Advertising stresses the surgery's safety, and most procedures are successful. Tiger Woods, who relies on keen eyesight as the world's best golfer, pitches it as a quick and painless way to restore sharp vision. Even the U.S. Air Force, long skeptical of the surgery, changed its policy in May to let people who had LASIK apply for pilot training.

But every year thousands of Americans who undergo LASIK are left with chronic pain, dryness of the eyes, distorted night vision and even blindness, according to Food and Drug Administration statistics.

LASIK -- which stands for laser-assisted in-situ keratomileusis -- uses lasers to cut and reshape the cornea. It can improve eyesight without complications, but equipment flaws, a surgeon's error or a failure to screen out patients whose eyes are ill-suited for the treatment can cause the operation to go awry.

The American Society of Cataract and Refractive Surgery, which represents about 9,000 ophthalmologists specializing in laser eye surgery, estimates that only 2 percent to 3 percent of the more than 1 million LASIK surgeries each year are unsuccessful. But Food and Drug Administration records of clinical studies show that six months after the surgery, up to 28 percent of patients complained of eye dryness, up to 16 percent had blurry vision and up to 18 percent had difficulty driving at night.

The Triangle, home to two medical schools, is a hot spot for LASIK; 11 eye centers will perform LASIK on about 8,000 patients this year, according to market research.

One of the leaders is Duke Eye Center, whose LASIK surgeons are among the best-trained and best-equipped in the field. But even surgery at Duke's level has damaged a few patients' eyes beyond repair.

One of those patients is Matthew Kotsovolos, 38, of Raleigh. He was the Duke Eye Center's head of finances and received the surgery for free June 8, 2006. It gave him 20-20 vision but left him with intensely dry eyes and excruciating facial pain. He wakes up with sore eyes every morning, wears special goggles to preserve eye moisture and wonders when the pain in his face will kick in.

"I traded in my glasses for permanent head pain, eye pain and these things," Kotsovolos said, pointing to the goggles.

Nine months after his surgery, Kotsovolos quit his job at the Duke Eye Center, took a 25 percent pay cut and started work as business manager in the Duke University Medical Center's gastroenterology division. He is organizing a support group for LASIK patients with complications.

"It may help inform people that this is a surgery with real risks that are understated by LASIK surgeons," Kotsovolos said.

Alan Carlson, head of the Duke Eye Center, said his experience with LASIK is that complications are rare. Carlson, who did not operate on Kotsovolos, said only a handful of the roughly 6,000 LASIK patients he has treated at Duke since 1996 ended up with problems. The eye center does very well in patient satisfaction surveys, he said.

But Carlson acknowledged that the procedure can cause serious complications.

"It's imperfect surgery in an imperfect world," he said.

How many LASIK patients develop post-surgery complications is obscured by a lack of regulation and reporting. Because health insurers don't pay for LASIK, they generally don't track complications. The FDA doesn't require reports from doctors, and regulatory enforcement has been largely limited to recalling malfunctioning lasers.

Post-LASIK lenses

Evidence of problems is accumulating. Some of the strongest is the growing market for contact lenses designed for people who have undergone LASIK and still have vision problems, some seeing worse than before the surgery. One of the leading post-LASIK lens makers is MedLens Innovations, a Front Royal, Va., company founded in 2000.

Robert Breece, an optometrist and MedLens' president, said his company provides hard contacts to more than 2,500 post-LASIK patients annually and business is increasing about 10 percent every year. Breece said his company serves more than 200 people per year who have been seriously disabled by the surgery.

"I don't get to talk to happy LASIK patients," he said.

By the end of the year, SynergEyes of Carlsbad, Calif., plans to bring to market the first line of contact lenses designed specially for laser eye surgery patients with complications who cannot tolerate hard lenses.

A trial version of the SynergEyes contact lenses have given Paula Cofer, 49, of Tampa, Fla., some relief from dry, itchy eyes and night vision so distorted that she sees up to eight moons.

The specially fitted contacts cost $300 every six months, Cofer said. Contact lenses solution, sterile saline solution, artificial tears and lenses rewetting drops run another $150 to $160 per month.

"Life was very simple then," she said about the 30 years she wore glasses. "Now, it's very complicated."

Limitations of LASIK

Patients with complications are starting to fight back on the Internet and through support groups. Medical research in the past three years has come up with insights about LASIK worrisome enough that some eye surgeons have begun to ease away from the procedure.

"We've learned the limitations of LASIK," said Dr. Stephen Pflugfelder, professor of ophthalmology at Baylor College of Medicine in Houston.

An expert in laser eye surgery for more than 15 years, Pflugfelder is increasingly falling back on an older, less invasive procedure known as photorefractive keratectomy, or PRK, which involves only the surface of the eye.

In the past three years, the number of LASIK procedures at Baylor has dropped from about 70 percent to about 50 percent of all laser eye surgeries.

At Duke, LASIK makes up about 80 percent of all laser eye surgeries. Carlson, head of the Duke Eye Center, is comfortable with that.

"Dry eye hasn't been a big problem," he said.

The university buys the most sophisticated lasers on the market, he said. Patients are screened for risk factors and informed of what they can and cannot expect from LASIK. A surgeon might even do the surgery on one eye at a time.

Those precautions did not prevent Lauranell Burch, a former Duke medical researcher, from suffering a serious complications after undergoing LASIK at the Duke Eye Center.

Burch 47, said that since the surgery March 31, 2004, her eyes sting and burn all the time, her eye tissue is wrinkled like a Ruffles potato chip and her night vision is distorted.

"[The damage] is noticeable and on the front of your mind all your waking hours," Burch said. "There's no escape."

In the winter, she takes an anti-anxiety pill about 15 minutes before she drives home in the dark from her job in Research Triangle Park. She compares the distortions she sees at night, also known as star bursts, to explosions of light without a bang.

Burch cut short her follow-up treatment at Duke, became an avid patients' advocate and started to take on LASIK surgeons on the Internet.

Risks of high volume

All LASIK surgeons make an effort to screen patients, and many turn away patients with obvious risk factors.

But LASIK is essentially a buyer-beware procedure.

In choosing a surgeon, patients are usually advised to go with doctors who perform the procedure most frequently. But with LASIK, that advice can be risky.

Dr. Christopher Fleming, a Cary ophthalmologist and former president of the N.C. Society of Eye Physicians and Surgeons, said patients should beware of LASIK surgeons who perform a high volume of operations.

Surgeons who do 10 or 15 LASIK operations a week tend to contract with optometrists who refer patients, Fleming said. In return, the optometrists, who are not medical doctors, screen the patients and do the follow-up care. Some also receive referral fees.

The emphasis on volume, Fleming said, can draw patients into surgery whose eyes are not suited to LASIK. Patients also end up getting follow-up care from optometrists instead of their surgeons.

Fleming performs no more than one or two dozen LASIK surgeries a year and personally screens patients and does the follow-up care. As a result, his patients rarely have complications, he said.

"When you're high-volume and relinquish part of the care to non-physicians," Fleming said, "you don't have time to be thorough. That can lead to problems."

What deters lawsuits

How many North Carolinians have problems after LASIK is not a public record. Patient complaints filed with the N.C. Medical Board are confidential, and the data are not organized by medical procedure.

Only a few complaints become lawsuits, said Bill Faison, a well-known medical malpractice lawyer in Durham who has represented one LASIK patient in court in the past three years.

What foils most attempts to sue for damages, Faison said, are the costs to mount a legal challenge. Also, carefully worded patient consent forms spell out the risks of the surgery and often require patients to first try to work out their differences with the LASIK center.

"Short of the [LASIK surgeon] being stupid, if it's just a bad outcome, there's nothing to recover," Faison said.

The procedure is safe and effective for many, said Dr. Brad Randleman, a laser eye surgeon at Emory University in Atlanta who has done LASIK on about 1,000 patients over the past five years.

Post-surgical complications such as dry eyes and vision distortions often subside after a few weeks.

"I had nothing but a great experience," said Jim Branch, 55, a Raleigh real estate developer who had LASIK at Duke about five years ago.

Medical research has found that cutting the cornea permanently weakens it. The severed nerves need years to recover and might misfire pain signals. But those findings have not been conclusively linked to lingering complications from LASIK, said Dr. William Bourne, an ophthalmology professor and LASIK surgeon at the Mayo Clinic in Rochester, Minn.

"I don't think we've proven what it is," Bourne said.

A better understanding of what causes the complications is essential to screen patients more effectively and eliminate those at risk, he said.

Kotsovolos said he was considered a good candidate for LASIK. His Duke LASIK surgeon blamed part of his problems on an eye inflammation unrelated to the procedure. Another eye specialist has since diagnosed Kotsovolos with a severe dysfunction of the glands lining the eyelids. The condition is considered a red flag when it is found during screening for LASIK.

Charles Hybarger, a building contractor who lives near Chattanooga, Tenn., changed his mind about LASIK after his wife, Kim, a 44-year-old trained nurse, had an unsuccessful procedure Dec. 21 and the complications triggered a deep depression.

Hybarger wonders whether his wife's rheumatoid arthritis should have eliminated her from having LASIK. Laser eye surgery should not be done on patients with auto-immune diseases.

"I wouldn't let any doctor cut on me unless it's life or death," Hybarger said. "I just wear my glasses and be happy with it."

(News researcher Denise Jones contributed to this report.)