Updated: Aug 4, 2019
What is astigmatism? Most astigmatism occurs when the cornea has a greater curvature in one dimension than another. Because of this, the eye is never completely in focus. For example, the astigmatic eye might see distance in the horizontal dimension, and near in the vertical dimension. As a result, images are in focus, and out of focus, at the same time. Unlike a nearsighted person, who sees perfectly well at near, an astigmat never sees well at any distance unless the astigmatism is corrected.
There is very little positive to say about astigmatism. Astigmatism distorts images, making them look smeared or elongated, too skinny or too wide. Contact lenses for astigmatism are often difficult to fit, and work imperfectly. Glasses for astigmatism are thick and can distort images.
If you have more than 1.00 Diopter of astigmatism, you have the opportunity minimize your astigmatism during cataract surgery.
Astigmatism management during cataract surgery relies on toric lenses. Toric lenses have their own astigmatism, and are placed such that the axis of their astigmatism is exactly opposite from the axis of there cornea’s astigmatism.
About a third of patients have enough astigmatism to treat with a toric lens. If you want to get the best result out of your cataract surgery, it is imperative that you know if you are one of the 1/3 of patients who would benefit from astigmatic management. To calculate your potential astigmatism, and see a simulation of the effect it would have on your vision, click on astigmatism on the toolbar above.
Christopher Kuntz, MD is a cataract surgeon from Seattle, Washington. He is the author of the patient education website https://www.cataractsurgerydesign.com.