These ocular conditions called "errors of refraction" (see section on "eye anomalies") can be corrected by 2 laser techniques: PRK and LASIK (95% of cases).
The principle is the same for both techniques: the excimer laser sculpts the cornea to change its shape (curvature). To correct myopia, the cornea is flattened. For hyperopia, the cornea is steepened. For astigmatism, the cornea is flattened along one axis, and steepened along the other.