My optometrist was puzzled. Even though I was approaching 30, my eyes still were becoming progressively more nearsighted.

"This isn't supposed to happen in an adult," Dr. Arthur Dorman of Langley Park told me. "If you were a kid, I'd fit you for bifocals or reading glasses."

Bifocals for kids? Reading glasses for extreme nearsightedness? As I asked more and more questions, Dorman expounded on a set of theories that made it sound like my formative years had been spent in the optometric Dark Ages. Maybe, I began to hope, my children could be spared the short-sighted fates of their parents -- fates I had, until then, assumed were genetically sealed.

In brief, the emerging theory about nearsightedness, or myopia, is this:

Close work makes the eyes work too hard; close work plus distance glasses makes them work even harder. When the eyes work too hard, one of two things happens -- either they elongate as a result of increased pressure inside the eye, or the muscles controlling the lens become "set" in a position that bends light rays too sharply to focus distant objects properly. In either case, the eyes become more nearsighted.

The only way to stop this cycle, short of giving up reading and other close work altogether, is to make "nearwork" activities -- reading, sewing, drawing, using a computer -- less stressful on the eyes. And that's where bifocals come in. By allowing the eye to focus on nearby objects without an increase in eye pressure or a tightening of the lens muscles, bifocals take the strain out of close work.

Hypotheses about myopia have been around for years. In 1813, a British eye doctor found that soldiers, who tended to be illiterate, rarely were myopic, while officers, who were well-educated, often were. Thus, he postulated that reading led to myopia.

In 1883, a scientist ranked 7,500 Dutch military recruits according to former occupation, and found -- like the British doctor -- that nearsightedness became more prevalent as the educational attainment rose: from 2.5 percent among farmers and fishermen, to 12 percent among craftsmen doing close handiwork, to 32 percent among scholars.

In 1920, Dr. William Bates, a New York ophthalmologist, published "The Cure of Imperfect Sight by Treatment Without Glasses." Distinguished followers such as Aldous Huxley turned the Bates method of eye exercises into a household word.

But the modern version of this hypothesis -- the "nearwork theory of myopia" -- is still controversial. The American Optometric Association says that few practitioners -- who call themselves "developmental optometrists" -- currently are treating nearsightedness with eye exercises or bifocals, and even fewer are trying to prevent nearsightedness by fitting non-myopic children with special "plus" lenses for reading. (A plus lens, usually prescribed for farsightedness, is fatter in the middle than on the edges and makes objects seem larger. A minus lens, prescribed for nearsightedness, is thinner in the middle and makes objects seem smaller.)

Of the nation's 22,500 practicing optometrists, says the AOA, about 9,000 are performing some vision training (typically eye exercises in which the patient is forced to shift focusing distance to strengthen the eye's ability to shift focus) for myopia and other conditions; of those, about 5,600 are involved in developmental vision therapy, which includes preventive steps.

Mainstream optometrists remain skeptical of these new anti-myopia techniques, and many ophthalmologists (medical doctors who treat eye diseases) are highly critical of them.

"There's absolutely no evidence that wearing reading glasses does anything to prevent nearsightedness," says Dr. Marshall Keys, a pediatric ophthalmologist in Rockville. "There's a great deal of expense associated with this treatment, a certain amount of time commitment, and a certain amount of guilt that the parents assume -- especially in a family where the parents are wearing glasses and already feel bad about passing on myopia to their children. But I've never seen a case where it works, or where it reduces the severity of the nearsightedness.

"Considering how much the examinations, the exercises, the frequent changes of eyeglasses are all costing, I would question the motives of these practitioners."

Costs can include $60 for a one-hour exam, at least $100 for special bifocals, and repeated visits for exercise training with a vision therapist at $25 each.

With nearsightedness affecting ever-growing numbers of us, at increasingly younger ages and with increasing severity, any effort to prevent it holds obvious appeal. In 1930, an estimated 14 percent of Americans were nearsighted. Today, more than twice that proportion -- about one third of us -- are. The incidence of myopia is increasing at an estimated rate of 1 percent every three years. At that rate, by the 22nd century we might all need glasses.

Vision is worsening, according to proponents of the environmental theory, because we live in an information-oriented society, where close work is an integral part of most people's lives. Geneticists say we're increasing the gene pool for myopia because -- unlike in earlier times -- nearsightedness is not a disability that keeps people from thriving and reproducing.

Certain occupational and ethnic groups seem at especially high risk for myopia. Nearsightedness is common among professionals; the more years spent in school, the greater the chance of an individual being myopic. Lawyers and graduate students have myopia rates approaching 50 percent.

In addition, certain ethnic groups, particularly Jews and Japanese, are more likely to be nearsighted. The reason for these ethnic tendencies is unclear. Environmentalists would ascribe myopia among Jews to their scholarly habits, among the Japanese to the intricate work required to read and write their alphabet. Geneticists would blame it simply on myopic gene pools.

Nearsightedness usually is a relatively benign problem. The great majority of myopic individuals can be corrected to near-perfect vision with glasses or contact lenses.

But it isn't always harmless. Myopia is the leading cause of blindness among Americans in their fifties, the second leading cause (after diabetes) for those in their sixties, and the fourth leading cause of blindness for all ages, notes Dr. Edward Perkins, professor of ophthalmology at the University of Iowa. Extreme myopes run a higher-than-normal risk of retinal detachment, atrophy of the retina and choroid (the skin-like encasement of the eyeball), glaucoma and cataracts.

For an object to be seen in focus, its image must fall precisely on the right spot of the retina, the screen-like membrane at the back of the eyeball. In the normal eye, the focusing power and the length of the eyeball are in perfect balance. The eye's optics (the cornea and lens working together to bend light rays) are ideally suited to the distance between the lens and the retina. So when all is working normally, the cornea and lens bend light rays just enough to have them converge precisely on the retina.

In the farsighted eye, the eyeball is too short for its optics, or the optics are too weak for the eyeball. As a result, the light rays don't converge until a spot somewhere behind the retina.

In the nearsighted eye, the opposite is true: the eyeball is too long for its optics or the optics are too strong for the eyeball, and the rays converge somewhere in front of the retina.

Most of us are farsighted in early childhood. And it's a good thing, since kids spend so much time looking into the distance. But when we learn to read, we need to see the world up close, too. To do this we use a visual process called accommodation. To focus on something less than a foot or two away, the ciliary muscles that control our lenses must contract. This bulging, or accommodation, in turn makes the lens bulge, bringing the nearby object into focus on the retina.

According to the nearwork theory of myopia, we actually change the configuration of the eye by excessive use of accommodation. The more we require the ciliary muscles to contract and the more we require the lens to bulge, the theory goes, the harder it becomes for these structures to return to their normal, relaxed state. In addition, during accommodation the pressure within the eyeball increases. If accommodation occurs too often and the intraocular pressure stays high for too long, the eyeball might respond by elongating.

"If you understand accommodation, you understand myopia," says psychologist Francis Young, one of the leading proponents of the nearwork theory. Young is director of the primate center at Washington State University, where he has raised one of the world's largest colonies of nearsighted monkeys by restricting their visual environments to between 14 and 20 inches, forcing them to accommodate full-time. After just one year, Young's monkeys developed myopia (determined by measurements of the eye's length and light-bending powers) at an alarming rate -- about five times the rate of other monkeys.

In the world, where distance vision is necessary for survival, there's no such thing as a nearsighted monkey.

Young observed a similar pattern among the Eskimos of Barrow, Alaska. The first generation of Eskimos he studied -- illiterate nomads who spent six months of the year in near or total darkness -- were extremely farsighted. Their children, who benefited from the introduction of better housing, voluntary education and electricity, were mildly farsighted. And their grandchildren, for whom schooling was compulsory and television and reading a way of life, were as nearsighted as their peers in the lower 48.

Concludes Young: "It is difficult to conceive of a genetic change of this magnitude in two generations."

"You could look upon myopia as a sensory adjustment to a behavioral situation," Young says. The eye is an inherently farsighted organ; when we ask it to behave in a nearsighted way, it changes its shape to perform more efficiently. "In an individual who is regularly doing a great deal of nearwork -- reading, sewing, playing Pac-Man -- the body reacts with changes that make it easier to maintain accommodation."

Young contends that mainstream eye doctors criticize his views because they fear the wrath of their patients. It could generate some "horrendous" malpractice suits, he says, for people suddenly to "discover they didn't have to be myopic, they didn't have to have retinal detachment, they didn't have to have glaucoma -- if only someone had done something about it when they were young."

"That's the way things are perceived, with the medical community sitting around and deciding to withhold therapies," says Dr. George Garcia, an optometrist-turned-ophthalmologist from the Harvard Medical School. "But if we really had good evidence that some form of vision therapy or some particular nutrient could provide protection against myopia, I can't imagine anyone withholding it."

What can be done to prevent myopia? In a way, this seems as futile as trying to prevent long-leggedness, or blondness, in a child whose parents are long-legged blonds.

My husband and I are both so nearsighted that we dare not buy a king-size bed for fear of losing each other. My mother used to joke that our children would come into the world squinting -- and, indeed, our younger daughter was found to be slightly myopic when she was just 9 months old. Is there any hope that our two girls will be anything but extremely nearsighted?

Yes, says Dr. Morton Davis, a developmental optometrist in Bethesda. Davis and his partner, Dr. Harold Glazier, have one of the largest practices in the country devoted to vision therapy. With their methods, they claim, the rate of increase of myopia can almost always be stopped if caught early enough -- and sometimes even reversed. And in a few fortunate cases, nearsightedness actually can be prevented.

Davis and Glazier, and their counterparts across the country, offer two ways to prevent myopia: either stop the stressful action (the nearwork) or make the stressful action less stressful. The first choice is all but impossible in a literate society; the second involves bifocals.

With bifocals, a myopic child does his close work through a plus lens fitted into the bottom half of the spectacle. (If he doesn't need glasses at all, he can wear the plus lens alone just for reading.) The plus lens behaves like the reading glasses that people over 40 often wear: it allows the wearer to see up close without accommodation.

But while older adults depend on reading glasses because they have lost the ability to accommodate, Davis and Glazier's patients use the glasses for a different reason. They use them so they won't need to accommodate.

With the plus lens, reading is an optically stress-free experience. The patient can focus on the book even though his eyes are relaxed. When the stressfulness of close work is removed, the theory goes, the eye's response to stress -- accommodation and elongation -- will be avoided.

Such efforts have had some effect in the past. Dr. John Streff of the Optometric Extension Program Foundation fitted plus lenses for children in one Connecticut grade school, and showed that they became less myopic than did their peers at other schools. Streff is now using plus lenses on children at a school in Ohio.

Francis Young is conducting a controlled clinical trial in Houston to test the value of bifocals in the improvement of myopia. He is working with a developmental optometrist, Dr. Theodore Grosvenor of the University of Houston College of Optometry. The scientists have divided nearsighted children into three groups -- a control group who wear regular glasses, an experimental group who wear glasses with a plus prescription in the bottom half for reading, and another experimental group whose plus prescription is even stronger.

Preliminary results are that the bifocals did not retard the progression of myopia, Grosvenor says. "Although it is still theoretically sound to prescribe bifocals for children with myopia," he says, "our results do not show any statistically significant difference when you do so."

Grosvenor says that his 200-plus subjects, most of whom were aged 10 to 15, might have been too old for the plus lenses to do any good. "If bifocals can help at all," he says, "it would proably be when a child first starts to become myopic. Once the eye begins to stretch, then it's hard to stop it."

But few children will submit to wearing glasses of any kind before they really need them to see. Three children who did -- and who seemed to benefit from it -- were the children of Morton Davis, the Bethesda optometrist. With two nearsighted parents, says their father, the Davis children probably had the genetic endowment for myopia -- given the right environmental stress. And since all three were avid readers, their environments were prime for myopia, too. Davis fit his son and daughters with plus lenses for reading from the time they were 5 or 6 years old. And today, more than 20 years later, they all still use plus lenses for close work. All have completed graduate school -- placing them in the group of Americans at highest risk for myopia -- and though Davis' son is slightly myopic, his two daughters (one of whom is an optometrist in practice with her father) have perfect distance vision.

Other investigators, such as Dr. Robert Bedrossian of the Southwest Washington Hospital in Vancouver, have tried inhibiting accommodation by the use of atropine, an eyedrop that relaxes the ciliary muscle and makes the eye unable to accommodate. A typical pattern is for a child to use atropine in the right eye the first week, in the left eye the second week, in the right eye the third week, and so on. The eye with the drop is useless for reading and other nearwork, but the unmedicated eye easily takes over. According to investigators involved in this work, the atropine successfully retards progression of nearsightedness in the treated eye -- but the progression returns as soon as the atropine treatments stop.

Not everyone agrees with the nearwork theory of myopia. Yes, literate cultures have more myopia than illiterate ones. Yes, heavy readers -- college and graduate students, professionals, persons with high IQs -- have up to twice the rate of nearsightedness as the general population.

But which came first, the myopia or the avid reading?

"The correlation between myopia and nearwork has been used to support the nearwork theory," says Dr. David Goss, professor of optometry at the Oklahoma State University. "You could as easily argue that an already-myopic person is drawn more to nearwork because he can see it more efficiently."

This chicken-and-egg argument is not merely academic. According to Dr. Aran Safir, former professor of ophthalmology at the University of Connecticut School of Medicine, proponents of the nearwork theory do a great disservice to nearsighted Americans. Safir says they inevitably make myopic individuals feel responsible for -- and guilty about -- a hereditary condition over which they have no control.

"I'm willing to believe that there is some environmental contribution to myopia," he says. "But I've seen not one acceptable article in the medical literature that demonstrates with reasonable certainty that environment plays any role. Based on that lack of information, I cannot see a reason to invade and influence someone's life style, to make an individual feel that in some way he's done something wrong.

"That's a terrible thing to do to a 12-year-old, when it's bad enough to have to wear glasses. This is the time when he's just getting involved in athletics, trying to be attractive to the opposite sex, and trying to develop a positive self-image. He comes to view his glasses as a scarlet letter, as proof of his own weakness."

Safir criticizes the research methods of the environmentalists, especially the absence of repeated eye measurements before treatment and the lack of control for investigator bias. And he questions the logic of their basic assumptions about cause and effect.

" 'Oh, you have myopia!' they say. 'It must have been from when you were in fifth grade and doing all that schoolwork.' I tell people that that's about the same age at which girls develop breasts, and no one is ascribing the development of breasts to schoolwork.

"People laugh when I say that," says Safir, "but I want to show them that the same ridiculous reasoning has been applied to myopia."

Safir concludes that myopia is hereditary. "Why should it be surprising if the shape of your eye is related to the shape of your parent's eye?" he asks. "No one is surprised if your face looks like your parent's face, or if your body is shaped like your parent's. It would be surprising if it were any other way."

Even those who believe there might be an environmental cause of nearsightedness are uncertain what the cause might be. The nearwork theory is the most prevalent, but there are others: that myopia is caused by excessive sugar or protein in the diet, by deficiencies of calcium, or by deficiencies of chromium or other trace metals.

Ophthalmologists tell parents to watch for myopic symptoms in their children -- squinting, tilting the head, inability to see distant details -- and then to correct the nearsightedness with plain minus glasses.

"All children need a complete eye examination before they begin school," says Keys of Rockville, "and by complete I mean an exam in which the pupils are dilated and objective measurements of refraction are made. Many children are tested for sight with an eye chart, but you cannot rely on subjective responses in children. A complex series of processes goes into reading an eye chart, and vision is only one of them."

Which leaves me and my fellow myopes right back where we started from. The ophthalmologists tell us to relax, because neither we nor our eye doctors can do anything about our vision other than to get the best corrective lenses. But the developmental optometrists tell us to get working, because we have the power to halt the progression of our own nearsightedness, and to prevent it in our children.

For what it's worth, here are the tentative decisions I have reached for my own family: My 5-year-old, Jessica, is now a patient of Dr. Davis. I have mixed feelings about whether her bifocals -- which give her such a cute, studious air -- are really going to make a difference. This antimyopia routine has its drawbacks, chief of which is that it turns me into a nag.

I hate searching for Jessica's glasses before every meal and reminding her to use them whenever she reads, eats or draws. Still, it would seem a small price to pay if the glasses keep her from developing 20/600 vision like mine. But I'm only giving them another year or two to start working, and then I'll begin wondering if I really need to create another issue to fight about with my daughter.

And just to demonstrate my ambivalence: My 1-year-old, Samantha, is now a patient of Dr. Keys. Samantha already has myopia in one eye, and also has a condition that makes that eye sluggish in its movements and prone to "lazy eye." Frankly, with problems like that, I don't want to take a chance that the environmentalists may represent a passing fad.

As for my own vision -- well, I think I'll just go back to those studies about the intellectual superiority of myopes, and take solace in them as I once again push my heavy glasses back up the bridge of my nose.