As we've mentioned, many people are often born with astigmatism, but in some cases, it can occur after an eye injury, operation or disease. This eye condition or refractive error is caused when your eye isn't completely round, meaning it looks more like a rugby ball than a football. If the shape of your cornea is irregular like this then the light is bent in more than one direction, so objects appear blurry and not fully in focus.

Astigmatism usually occurs alongside other refractive eye conditions like myopia (short-sightedness) and hyperopia (long-sightedness), which result in your eyes incorrectly bending light rays. The rare condition, keratoconus, can also alter the clear front part of your eye, making it more cone-shaped and causing astigmatism to occur. Contrary to popular belief, you can't develop or worsen astigmatism by sitting too close to your television or reading in poor lighting.

What is astigmatism?