Laser eye surgery: the procedure
The surgery consists of three phases: the first is preparatory.
During this first phase, as with PRK (another operation used to treat slight to moderate myopia, associated or not with mild astigmatism), an anaesthetic eyewash is applied to the eye to make the part to be treated absolutely insensitive to pain. This type of "topical" anaesthesia is advantageous because it makes the surgery painless throughout the entire procedure. Nonetheless, on occasion, after the surgery, patients may experience mild discomfort or the sensation of a foreign body in their eye, as also occurs with PRK. This is well tolerated and disappears within a few days.
The second phase involves the operation itself: having anaesthetized the part in question, a precise view of the area to be cut is observed through the aberrometer, an instrument that detects even the smallest defect in the eyes to be subjected to the laser surgery. Then, using an instrument called a "microkeratome" or femtosecond laser, a cut on the cornea, called a "lamellar cut", is made. This involves cutting a superficial circular flap of the cornea to a diameter of 9 mm and to a depth of about 25% of the total thickness. This flap is then folded and opened like the page of a book.
Now the third phase can begin; the actual treatment on the inside of the exposed cornea using the excimer laser. It is later closed without any sutures (stitches). During this phase – the most important in the entire procedure – the curvature of the cornea is modified to correct the vision defect, whether it is myopia, hyperopia or astigmatism.
The laser receives data regarding the vision defects to be corrected directly from the aberrometer whose precision enables it to detect even the tiniest defect. It aims the excimer laser in the right direction to rectify these defects.
If the surgery does not achieve a sufficient degree of correction, the treatment can be repeated after no less than 3 months.