Patients suffering from astigmatism do not have evenly round corneas, rather corneas with various curvatures (bumps and dips) in different directions.
There is a difference between genetic regular and irregular astigmatism. The latter can also be caused by eye disorders, such as inflammation of the cornea or cataracts.
Image: Irregularities on the cornea (marked left) prevent a sharp image of the environment on the retina (marked right).
The malformed cornea leads to irregularities in the refractive power of the eye, as a result of which points become lines when looking at objects.
Images and objects look more or less warped to the viewer. The world seems blurred.