developing myopia or hyperopia.
In order to correct for astigmatism, myopia or any visual issue, a comprehensive eye exam is necessary. At this exam, speak to your eye doctor about any concerns that you may have.
