Laser surgery techniques for refractive vision correction were well established, both scientifically and clinically, by the mid-80s. The basic principle behind all the methods is using a laser to model the outer corneal layer so that the focal point of the bundled incidental light is on the surface of the retina itself and not in front of or behind it. The original treatment methods, PRK and LASEK, manually removed the outer protective layer (epithelium) of the cornea before the laser surgery. The consequences often included post-operative pain and Laser surgery techniques, which involves a corneal flap (LASIK and Femto-LASIK) were then developed. Here, a mechanical cutting tool (microkeratome) or a femtosecond laser is used to create a thin flap of cornea which is just 120 micrometers thick. Almost a complete circle (270°) is cut in the upper layers of the cornea. The flap is then folded back like the cover of a book. Subsequently, the exposed corneal tissue is then ablated using an excimer laser in a separate stage of treatment. The greater the level of vision defect, the more tissue needs to be removed.
In the final stage of treatment, the corneal flap is then folded back into its original position. It then adheres in the original place over the coming weeks and months. The disadvantage is that the flap can shift or even tear off (flap displacement) as the result of rubbing or other physical contact after the operation. The ReLEx® SMILE principle: The high-precision VisuMax® femtosecond laser creates a small lens (lenticule) inside the intact cornea, the volume and form of which are determined by the degree of vision defect to be corrected. This lenticule is then removed in a minimally invasive procedure from the interior of the cornea through a small access measuring just a few millimetres. In contrast to earlier techniques, it is no longer necessary to fold back the cornea. There is no flap incision, the area of the incision is reduced to a minimum and the outer corneal layers remain more or less intact. All of which is made possible by a sensitive, precise and convenient treatment method.
Step 1: In a single step the VisuMax femtosecond laser creates a thin lenticule and a small access measuring less than 4 mm in the intact cornea.
Step 2: The surgeon removes the lenticule through the small access. There is minimal disruption to the biomechanics of the cornea. No flap needs to be cut.
Step 3: The minimally invasive removal of the lenticule changes the shape of the cornea, correcting the refractive error of the eye.
Step 1: The femtosecond laser creates a corneal flap.
Step 2: The patient is moved to the excicmer laser.
Step 3: The surgeon opens the flap and folds it back to expose the lower corneal layer (stroma) beneath.
Step 4: The excimer laser ablates the pre-calculated amount of corneal tissue, point by point.
Step 5: After the laser surgery is compled, the flap is returned to its original position. It then adheres in the original place over time.
Step 1: The patient is moved to the excicmer laser.
Step 2: The outer surface of the cornea”epithelium” is removed and discarded.
Step 3: The excimer laser ablates the pre-calculated amount of corneal tissue, point by point