As any properly educated diver knows, the human eye cannot focus decently underwater without the aid of a face mask. In view of this, Dr. Alan Grant and Miss Marcie Farris of Washington, D.C. would appear to be the stupidest divers ever to go below. Actually, they are two of the smartest. In the two months since they took up the sport, neither Dr. Grant nor Marcie Farris has ever worn an orthodox face mask, yet every discrete detail of the trochus shell they are examining in the picture at the left shows clearly, because both of them are wearing what amounts to a tiny face mask on each eyeball. By using specially designed contact lenses as "face masks," Dr. Grant and Marcie Farris are, in fact, able to see better than divers have ever seen before.
Although the lenses that Dr. Grant invented in collaboration with Captain Edward Beckman of the U.S. Naval Medical Research Institute are spectacularly efficient and novel, the physical laws on which they are based are simple and ancient. The effect of any optical system, in the ultimate, depends on how much a ray of light bends, or refracts, when passing at an angle from one medium into another of different density. When light passes from air through the denser components of the eye, it bends considerably, the bent rays gathering into a sharp image on the retina. Since water is only slightly denser than the components of the eye, the light barely bends at all underwater, and the sharp image is formed theoretically far behind the retina. To focus properly on its retina underwater, the eyeball would have to be about the size of a basketball.
Long before diving was a sport or even a reasonably efficient profession, technicians and dabblers had found a number of ways to adapt the eye for use underwater. By far the simplest was to put a boundary of air between the water and the eye so that the full refractive power of the eye remained in force. An orthodox face mask works on this principle—and so do the tiny lenses designed by Dr. Grant. While an orthodox face mask solves the all-important problem of focus, it creates another. A face-masked diver is, in effect, merely looking through a porthole. His field of view is a mere 75°, a drastic reduction from the wide angle of 180° to which he is accustomed above water. But with their contact-type air lenses, which have a front plate barely a third of an inch in diameter, Dr. Grant and Marcie Farris command a view of more than 140°, sacrificing very little of the peripheral vision that makes the human binocular system such a remarkable affair. Any diver who has spent much time hunting fish, avoiding sharks, trying to keep tabs on a diving buddy, taking pictures or doing any kind of underwater work can appreciate the importance of peripheral vision. Anyone else can appreciate it simply by putting on an orthodox face mask on land and trying to go about his usual, above-water business while looking through this narrow tunnel.
The idea for contact air lenses was first born in the mind of Captain Beck-man several years ago while he was involved in a research program that had nothing to do with the underwater world. In determining the effects of acceleration and deceleration on aeronauts and astronauts, it is sometimes expedient to immerse them in water because it is incompressible. It happens that one of the first indications of improper circulation of the blood is loss of peripheral vision. Captain Beckman needed some device that would permit human guinea pigs to use their eyes well in water. His quest took him through Navy channels to Dr. Grant, an optometrist who does normal contact lens work and also specializes in unique contact lenses highly favored by athletes who do not want their expensive optics flying all over the playing field every time they are knocked in the head.
The inner layer of the diver's contact lenses that Beckman and Grant developed are known in the trade as scleral contact lenses because they cover not only the cornea but also the sclera, or white part of the eye. Their particular virtue for any athlete is that they stay put—Dr. Grant, a competent swimmer who trailed in the wake of Ohio State's champions 15 years ago, has done racing dives and leaps from three-meter springboards without losing a lens. Even if a lens should fall out, the diver has little worry: because of the air space between the inner layer and the "face mask" cap, the lenses float. Captain Beckman and members of his research team have worn the contact lenses to a depth of 300 feet with no appreciable loss in acuity.
While peripheral vision is perhaps the major advantage of the lenses, there are others. They are made of unshatterable plastic that is on a par optically with good glass. A diver can focus through them above water as well as below. The air void in each lens is small and is sealed up in a desiccated atmosphere so there can be no fogging. The nearsighted or farsighted diver who needs a prescription built into his face mask can have the same prescription incorporated even more efficiently in his contact air lenses. Without an orthodox face mask blocking his way, an underwater photographer can get his eye properly close to a normal viewing lens. For any diver, equalizing pressure on the eardrums is now simple: with the nose no longer masked, it can be pinched shut underwater as easily as on land. For the proficient free diver who goes 40 feet or deeper on a surface breath, there is no pressure squeeze on the face, or even the impeding resistance of the mask. (One university is considering equipping its swimming team with contact air lenses. If so, its swimmers will have total vision during the critical instant as they approach a flip turn, and they will see every opponent in every lane in the pool.)
Despite their pronounced advantages, the new contact air lenses will never wholly replace the face mask in the market place. Although almost any human eye can be fitted with the lenses, the fitting must be done by an optometrist or an ophthalmologist, and it is doubtful if the cost of a pair will ever go below $100. As is the case with many good products, not everybody who wants them can afford them.
CO-INVENTOR Alan Grant and his assistant, Marcie Farris, try out novel lenses underwater.
HELD FIRMLY in place by eyelids, contact air lens protrudes only about [1/16] of an inch.