What is a laser? It’s a man-made light beam. There are many types and they’re named according to how they’re made, e.g.
· Gas lasers, such as the CO2 laser which is used in skin resurfacing
· Solid state lasers, such as the nd:YAG laser made with a ruby cylinder, which are the most powerful lasers, and
· Semiconductor lasers, which have less power and are used in laser printers, CD players, etc. Laser light is different from other kinds of light, such as headlights, flashlights, street lights, etc.
· It’s coherent – the light waves are parallel with each other and can travel far without spreading out like a flashlight
· It’s directional – because it’s coherent, it can be highly focused
· It’s monochromatic – it contains only one color, as opposed to white light which contains all colors. They can be within our visual range of color, infra-red, or ultra-violet
Lasers were first made in the 1950s, but not until the 1990s were they used for vision correction.
Excimer lasers
Excimer lasers are the type used by eye doctors. They’re a type of gas laser and their name is a contraction of “excited” and “dimer” (a “dimer” is a pseudo-molecule which gives off ultraviolet light when it’s in an excited state).
Excimers are non-thermal lasers. That means there’s no danger of any burn to the eye tissue. They’re used for PRK and LASIK procedures.
Photorefractive Keratectomy (PRK) Treatment
PRK was developed in the early 1980s but was not done in the U.S. until the FDA approved it in 1995. It uses an excimer laser to correct lower-order aberrations – near- and far-sightedness and astigmatism. This procedure is short. You’re positioned beneath the laser and a retainer is placed over your eye to keep it open. Your eye doctor uses anesthetic eye drops so you’ll feel no pain. He’ll remove a tiny amount of tissue from the surface of the eye, the cornea, and the laser will correct the exposed tissue, smoothing it to correct your vision. Wavefront-guided LASIK The remarkable advance of Wavefront-guided LASIK is that it can correct not only the lower-order aberrations, but also the higher-order aberrations like halos, glare and night vision trouble. The laser itself is part of an integrated workstation which includes a highly adjustable patient chair along with the microscope, computer, and controls of all kinds for your eye doctor to operate with. Both the mapping and the correction are done by this system. Wavefront mapping
As you lie back in the workstation chair, the excimer laser first does the mapping work. The light wave is sent through your iris to the retina at the back of the eye, from which it bounces back to a sensor. It carries information with it, based on what happened to it as it traveled through the eye’s cornea (outer surface).
From this information, the system makes a 3-D map of your eyeball, which will show your eye doctor what needs to be corrected. The system translates this information into mathematical formulae which your eye doctor will program into the computer that controls the laser beam. Vision correction
As you continue to lie back in the patient chair, your doctor proceeds with the laser correction. To direct the laser to the tissue immediately below the cornea’s surface, he cuts a thin flap of tissue and bends it back. The laser then removes tiny pieces of tissue that were affecting your vision, modifying the shape of your cornea. The tiny flap is replaced and heals by itself. Laser and doctor work together The precision of the laser and the education and skill of the doctor make a formidable team that plays on your side. Whether you have PRK treatment or Wavefront-guided LASIK, choose an experienced eye doctor and you can then be sure that he’ll use the laser expertly.
