In nearsighted patients, an invisible beam of laser light then trimmed away layers of tissue from the center of the cornea, producing a flatter curve. In farsighted patients, the beam scooped out a doughnut-shaped ring that resulted in a steeper curve. Then the doctors lifted the flap back into place. After a few minutes of drying, it rebonded with the rest of the cornea. Because tissue destruction is minimal, there's little healing and much less pain.
Patients see clearly almost immediately after the operation.
Provided the surgery is successful, of course. There is always a tiny risk of infection. Or the surgeon could accidentally slice off the corneal flap entirely, or replace it in such a way that it develops wrinkles. Imagine trying to see through crinkled Saran Wrap, and you get an idea of what can happen if something goes wrong. In the worst cases, as in Assennata's, the aberrations are so extensive that they cannot be corrected, even with glasses.