What does 'flap' mean in laser eye surgery?

During an IntraLASIK treatment, the doctor makes a so-called flap. The cornea consists of six thin layers of tissue. With a flap, the doctor uses the laser to loosen three layers of the cornea. The opening has a length of about 20 mm and the shape of a horseshoe. Then the flap is turned, like a page, so that the laser can treat the exposed tissue.

The flap is made with the VisuMax laser. This super-fast laser sends short infrared pulses to the cornea with high precision. This creates small gas bubbles in the cornea. Within a few minutes, these gas bubbles form a kind of interspace that protects the surrounding tissue, as it were. This allows the surgeon to use the laser to create a very thin flap without damaging other tissue.