Staring through a microscope, Dr. A. Edward Maumenee made a slit through an eye muscle.

He took a few stitches to hold the open, staring eye still.

He quickly cut through the sclera, the eye's tough, white coat, and turned aside the cornea, the eye's window.

Then he gently peeled back the wheel-shaped, tinted iris to get at the lens.

The lens was clouded and dull. Gray. Murky. Useless. In a day of a new vision revolution, this noted Johns Hopkins eye surgeon was about to insert a new artificial lens, a piece of plastic that might confer 20-20 vision or something near it to his patient's unseeing eye.

In the best operating rooms, in opthalmologists' and optometrists' examining rooms, many of the half-blinded are being returned to 20-20 or at least useful vision. New knowledge, improved contacts and new operations -- like the one at Johns Hopkins Hospital -- are making this possible.

The surgery can be two-edged, however, at the hands of less skilled eye surgeons, and occasionally at the hands of the best, it can sometimes reduce rather than enhance sight and even leave an eye blind.

So there is a question: are some or most people better off with the 500-year-old answer -- eye glasses -- than with the implanted lenses? The answer is yes. "I myself wouldn't have surgery if I could get by with contacts," said Maumenee of the operation he was doing: one to implant a plastic lens after a cataract operation, which destroys the old lens.

A debate is taking place within medicine and government over the new implant surgery, and whether, however wonderful it is for some people, it has become common too fast.

In the words of Dr. Norman Jaffe in the New England Journal of Medicine, a "whirl of technological advances has had an intoxicating effect on American ophthalmology," and "the most exciting development of all" is the intra-ocular or inside-the -eye plastic lens.

The eye, Mamenee explained, is a nearly perfect sphere. If by aging or damage or nature's perversity, the sphere becomes irregular, or its light-focusing lens loses its elasticity, or the eye's muscles weaken, or some area becomes damaged, then "correction" is needed.

The damage in his patient's eye was the devatstating destruction of vision caused by a cataract.

Literally a "waterfall," a cataract is a cloudy or watery dimming of the normally crystal-clear lens, the part of the eye that channels incoming light rays onto the nerves of seeing deep inside the eye's sphere.

In the Johns Hopkins operating room, the cloudy, useless old lens was now exposed. Maumenee inserted a cryoprobe that quickly froze this otherwise elusive, rubbery body. He lifted it out and laid it aside.

He blew in an air bubble to push back temporarily the vitreous jelly that fills the eyeball. Then he slid in the round artificial lens, a wafer of paper-thin plastic a fifth of an inch across.

He sewed the new lens' tiny side-clips to the iris. Some finishing touches and sutures and the operation was over. Harcdly 43 minutes had passed since its start.

In 1967, 167,000 cataract operations were done in the United States. By 1978 the total was 400,000.

Why the sudden increase?

In part, it is because of our aging population, though not all cataracts occur in the aging. The new surgical methods make it easier to remove cataracts. And since 1966, there has been a flood of federal Medicare money to finance these operations -- too much money, tempting many surgeons.

At the same time, both the new, implanted lenses and new contact lenses have appeared to supplant the old cataract lenses, the bottle-glasses that overmagnify by 30 percent and otherwise distort vision. About half of all cataract patients still manage with cataract lenses. A quarter use today's improved contacts. The other quarter have the lens-implant operation.

By varying reports, the surgery succeeds in 85 to 97 percent of cases, depending on care in choosing suitable patients, the surgeon's ability and, sometimes, his candor.

Jaffe, first American to push the intraocular lenses, maintains that with proper patient selection and technique, the complication rate is only "slightly" higher than in ordinary cataract surgery. Some federal figures seem to back him up.

But Maumenee, who at 66 is one of the world's most experienced eye surgeons, says "what bothers me" is that after three or five more years, the implanted lenses may cause inflammation and swelling and, at times, loss of vision.

He says some 7 percent of lens-implant patients have these problems, compared with 1/2 of 1 percent of ordinary cataract patients. He says that only 87 percent of implant patients achieve 20-40 vision or better, compared with 95 percent of cataract conact-lens users.

A California Blue Shield study indicated that 12 to 15 percent of northern California Medicare patients who had lens implants in 1976 and 1977 needed repeat operations for complications. Half had the offensive lens removed.

The California study needs verification. But Dr. Thomas Chalkley of Chicago says that in the last 20 months he has been asked to reoperate to correct complications in 23 patients who had the plastic lenses inserted by other surgeons.

Two of these patients had the lenses inserted in both eyes, and ended up legally blind in both. Seventeen others, most of whom had the lens placed in only one eye, wound up with some handicap, ranging from poor vision to near-blindness.

Robert Leflar and Dr. Sidney Wolfe of the Public Citizen Health Research Group -- and Jaffee -- think too many lenses are being implanted by ill-prepared surgeons. Some of the lenses themselves have proved faulty. Some authorities think too many cataract operations are being done altogether. s

Still, some persons, especially the old and disabled, cannot possibly cope with or even insert contacts. Some persons who can't or won't wear contacts must have good vision to work.

Considering many factors, doctors attending a "consensus conference" at the National Institutes of Health agree that the implants should be limited to older patients -- Jaffe says over the age of 55 -- and be used in only one eye in most cases.

The surgery is still "investigational" -- a milder word for experimental -- by Food and Drug Administration definition. Anyone considering an implant, says Wolfe, should find out or be told how much risk he or she faces, which lens makers and lens styles have the best safety records and whether the surgeon has had adequate training -- preferably at a good teaching hospital -- and good results.

Given proper caution, said Maumenee, results can be impressive. "We treated a noted author," he said. "He'd had just a terrible time wearing contacts. He had an implant and left with 20-20 vision."

Who wears contact lenses? In large part, teen-aged girls and young women, after which they often go back to eye-glasses. The American Optometric Association says among all contact-wearers, 73 percent are female; 46 percent are aged 17 to 24; 36 percent, 25-44, and only 10 percent, 45 or older.

But older wearers are increasing, as newer contacts feel less like "something in the eye." It was only in 1936 that a New York opeometrist, Dr. William Feinbloom, made the first plastic contact lens, a hard transparent disc set atop the cornea and held in place by surface tension of the eye's natural fluids. A contact lens rides on tears.

A decade ago there were still only 4.5 million Americans wearing contacts. Today the number has tripled, and there are hard lenses, soft lenses (made of liquid-absorbing plastic) and ultra-thin hard-soft lenses, oxygen-permeable so the eye can "breathe" and only a quarter as thick as standard hard lenses.

There are also new extended-wear softlenses, so thin and comfortable, many persons find, they can be worn night and day, even while sleeping, for a month. They have been worn as long as six months, in fact, in some study groups. Their comfort secret: they are made of a material that is up to 80 percent water.

The FDA last June approved two brands of these "membrane lenses" for up to 30 days wear in only one group so far: cataract patients, for whom they may be much safer than plastic implants. "Results to date have been very promising," says the Harvard Health Letter. It found these lenses successful in eight patients in 10, with good vision and few serious complications.

This does not mean eight in 10 will necessarily be wearing them indefinitely. One doctor at the NIH "consensus" meeting felt that figure might be four out of 10.

Any foreign body left in the eye indefinitely may cause complications. Similar lenses have caused some severe vision problems in Europe, where they have been on general sale. The FDA hopes to avoid these problems by more testing and more careful marketing -- more careful, perhaps, than the marketing of the plastic implants. Some models of these have had to be recalled because of eye damage.

Harvard Dr. George Garcia is nonetheless optimistic about future contact lens developments. "New materials offer exciting prospects," he said. "We can foresee inexpensive lenses that can be worn for a month or so and then thrown away."

What is ahead in the operating rooms?

A handful of eye surgeons -- in New York, New Orleans, San Francisco, Bogota, Colombia, and Moscow -- are remaking patients' eyes.

Some make what are, in effect, living contact lenses. They carve natural lenses from frozen cadaver corneas, then suture them between the fine layers of their patients' corneas to change the eye's shape. The aim is to correct extreme far sightedness.

Or, in a similar procedure, they carve out a thin slice of the patient's cornea, freeze it, then reshape it on a miniature lathe, according to a computer's directions, while their patient is still on the operating table. Then they replace the remade part, having, they hoped, improved the eye's focusing to correct near-sightedness.

Such reshapings were pioneered, and are most done today, by Dr. Jose Barraquer, a brilliant Colombian eye surgeon who started the surgery nearly 20 years ago and has operated on more than 1,500 eyes.

A flamboyant Moscow eye surgeon, Prof. Svyatoslav Fyodorov, makes 16 shallow incisions all around the rim of the cornea -- in the "non-seeing" part, he says -- to weaken the cornea just enough to let internal eye pressure flatten its curvature. In this way, he says, he has corrected near-sightedness and "made glasses unnecessary" for 1,300 persons.

All these techniques are regarded as highly experimental and uncertain by Nih's National Eye Institute. NEI says: "People who require only eyeglasses or contact lenses to correct their vision must carefully balance the minor inconvenience of wearing corrective lenses against the risks of any operative procedure . . . . These risks include the possibility of . . . visual impairment . . . . At present, the only proven treatment for refractive errors is correction with eyeglasses or contact lenses.

Yet these operations, or related forms, are gradually spreading. They could spread faster than contact lenses or insertion of plastic lenses because "devices" can be controlled by FDA but new operations cannot.

Dr. Richard Troutman, a prominent New York eye doctor, calls Fyodorov's operation "like playing a little Russian roulette with your cornea -- six shots and hope it comes out all right." Dr. Carl Kupfer, NEI director, says Fyodorov's corrects only "trivial," not serious, near - sightedness, and uses too dangerous an instrument -- the knife -- to correct a condition that can be fixed by safe glasses.

Fyodorov, however, maintains, "Man has been held in bondage to spectacles for the last 500 years. . . . We believe that soon spectacles will take their place with horses and buggies, and we will visit them in museums."

And Troutman, who does a variation of Barraquer's far-sightedness operation, says that while Fyodorov's method is "not necessarily" the right one, the cornea "does offer the optical possibilities -- it only remains to correct the technique." He says, "I think eventually we will be able to do this [Barraquer] procedure so exactly that no one will require glasses."

"These fellows eventually may be right," said Dr. Malcolm McCannel, a prominent Minneapolis surgeon and plastic lens implant backer. " but right now they won't operate on me."

For the future, laser surgery, corneal transplants with cross-match tissue testing, opthalmologic genetics and vitreous surgery are seen by a Johns Hopkins annual report as "some of [this] appears to be out of the 21st century."

Eyeglasses, too, may advance. David Ouellete, 31, of Santa Monica is wearing a pair of experimental $2,000 telescope-like "camera lens spectacles" made by optometrist William Feinbloom.

Ouellette, who has had only 3 percent vision since childhood -- most of the legally "blind" have some vision -- has 85 percent vision with these glasses.

Yes, they are strange looking. Some people find them too hard to manage. But "how many people get to be reborn. It's like coming out of the womb," Ouellette says.

"The gift of sight," says Feinbloom, "is a miracle not to be missed."