A normal eye is spherical, like a football.
Astigmatism occurs when your eye is more oval-shaped (like a rugby ball), meaning that the curvature of the cornea (the transparent covering at the front of the eye) is not the same horizontally as it is vertically.
The result of this is that, when light enters the eye, it is focused at two different planes rather than at a single point.
Images appear blurred or distorted, and you may experience ‘ghosting’. Approximately half of all people with myopia or hyperopia have some astigmatism as well.
Laser eye surgery can correct astigmatism, whether it is accompanied by myopia or hyperopia, or present alone.