The microkeratome was first used in 1963 by Jose’ Barraquer, M.D. He performed keratomileusis using a keratome very similar to the one used today. The Excimer laser for use in the PRK procedure was investigated thoroughly by the FDA and there are over ten years of clinical experience with this laser.
With LASIK a thin flap is made with the microkeratome. This flap is “folded back” to expose the inner layer of the cornea. The Excimer laser is then used to reshape this layer. The Excimer laser is a “cold” laser that breaks up the molecular bond between cells and vaporizes them. Since it is a cold laser, the tissue next to the treatment area is not damaged. Then the flap is replaced and the eye is dried for several minutes to make sure that the flap is adhering and in place. The natural suction mechanism of the cornea keeps the two layers together as they heal. By changing the shape of the cornea, the light rays that enter the eye are focused more on the retina reducing nearsightedness, farsightedness and astigmatism.
Femtosecond (All-Laser LASIK)
LASIK utilizing a Femtosecond laser is commonly known as “all laser LASIK.” In this procedure, tiny direct pulses of infrared light are administered at a specific depth within the corneal surface. These light pulses separate the corneal tissue at the molecular level creating microscopic bubbles of carbon dioxide and water at their point of impact. The laser moves back and forth across the eye creating a pattern layer of the bubbles that becomes the back surface of the corneal flap and the underlying corneal tissue layer called the stromal bed. This entire flap creation process can between 25 to 45 seconds. Once the tissue pattern separation is complete, the surgeon will need to make sure all the tissue is completely separated before lifting the flap. In some cases the surgeon will need to work more cautiously to make sure the corneal flap is completely separated before lifting.