Astigmatismus
Image distortion occurs for both near and far objects.
Astigmatism, a common condition, occurs when the curvature of the cornea is asymmetric.
A normal cornea is shaped spherically, similar to the lens of a camera. Horizontal as well as vertical lines are refracted to form a focused image. A dot-like source of light, such as a street light, will produce a dot-like image. But if the curvature of the cornea is elliptic instead of spherical light rays focus at different points causing image distortion. In our example, the street light will not produce the image of a bright dot but a small line.
Astigmatism occurs frequently in addition to nearsightedness or farsightedness.
Today, there are several surgical procedures available for astigmatism correction:
| Eye laser procedures | Astigmatism | |
| individual LASIK, Femto-LASIK | up to 5 dpt. | |
| PRK / LASEK | possible | |
| Lens procedures | ||
| Phakic lens implant (toric lenses) | possible | |
| Refractive lens exchange (toric lenses) |
possible | |
| Combination procedures | ||
| Bioptics | possible |