Jewish World Review Jan. 7, 2003 / 4 Shevat, 5763

Focusing on nearsighted children

Experts can predict how bad it will become and are studying ways to halt its progression.

By Kathleen Doheny | Typically, the news comes after the annual school vision screening: Johnny or Jane needs glasses for nearsightedness. More than one of four Americans are nearsighted, according to the American Optometric Association, and some of them so nearsighted that they can't manage daily activities, such as reading the blackboard or a book, or seeing the television, without their glasses or contact lenses.

In recent years, eye specialists have turned their attention not only to insuring that nearsighted children get fitted with vision correction so their learning won't be compromised, but also to two other areas: how to predict the progression of nearsightedness in children and the evaluation of methods to arrest nearsightedness, trying such approaches as bifocal spectacles, rigid contact lenses worn during sleep and a special eye drop.

"The single best predictor of nearsightedness is if you examine kids when they are eight,'' says Karla Zadnik, an optometrist and professor at Ohio State University in Columbus. If children are already nearsighted, they are likely to grow up even more nearsighted, she says. The prediction might be of special interest to parents who are very nearsighted, since they're likely to pass on their vision problems to their children.

When a child is nearsighted, near objects can be seen clearly, but distant objects do not come into focus properly. In the nearsighted eye, the eyeball is too long or the cornea has too much curvature, so that light rays focus in front of the retina rather than on it, producing a blurry image.

Experts debate the exact cause of nearsightedness, but most agree that both nature and nurture contribute. If parents are nearsighted, a child has a higher risk of being nearsighted; frequent close work is also thought to contribute.

When Zadnik and her colleagues looked at children between the ages of 6 and 14 in Orinda, Calif., in a study conducted from 1989 to 2000 and sponsored by the National Institutes of Health, they found that a glasses prescription in the third grade is highly predictive of how nearsighted an individual will become.

"The closer a child is to being myopic at age eight or nine, the more likely he or she is to develop full-blown myopia by age fourteen,'' says Zadnik, who presented a report on children and nearsightedness at the Research to Prevent Blindness meeting in September in Washington, D.C.

In her research, she has also found ethnic differences. In one study, Asians and Hispanics had more nearsightedness than other ethnic groups.

Besides predicting who is likely to become more nearsighted, Zadnik and others are tying to slow down the progression of nearsightedness, turning to spectacles and special eye drops. Some researchers say that fitting nearsighted children with progressive-lens spectacles, in which the lens power gradually changes from the top to the bottom, may help arrest nearsightedness. A wearer of progressive lenses adjusts his head or eye position to use a certain part of the lens, depending on what he is trying to focus on. The interaction of the progressive lenses with the accommodation system of the eye may help reduce the nearsightedness, researchers speculate.

While two published studies show slight improvement in vision in children using progressive lenses, Zadnik says the results are "nothing to write home about.'' But another such study, under way now and sponsored by the National Institutes of Health, may have more promising findings, she says.

Called the COMET study, or "The Correction of Myopia Evaluation Trial,'' it will evaluate 450 children ages 6 to 12 to see if progressive lenses or single-vision lenses work best to arrest their nearsightedness.

Another approach is to fit children with rigid contact lenses that they wear overnight, a vision-correction method known as orthokeratology. It's a noninvasive procedure that involves wearing a series of special, rigid contact lenses (also called gas-permeable lenses) to reshape the curvature of the eye over time.

"They flatten the front of the eye. If they flatten it enough, that could reduce the myopia.'' says Zadnik, whose team is studying that approach.

Her colleague Jeffrey J. Walline, a research scientist at Ohio State, reported in mid-December at the American Academy of Optometry meeting in San Diego, Calif., that children who wore rigid lenses overnight for two weeks could do without their glasses during the day for at least some of the day; and that after wearing them overnight for six months, they could do without their glasses all the next day. The study was small, including just 27 children. The researchers next want to see if the overnight lens wear will slow the progression of nearsightedness.

Special eye drops may arrest the progression of nearsightedness, say researchers from Valley Forge Pharmaceuticals, a firm based in Irvine, Calif. The drop, now under study in clinical trials, is pirenzepine. "In animal models, it appears to control the growth of the eye,'' says Jim Socks, an optometrist and vice president of clinical operations at the company. "It doesn't bring them back to normal,'' he adds. Rather, the drops look as if they keep the condition from progressing.

The clinical trials include 14 U.S. sites and seven in Asia, Socks says. The eye drops are in gel form, dropped into the eye twice a day in trials. "We are in the early stages of development and have a long way to go,'' he says. If the trials progress well, the eye medication could be available in four years or so, he adds.

If any of the treatments being studied to slow down the progression of nearsightedness work, says Zadnik, it would be logical to extend them to try to prevent the onset of nearsightedness in those children at high risk.

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© 2003, TMS