"If we didn't have PRK, where would those 104 midshipmen have gone?" said Capt. Michael Jacobsen, of the Naval Academy's office of professional development. "Tough to say, but we know they wouldn't have gone into flight training."

Expanding the pool of potential pilots and members in the Navy Seals was the original goal of making the surgery available, Pasternak said, but it has become increasingly popular with Marines, who say it eliminates concerns that their glasses will be damaged or clouded in dust storms during combat in Iraq and Afghanistan.

"We get at least five times as many requests every year as we can keep up with," said Pasternak, a 1984 Naval Academy graduate who said he nearly left the academy after learning his eyes were not good enough to allow him into flight training.

The growing number of aspiring pilots has also made it harder to find candidates to become "back-seaters," officers who serve as navigators and weapons officers on planes, Navy officials say.

The failure to produce enough submarine officers, though, is the source of greatest worry to academy officials and the Navy as a whole. This year the academy's quota was 120, but only 88 midshipmen chose to go into submarines, according to academy records.

Acknowledging the decline, Capt. John R. Daugherty, the chief of staff in the Commander Naval Submarine Forces, said in a statement, "There are many potential contributing factors."

The shortfall in the submarine quota is made up from officers joining the Navy who do not attend the academy.

While there are no plans to restrict the availability of the surgery, some Navy officials concede that the procedure contributes to the submarine service losing midshipmen at the top of their class, like Shaughnessy, a native of Rochester, Minn., who formerly could not have gone to flight school.

Going into submarines "requires a lot more school, and after the academy a lot of people aren't looking to go to a high-paced environment for a long period," Shaughnessy said. "And some people also might see submarines as a less glamorous service assignment."

In recent years, many of the midshipmen to choose submarines have come from lower in the class rankings than they did a decade ago, said a senior Navy official who declined to release specific data and who was granted anonymity so he would discuss internal Navy personnel matters.

And academy graduates have been washing out of nuclear power school, which they must complete before being commissioned as a submarine officer, at an increasing rate over the last five years, according to the Navy official and an outside expert who has studied the issue.

In response, the Navy has begun offering $15,000 bonuses and other incentives to get midshipmen with better grades to join the submarine program.