LASER EYE SURGERY

Purpose of LASIK

The purpose of LASIK is to improve vision and thus reduce a person's dependency on glasses or contact lenses. The LASIK procedure permanently changes the shape of the cornea, the clear covering of the front of the eye.

History of LASIK

LASIK stands for Laser Assisted In-Situ Keratomileusis. "Keratomileusis" is derived from two Greek words that literally mean "to shape the cornea." "In'-Situ" means "in place." Thus, the term LASIK means "to reshape the cornea in place using laser."

The LASIK procedure is the combination of two sophisticated techniques of surgery with the purpose of correcting refractive errors. The first technique uses a knife, called a microkeratome, to cut a thin layer in the cornea, leaving a hinge at one end of the flap. The flap is folded back to reveal the middle section of the cornea, called the stroma, the area to be sculpted by the laser. Cutting a flap allows for a rapid recovery of vision and reduces discomfort after surgery. The second technique uses pulses from a computer controlled Excimer laser (a cold, invisible, ultraviolet laser) to sculpt the underlying cornea by vaporizing a portion of the stroma and correcting the refractive error. Then the flap is replaced.

Before the first LASIK surgery was performed in 1991, earlier techniques of refractive surgery to reshape the cornea were used. The most important procedures were Radial Keratotomy (RK) and Photorefractive Keratectomy (PRK). The evolution of LASIK occurred in the search for a better form of refractive surgery to eliminate some of the limitations, risks, and complications of these earlier techniques.

Radial Keratotomy (RK)

The first practical application of Radial Keratotomy (RK) resulted from the occurrence of an eye accident. In the 1970's, Dr. Fyodorov of Russia was treating a boy whose glasses had broken and cut his cornea. When the boy's eyes had recovered, his refraction was significantly less myopic than it was before the injury. Dr. Fyodorov researched past efforts in refractive surgery and eventually worked out a more predictable formula for refractive surgery.

The Radial Keratotomy (RK) procedure involves using a series of peripheral cuts (incisions) radiating from the central cornea, with the result of flattening the central cornea. RK can only correct low degrees of myopia and astigmatism. In 1978, American ophthalmologists became interested in Dry. Fyodorov's findings. After visiting Dry. Fyodorov in Russia, Dr. Leo Bores brought the technology back to the United States.

Excimer Laser

The Excimer laser was patented for vision correction by Dr. Steven Trokel. The Excimer laser produces a high-energy, cold, ultraviolet light beam in pulses and delivers the pulses to the surface of the eye's cornea. These pulses break the bond between molecules and tissue cells to that a controlled amount of tissue can literally be vaporized away to reshape the cornea, one microscopic layer at a time. The Excimer laser is computer controlled and programmed to custom treat each individual eye with a high degree of precision.

The Excimer Laser was originally used for etching silicone computer chips in the 1970's. Working in the IBM research laboratories in 1982, Dr. Rangaswamy Srinivasin, James Wynne, and Samuel Blum, saw the potential of the Excimer laser in interacting with biological tissue, discovering they could remove tissue with a laser without causing any heat damage to the surrounding material. Dr. Steven Trokel, a New York City ophthalmologist, made the connection to the cornea and performed the first laser surgery on a patient's eyes in 1987. Over the next ten years, the techniques and equipment for laser eye surgery were perfected. In 1996, the first Excimer laser for refractive surgery was approved in the United States. The Excimer laser has an international track record for safety and effectiveness.

Photorefractive Keratectomy (PRK)

Photorefractive Keratectomy (PRK) was the first surgical procedure developed to reshape the cornea using a laser. In PRK, the top layer of the cornea, called the epithelium, is scraped away to expose the stroma layer underneath. Because there are nerve fibers in the epithelium, there may be some initial discomfort equivalent to a badly scratched eye. This can further cause pain, irritation, watering of the eye, blurry vision, or the feeling of a particle in the eye. An eye bandage is worn to reduce the irritation and encourage healing of the tissue. Following PRK, vision is blurry for a few days, but improves as the corneal epithelium heals. Vision is often reasonably good at one week and stabilized by six months.

LASIK

LASIK evolved from PRK and both surgeries use an Excimer laser in a similar manner. The major difference between the two surgeries is the way that the stroma, the middle layer of the cornea, is exposed before it is vaporized with the laser. In LASIK, a flap is cut in the stroma layer, which is folded back for the surgery, then replaced after the use of the laser. Since LASIK does not disturb the sensitive top layer of the cornea there is less discomfort and a faster recovery than with PRK, and the visual benefits are the same.

LASIK surgery was developed in 1990 by Dr. Lucio Buratto (Italy) and Dr. Ionnis Pallikaris (Greece), combining two known surgical procedures, Keratomileusis and Photorefractive Keratectomy. They were the first to use a microkeratome to cut a thin flap of cornea and then apply the Excimer laser to remove tissue from the cornea. The microkeratome had been used successfully in South America for about 30 years, but had not been used in combination with the laser. It was Dr. Pallikaris that suggested the name Laser In-Situ Keratomileusis (LASIK) for this procedure. In 1991, Dr. Stephen Slade performed the first LASIK procedure in the United States.

LASIK is now the most commonly performed refractive surgery procedure.