What causes keratoconus?

Keratoconus is a hereditary condition of the cornea typically characterized by its being very thin, lacking radial symmetry, and/or shape instability. Any of these in combination can cause irregular vision that is not well-corrected with glasses or soft contact lenses.

Can it be caused by the mistakes during LASIK surgery?

A normal cornea can be made to look and behave like keratoconus if LASIK is performed on it inappropriately. An inappropriate cornea for LASIK or PRK would be one that is already more thin than normal, is irregular, or is made too thin by attempting to treat too high a nearsighted prescription. This is actually called "ectasia" but it is functionally about the same as keratoconus.