LASIK 101: Procedures, Risks, and Benefits

LASIK, which stands for laser-assisted in situ keratomileusis, evolved from the excimer laser. Columbia University researcher and ophthalmologist Stephen Trokel borrowed one in the 1970s to perform laser vision correction. In 1988, Trokel and his colleague Marguerite McDonald performed the first photorefractive keratectomy (PRK) procedure on a women with malignant melanoma who had a growing black spot in her eye. The U.S. Food and Drug Administration (FDA) approved the first excimer laser for the use of the PRK to correct nearsightedness in December 1995.

In 1990, two European eye doctors improved PRK by developing what was dubbed the “flap and zap” technique, an early form of LASIK. Instead of working on top of the corneal surface, they used a blade to cut a thin flap in the cornea, zapped the tissue underneath, and reused the flap as a natural bandage. This groundbreaking method was more comfortable, led to faster recovery, and did not require stitches. The Kremer Excimer Laser System was the first to be approved for the use of LASIK in July 1998. Since then, more than 30 different laser systems have been approved by the FDA.

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Star S4 LASIK Machine

How is LASIK Surgery Performed?

Today, LASIK is the most commonly performed laser eye surgery to treat myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. More than 6000,000 people in the U.S. undergo LASIK surgery every year. An extremely precise, high-tech laser is used to carefully reshape the cornea’s focusing power. For myopia, a cornea that is too steep is flattened. For hyperopia, the laser is used to form a steeper cornea. To correct astigmatism, the laser transforms an irregularly-shaped cornea into a more normal shape.

In an outpatient suite, the patient reclines under the excimer laser and the eye is numbed with a few drops of topical anesthetic. An eyelid holder is placed between the eyelids to keep them open and prevent blinking. A suction ring is placed on the eye to flatten the cornea, and also helps prevent the eye from moving. The pressure from the eyelid holder and suction ring feels similar to a finger pressed firmly on the eyelid. During surgery, the patient’s vision dims or is completely dark. After the cornea is flattened, a hinged flap of corneal tissue is created using a precision laser or blade. The corneal flap is lifted and folded back. The patient’s unique eye measurements are preprogrammed into the excimer laser. The laser is placed over the center of the eye. While the patient looks at a pinpoint fixation or target light, the excimer laser sculpts the corneal tissue. The flap is put back into place and the edges are smoothed. Within 2-5 minutes, the corneal flap adheres to the underlying corneal tissue, so stitches aren’t required.

Current LASIK Procedures

Many eye doctors use computerized imagery called wavefront technology to create a highly sophisticated image of the cornea as a guide. The following are the most common procedures.

PRK: This is used to correct mild to moderate myopia, hyperopia, or astigmatism. Only the surface of the cornea is reshaped, not the tissue underneath, so this approach does not use a flap.

LASEK (laser epithelial keratomileusis): This procedure is similar to PRK and treats the same conditions. A flap is created, tissues are loosened with an alcohol solution, and the cornea is reshaped with the laser. The difference is a soft contact lens is used to hold the flap in place while the eye heals.

epi-LASIK: A thinner flap is created than the one used in LASIK, which benefits patients with thinner than normal corneas. During this procedure, the flap is separated from the underlying corneal layer with an epithelial separator. This tool has an oscillating plastic blade with a thin blunt edge. Alcohol solution is not applied to loosen tissue. The remaining steps mirror LASIK.

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Risks of LASIK

Although improvements have been made in LASIK techniques, like all surgeries, there are potential risks and complications. The overall complication rate is low, however, a small number of patients may have worse eyesight after surgery, even with eyeglasses or contacts. If infection or inflammation occur, medication usually resolves this, although other treatment may be required. Corneal flap problems affect only 0.5% of patients who undergo Bladeless LASIK with a femtosecond laser. Additional treatment is required to address flap complications. The following side effects are usually fleeting, but in a small percentage of patients, they can be permanent.

  •    Glare
  •    Light sensitivity
  •    Scratchiness
  •    Discomfort or pain
  •    Hazy or blurry vision
  •    Halos or starbursts around lights
  •    Difficulty with night vision and/or driving at night
  •    Dryness and others symptoms of dry eye
  •    Small pink or red patches on the white of the eye
  •    Epithelial ingrowth (healing corneal tissue growing under the flap)
  •    Regression of vision correction over time

Benefits of LASIK

It can take 3-6 months to assess the benefits of LASIK because vision has to stabilize post-surgery. An estimated 95% of patients achieve vision of 20/40 or better, while 85% regain 20/20 vision. Additional benefits include:

  •    Evidence-based, proven technology
  •    Relatively painless, quick outpatient surgery
  •    No need for stitches or bandages (in most cases)
  •    Dramatic reduction in need for eyeglasses or contacts
  •    Long-term cost savings after initial investment
  •    Adjustments can be made years later to further correct vision

Not everyone is a suitable candidate for LASIK. People with eye diseases, herpes simplex affecting the eye area, other eye infections, eye injuries, and large pupils should not have LASIK. It is also contraindicated in people with severe refractive errors and for presbyopia (age-related changes requiring reading glasses). On the other side of the equation, if you have fairly good vision with a minimal refractive correction, the risks of surgery typically outweigh the cost and benefits. Moreover, people involved in facial contact sports (e.g. martial arts or boxing) should also not undergo this surgery.

To learn more about your eyes, read our latest blog on changes in your eyeglasses prescription by our Optometry Advisory member, Dr. Careen Caputo HERE.