LASIK involves shaving off some of the substance & reshaping it. It can be repeated until the corneal thickness & shape allow such manipulation. Regarding risks - Each procedure of LASIK therefore thins the cornea & there is a threshold beyond which it could be dangerous. It can also can induce anomalies called "ocular aberrations" which reduce the quality of vision. The costs can vary between different surgeons, but the thing to understand here is that the expectations of vision improvement are quite modest.

Hello Usually once but resurgery can be planned if corneal parameters permit