WASHINGTON — A decade after Lasik eye surgery hit the market, patients left with fuzzy instead of clear vision are airing their grievances before federal health officials.

Make no mistake: Most Lasik recipients do walk away with crisper vision, some better than 20/20.

But not everyone’s a good candidate, and an unlucky few do suffer life-changing side effects: poor vision, painful dry eyes, glare or problems seeing at night.

How big are the risks? The Food and Drug Administration thinks about 5 percent of patients are dissatisfied with Lasik. How many struggle daily with side effects? How many are just unhappy that they couldn’t completely ditch their glasses? The range of effects on patients’ quality of life is a big unknown.

So with a public hearing Friday, the FDA is beginning a new effort to determine if warnings about Lasik’s risks are appropriate. The agency also is pairing with eye surgeons for a major study expected to enroll hundreds of Lasik patients to better understand who has bad outcomes and exactly what their complaints are.

“Clearly there is a group who are not satisfied and do not get the kind of results they expect,” FDA medical device chief Dr. Daniel Schultz said Thursday. The study should “help us predict who those patients might be before they have the procedure.”

About 7.6 million Americans have undergone some form of laser vision correction, including the $2,000-per-eye Lasik. Lasik is quick and, if no problems occur, painless: Doctors cut a flap in the cornea — the clear covering of the eye— aim a laser underneath it and zap to reshape the cornea for sharper sight.

The vast majority of patients, 95 percent, see better and are happy they had Lasik, said Dr. Kerry Solomon of the Medical University of South Carolina, who led a review of Lasik’s safety for the American Society of Cataract and Refractive Surgery.

But doctors advise against Lasik for one in four people who seek the surgery. Their pupils may be too large or corneas too thin or they may have some other condition that can increase the risk of a poor outcome.

Solomon estimates that fewer than 1 percent of patients have severe complications that leave poor vision. Other side effects, however, are harder to pin down. Dry eye, for instance, can range from an annoyance to so severe that people suffer intense pain and need surgery to retain what little moisture their eyes form. That’s the kind of question the FDA’s new study is being designed to answer.

Dry eye is common even among people who never have eye surgery, and increases as people age. According to Solomon, 31 percent of Lasik patients have some degree of it before the surgery and that about 5 percent worsen afterward.