MARINE CORPS AIR STATION MIRAMAR, Calif. -- Eyesight regulations for pilots, Naval flight officers and aircrew have recently changed, due to extensive studies involving flight and the effects of wearing eyeglasses.

The changes may open the window of opportunity for many who thought they were ineligible to be Marine Corps or Naval aviators.

According to Navy Capt. Mark Edwards, 3d Marine Aircraft Wing surgeon, the changes have already been approved at Headquarters Marine Corps, and it's only a short matter of time before the changes are written in an official message.

"The vision standards have loosened up a bit, in other words, they're not as stringent," said Edwards.  "The reason is because we've found medically they don't have to be as strict as we thought they needed to be. We've had enough years of experience (with aviation), so we've expanded the pool of candidates committed to aviation.

Originally, candidates had to have 20/20 vision to be accepted into the pilot program. Edwards said those requirements had loosened to 20/30. With the new changes, Naval Aviator candidates can now have 20/40 eyesight. Edwards said pilots who see 20/20 naturally and pilots who wear glasses to correct their eyesight to 20/20 have the same flying ability.

"We didn't find any problems in terms of a division," he said. "The fact that one wears glasses -- he still functions well. With glasses they do just as well as somebody who sees 20/20 (naturally).

Another change was the removal of depth perception requirements for aircrew members. Edwards said the part of depth perception which can be tested is actually rarely used in a real-world situation.

"They eliminated depth perception, and that's a tricky one because the only thing we are able to test is binocular vision -- using your two eyes to get a three-dimensional field," he said. "(Using) both eyes for depth perception only works for a certain distance. Beyond that, the fact that you're looking with two eyes doesn't help you tell distance."

He said it's what humans actually see from their visual cues -- something is in front of or behind something else -- that doesn't work with binocular vision. Until now, the Navy and Marine Corps has only tested the part of depth perception that is helped by having binocular   vision. According to Edwards, after a certain distance, binocular vision doesn't help a person.

"You're forming a triangle, and your brain interprets that and gives you an idea that -- hey, this is three dimensional and that's how it looks,'" he said. "But if you look far enough, this triangle is so small, it doesn't make any difference."

While Edwards stresses the importance of depth perception, he concedes that the part tested is only a small part of depth perception and may not be as critical.

"What happens in real life is that people learn depth perception, and just from experience and looking from a distance (they) learn that something is closer or farther away," he explained. "It has nothing to do with the physical characteristics you have."

Another change to aviation's vision standards is allowing for a waiver for Photorefractive Karatotomy. Although not yet allowed, Edwards said that a large study is currently being conducted by the military about the effects of flight on eyes that have had PRK.

"That is actually the wave of the future," he said. "A lot of people, instead of wearing glasses, are getting surgery to improve their vision. It's still considered not physically qualifying -- we don't want people who've had it done coming into the program because we don't know the long-term effects."

He said currently thousands of aircrew members are getting the procedure done as part of the study, and they are being monitored to see how it affects them.

"So far the results are very promising -- they seem to be doing fine," he said. "We are looking at short-term effects, long-term effects, and if it becomes ok, then we may allow people to come in with certain types of procedures. We just don't know enough about it yet."

One of the main reasons for the change in policy is because of a lack of eligible people in the officer candidate pool. Edwards said it is not medically necessary for pilots to have 20/20 vision, like in the infancy of the aviation program.

"Now we've found out that medically, you don't have to be as strict with glasses," he said. "As we get more comfortable and learn more, we'll probably push it a little more or maybe we'll accept people who have had eye surgery into the pilot program. I think eventually we'd like to do that because I know there are many very motivated people who couldn't get in because of their vision."

Maj. Patrick O'Donnell, Marine Fighter Attack Training Squadron 101 assistant aircrew training officer, said he doesn't think the new changes will affect the quality of the aviation program.

"It doesn't change much of anything," he said. "(Wearing glasses) doesn't have any effect on performance if (the pilot) sees what is required and he knows how to find it. It may open up more opportunities for individuals."

Captain James Keller, officer selection officer, Recruiting Station San Diego, is one of many who are very excited about the change.

"This will open up the door of opportunity for people who now meet the criteria," he said. "It's going to expand people's possibilities in the Marine Corps by not limiting them to certain MOSs because of eyesight."