Can you tell me how are spherical abberations caused by lasik corrected?

Visual aberrations: The visual system has aberrations within it, whether or not a patient has had previous eye surgery. When correcting vision with LASIK, some patients may experience some visual aberrations that affect they quality of vision, but this is uncommon. If a patient does have some spherical aberration postop, this can be fixed with a wavefront-guided reshaping of the cornea and is very successful.