- The Washington Times - Monday, April 25, 2005

North Bethesda resident Glenn Merberg cannot tell the difference between the conventional LASIK surgery he had done in his left eye and the custom LASIK in his right.

LASIK, the common name for Laser-Assisted In-Situ Keratomileusis, is a procedure that uses lasers to repair optical abnormalities in the eye. Custom LASIK uses a wave-front analyzer, a piece of equipment that measures abnormalities in the eye, to generate an individualized or customized map of the eye before the surgical process begins.

Mr. Merberg, 39, was not eligible for custom LASIK in his left eye, which, in February 2004, measured at too high a diaptor, a measurement for a refractive error, for Food & Drug Administration approval. Refractive refers to how the eye bends light in order to see, and refractive error to bending light incorrectly.

“I couldn’t wear my contacts all day. They would be uncomfortable and scratchy,” says Mr. Merberg, who works as a computer consultant. “If I could have worn my contacts, I would have worn them forever.”

Mr. Merberg, who wore contacts for 25 years, waited to have surgery, he says. With surgery, his vision improved to 20-15.

“We now, on a daily basis, can improve people to a level of acuity never experienced in the past,” says Dr. Thomas Clinch, consultant in corneal, cataract and refractive surgery at University Ophthalmic Consultants of Washington, which has offices in Chevy Chase and Northwest.

Custom or wave-front-guided LASIK, approved by the FDA in May 2003, provides better results than conventional LASIK, allowing a higher percentage of patients to leave the operating room with 20-20 vision or better, metro-area ophthalmologists say. The procedure involves taking several measurements of the eye and making individualized surgical corrections. LASIK, performed since 1996, is a type of refractive surgery.

“You end up getting a treatment that is customized to the shape of your cornea,” says John Ciccone, spokesman for the American Society of Cataract and Refractive Surgery, a medical specialty organization based in Fairfax.

Custom LASIK is 25 times more accurate in measuring aberrations, or visual imperfections, in the eye than conventional methods, Mr. Ciccone says.

Ninety-four percent of custom LASIK patients achieve 20-20 vision or better, compared to 68 percent of conventional LASIK patients, according to the FDA.

“Their experience is similar for conventional and custom LASIK, but the results are better for custom,” says Dr. Allan Rutzen, a Fellow of the American College of Surgeons (FACS) and co-director of the University Laser Vision Center at the University of Maryland in Baltimore.

Conventional LASIK measures lower-order aberrations or refractive errors through tests similar to those for fitting eyeglasses and contacts. Lower-order aberrations include myopia or nearsightedness, hyperopia or farsightedness, and astigmatism.

Alternatively, custom LASIK includes higher-order aberrations, suspected of causing visual glare and halos and affecting night vision. Higher-order aberrations, irregularities other than refractive errors, often do not affect vision.

Higher-order aberrations account for 10 percent to 20 percent of visual distortions in the normal eye, says Dr. Robert A. Copeland Jr., chairman of the Department of Ophthalmology at Howard University in Northwest.

“We all have it,” Dr. Copeland says. “We have certain aberrations of the eye.”

A wave-front analyzer — a device with a chin rest, hood and screen — is used to measure higher-order aberrations. The device shines hundreds of laser beams to different spots on the cornea in a few milliseconds, says Dr. Edward Perraut, medical director of the TLC Laser Eye Centers in Fairfax, with offices in Reston and Rockville and originally called the Laser Center (TLC). The analyzer measures how the light beams are distorted, or out of focus, as the eye reflects the beams back out.

“The imperfections cause the light to bend, to come out in a different angle or come out slower or faster,” Dr. Perraut says.

The imperfections are analyzed by computer to produce a customized map, which looks like a topographical map.

“It generates a map as unique to your eye as your fingerprint,” Dr. Perraut says. “That’s the information that drives the software that drives the laser. It’s customized to your eye, so no two treatments are the same.”

The surgical procedure is the same for both custom and conventional LASIK. A surgical instrument, either a microkeratome blade or an IntraLase laser, is used to create a flap on the cornea, a superficial layer of tissue in front of the iris. IntraLase places tiny bubbles that, as they expand, lift the tissue, making a continuous incision.

An excimer laser, an ultraviolet laser, is used to ablate, or reshape, the cornea by removing tissue. The excimer is equipped with a tracker that locks onto the pupil to track its movement and to place the laser beam precisely. The laser beam is applied to the bed, the exposed area of the cornea, to remove tissue that causes the distortions in vision.

The cornea in myopia is too steep, so the laser flattens the center of the cornea. In hyperopia, the cornea is too flat, and the laser removes tissue in the periphery to steepen the eye. The cornea in astigmatism is asymmetrical, steeper in one meridian and flatter in another.

Once excess tissue is removed, the flap is replaced.

“Some of the healing goes on for three months, but 95 percent of the improvement goes on overnight,” Dr. Perraut says.

Side effects can include dry eyes, the most common complaint and also a minor one; complications with healing of the flap; and infections, which are rare, Dr. Copeland says.

Two percent to 3 percent of patients of custom LASIK need touch-up work or minor enhancements following surgery, Dr. Clinch says.

“People think this is a once-in-a-lifetime procedure, but it’s not,” he says, adding that if patients’ eyes change over time, they can have an enhancement to rectify the change.

Patients are required to have a stable prescription, a cornea thick enough for flap removal and to be free of diseases that could affect healing, such as severe cases of autoimmune diseases and certain eye diseases including glaucoma, cataracts and macular degeneration, Dr. Perraut says.

The prescription needs to be within a certain range, up to -12.00 diopters for myopia, up to +6.00 diopters for hyperopia and up to -6.00 diopters for astigmatism, he says.

“So many people who have been told in the past they were not good candidates now can safely reduce or eliminate their need for contacts or glasses,” says Dr. Roy Rubinfeld, surgeon for Washington Eye Physicians and Surgeons in Chevy Chase and clinical correspondent for the American Academy of Ophthalmology, an eye doctor association based in San Francisco.

Custom LASIK costs about $2,500 per eye from top-level surgeons, he says.

The price ranges from $1,800 to $2,500 for conventional LASIK and costs another $200 or more per eye for custom LASIK, Dr. Perraut says.

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