Vision Correction

Laser Vision Correction

Laser Vision Correction is a family of procedures predominated by LASIK (laser-assisted in situ keratomileusis), both traditional and wave-front guided, and PRK (photorefractive keratectomy).

LASIK

LASIK (laser-assisted in situ keratomileusis). A type of refractive surgery for correcting myopia, hyperopia, and astigmatism. LASIK is performed by ophthalmologists using a laser under a corneal flap. LASIK is similar to other surgical corrective procedures such as photorefractive keratectomy PRK though it provides benefits such as faster patient recovery. . A computer system tracks the patient's eye position thousands of times per second, redirecting laser pulses for precise placement.

Wavefront-guided LASIK

Wavefront-guided LASIK. A customized variation of LASIK surgery in which, rather than applying a simple correction of focusing power to the cornea (as in traditional LASIK), an ophthalmologist applies a spatially varying correction, guiding the computer-controlled Excimer laser with measurements from a wavefront sensor. The goal is to achieve a more optically perfect eye. Many patients are generally more satisfied with this technique than with previous methods, particularly regarding lowered incidence of "halos". Based on their experience, the United States Air Force has described customized Lasik as giving "superior vision results". Zyoptics is the customized approach used in a Bausch & Lomb Technolas Perfect Vision excimer laser.

PRK (Photorefractive Keratectomy)

Photorefractive Keratectomy (PRK). A laser eye surgery procedure intended to correct a person's vision, reducing dependency on glasses or contact lenses. PRK permanently changes the shape of the cornea using an excimer laser to ablate (remove by vaporization) a small amount of tissue from the cornea at the front of the eye, just under the corneal epithelium. The outer layer of the cornea is removed prior to the ablation.

The outer layer of the cornea, or epithelium, is a soft, rapidly regrowing layer in contact with the tear film that can completely replace itself within a few days. The deeper layers of the cornea, as opposed to the outer epithelium, are laid down early in life and have very limited regenerative capacity. The deeper layers, if reshaped by a laser or cut by a microkeratome, will remain that way permanently with only limited healing or remodelling. With PRK, the corneal epithelium is removed and the cells to re-grow after the surgery. The procedure is distinct from LASIK (Laser-Assisted in-Situ Keratomileusis), where a permanent flap is created in the deeper layers of the cornea.