Astigmatism is a common condition that refers to an uneven shape of the eye. People who have astigmatism have an eye shaped like a football, rather than a soccer ball. Astigmatism can be mild, moderate or severe, and is usually corrected in one’s eyeglasses or contact lenses.
If you have a cataract, this means that the lens of the eye has become cloudy, which makes the vision blurry. Cataract surgery can improve your vision by removing the cloudy lens, and replacing it with a clear lens implant. This new lens implant has a certain power (just like the lens of camera) which can compensate for whether or not you are near-sighted or far-sighted before surgery. In other words, the lens implant (intraocular lens) power can be set for good distance vision, based on special measurements before surgery. However; if a standard lens implant (no astigmatism correction) is used, this only provides sharp if you have no astigmatism.
If you have astigmatism (about 50% of people have astigmatism), then a standard lens implant can still be used, but the astigmatism would have to be corrected in your glasses (for all distances) after surgery. The other option is to use a Toric implant, which corrects for the astigmatism. This would give sharp distance vision without wearing distance glasses. The larger the amount of astigmatism, the greater the benefit of the Toric implant. Toric implants are especially useful for people with moderate to severe astigmatism.
Astigmatism also has an “axis”, meaning the “football shape” of the eye has a certain orientation to it. Likewise, the Toric lens implant has a similar axis which corresponds to this astigmatism axis of the eye. The Toric lens implant must be carefully measured and calculated, and rotated accordingly inside the eye to the correct axis in order to get the best vision.