Laser eye surgery has enabled millions of people to throw away their eyeglasses. Now several medical technology companies are hoping that lasers aimed at the feet will allow millions to take their socks off, even in public.

The target is toenail fungus — an infection in an estimated 10 percent of American adults, or 23 million people — that causes toenails to become thick, yellow and fetid.

If these lasers, which recently completed small clinical trials, work, they will represent a new way to treat nail infection by selectively irradiating fungi while leaving the nail and surrounding tissue intact.

Right now, there is no sure cure. The fungi are so hardy that popular antifungal pills, which carry a small risk of liver damage, are completely successful less than half of the time. And a prescription lacquer, painted on the toenails daily for 48 weeks, has a complete cure rate of less than 10 percent.

Pharmaceutical giants like Schering-Plough and Novartis are developing new lacquers, pills and ointments to battle the fungi. But some podiatrists and patients are pinning their hopes on the experimental laser treatments.

Nomir Medical Technologies in Waltham, Mass., is developing a laser called Noveon for diseases like antibiotic-resistant staph infections as well as nail afflictions.

Noveon is a type of laser already commonly used by doctors for treatments like cataract surgery, dental work and even hair removal. Noveon beams two different wavelengths of near-infrared light at toenails to selectively take aim at and kill fungi.

After four treatments with Noveon, about half of the 39 toenails tested no longer had active nail infections, according to the results of a clinical trial that the company presented this month at a national dermatology meeting. Six months after the initial treatment, about 76 percent of the volunteers had clear nail growth, the study reported.

"We will be able to reach people who have heretofore stayed away from treatment because of the toxicity or the costs or other reasons," said Richard F. Burtt, Nomir’s chief executive.

Mr. Burtt said the company was preparing to submit the data to the Food and Drug Administration, hoping to receive clearance to market Noveon by this fall. The agency has already cleared Noveon for use on the skin and in nasal passages. But the company is not taking orders for or distributing the laser for nails until it receives specific permission to do so, Mr. Burtt said.

Another company developing a laser, PathoLase, is so eager to get a piece of the billion-dollar-plus market for antifungal nail treatments that it has not waited for federal permission to begin marketing its device, the PinPointe Footlaser, for use on toenail fungus. Nearly 70 podiatrists in 21 states already offer PinPointe, according to PathoLase. The treatment, which is not covered by health insurance, costs $1,000 or more.

The F.D.A. requires manufacturers to wait for federal clearance before marketing a medical device for specific uses. But PathoLase appears to have jumped the gun in the war on spores.

Last week, a news broadcast by a Fox affiliate in Manhattan featured PinPointe as the latest thing for nail disorders. Dr. Stuart J. Mogul, a podiatrist in Manhattan who demonstrated the laser during the broadcast, said he had recently treated four patients with PinPointe at a cost of $1,200 each. He said it was too soon to tell whether the treatment had worked.

"I explain to patients that the only risk is financial," Dr. Mogul said in an interview last week.

He added that representatives of PathoLase had told him that the F.D.A. had approved the laser as being safe.

Up until Tuesday, PinPointe’s Web site promoted the toenail laser as "F.D.A. cleared" and included an endorsement from a podiatrist in California saying he had used the device for six months on 225 patients.

Because the F.D.A. cleared the device in 2001 for use in dentistry, doctors are free to use it for other purposes, John Strisower, the chief executive of PathoLase, said in an interview on Monday.

Technically, the F.D.A. does not regulate the practice of medicine, so doctors are indeed able to use approved drugs and devices for unapproved purposes when they deem it appropriate.

But Timothy A. Ulatowski, director of compliance at the Center for Devices and Radiological Health at the F.D.A., said companies were legally allowed to market a medical device only for the specific use for which it had been granted clearance. Selling or promoting a device for unapproved indications is illegal, he said. He added that the company might face action from the agency, ranging from a warning letter to fines, injunctions or product seizures.

In response to a followup call and e-mail message to Mr. Strisower about the regulatory status of PinPointe, a spokeswoman replied in an e-mail message that he was unavailable for comment.

On Tuesday, PinPointe’s Web site went dark before briefly reappearing on Thursday, redesigned for European patients, and then went offline again.

Americans currently spend about $1.26 billion annually on oral and topical prescriptions for nail fungus, according to IMS Health, a health care information company. That is in addition to millions spent on unproved home remedies like tea tree oil, Vicks VapoRub, Listerine and Clorox. Industry analysts and executives estimate that more effective treatments could expand the market to as much as $3 billion annually.

In the meantime, people who have nail fungus — medically known as onychomycosis — can spread it by shedding invisible spores when they walk barefoot in locker rooms or across carpets, and even as they remove shoes and socks.

"The fungi get in under the overhanging edge of the nail and march from the edge of the nail like PacMan all the way to the cuticle," said Dr. Boni E. Elewski, a dermatologist specializing in nail disorders.

Although for the majority of people, nail infection is primarily a cosmetic issue — one of the great unsolved American lifestyle problems, up there with balding and cellulite — it can lead to serious health problems among people with diabetes and immune disorders, said Dr. Elewski, who is also a professor of dermatology at the University of Alabama at Birmingham School of Medicine.