In the Naval Academy's class of 2006, 349 of the 993 midshipmen had the surgery, up from 50 five years ago, according to Naval Academy records. Fewer than 30 percent of the academy students whose eyes qualify for the surgery choose not to get it, and the number of holdouts is dropping every year, Pasternak said.

Last week, a little after 10:40 a.m., Colin Carroll, a 21-year-old midshipman from Olney, Md., put anesthetic drops in his eyes and lay down under the laser as Capt. Kerry Hunt, a Navy doctor, and two assistants prepared to begin. "We're locking the laser on now," Hunt told him.

Carroll had originally hoped to enter flight school but discovered not only that his eyes were not good enough, but also that he was prone to kidney stones, ruling him out of aviation entirely. He said he was "resigned" to entering the Marine Corps or becoming an officer on a surface ship, neither an assignment requiring perfect vision.

But he decided to get the surgery anyway.

By 10:49, both eyes were done, though extremely bloodshot, and Carroll walked out wearing sunglasses, declaring he could already see better.

The procedure used by the Navy, photorefractive keratectomy, or PRK, is different from the one used on most civilians. That approach, known as laser-in situ keratomileusis, or Lasik, requires cutting a flap in the surface of the cornea and then using a laser to reshape the cornea. But military doctors worry that the flap could come loose during combat, especially in a supersonic fighter.

So rather than slicing into the cornea covering, Navy doctors grind it away. The approach requires a longer recovery as the covering re-forms but leaves the eye more stable.

The Air Force also limits its pilots to PRK, but nonpilots can get either procedure; because most students admitted to the academy aspire to fly, and have already met strict vision standards, relatively few cadets have the surgery, compared with the number at the Naval Academy. Army personnel, including helicopter pilots and other aviators, are allowed to get either procedure.

One in every 200 midshipmen who has the surgery suffers initial complications, which can usually be corrected, Pasternak said. A study by the Navy soon after the program began concluded that pilot trainees who had the surgery graduated from flight school at higher rates than other pilots, he added.

Now that most midshipmen meet the vision requirements, getting into pilot training is harder than ever, depending almost entirely on academic class rank, military performance while at the academy and other physical criteria.

Last year, 310 midshipmen competed for 272 flight training slots. Of those, 104 had undergone laser eye surgery.