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Myopia Control

By Gary Heiting, OD

When parents learn that their children have myopia (nearsightedness), questions they frequently ask include:

• "What causes nearsightedness in children?"
• "Is there a myopia cure?"
• "Is there something that can be done to control myopia so his/her eyes don't get worse?"

Myopia in children is a growing concern because of the increasing prevalence of nearsightedness in recent decades. In the United States, myopia affected about 25 percent of the population in the 1970s. Today, more than 40 percent of Americans are nearsighted.

In other parts of the world, the picture is even more grim: In Asia, for example, a recent study found the prevalence of nearsightedness among Taiwanese children ages 16 to 18 was 84 percent. Other studies have found that up to 90 percent of teenagers graduating from secondary school in east Asian cities are nearsighted.

Whether the worldwide increase in childhood myopia is due to computer use, increased reading demands, dietary changes or other factors, these startling statistics raise the question: Can anything be done to slow or stop the progression of myopia in children?

Or are some children simply destined to be nearsighted — and to have their myopia increase year after year?

Why Is Myopia a Concern?

In addition to the cost of new eyeglasses and contact lenses every year, many children who get more nearsighted year after year end up with high myopia as an adult. ("High myopia" generally is used to describe myopia greater than -6.00 diopters. A person with high myopia cannot see even the big "E" on an eye chart without corrective lenses.)

I speak from experience here: I got my first pair of glasses for myopia when I was 8 years old, and I became more nearsighted nearly every year until I was 20.

Because my glasses became so thick, I started wearing contact lenses when I was a teenager, and I still wear them today. But now I also wear reading glasses, computer glasses, and multifocal glasses with progressive lenses — depending on what I'm doing that day, and my mood! (Ugh...things get complicated with age!)

And there are risks associated with high myopia. Many people like me who are significantly nearsightedness are at greater risk for cataracts, a detached retina or other serious eye problems. And some of us are too nearsighted to be good candidates for LASIK and other laser vision correction surgery.

What Causes Myopia in Children?

Though the exact reason why some children become nearsighted and others do not is not fully understood, it appears heredity is a factor, but not the only one.

Are bookworms more likely to be nearsighted than other children? Some researchers and eye doctors think so, but the evidence is not clear-cut.

In other words, if both parents are nearsighted, there is a greater risk their children will be nearsighted, too.

But you can't predict who will become nearsighted by simply looking at their family tree. In my case, neither of my parents were nearsighted; and I have two brothers — both have perfect vision. I'm the only one in the family who is myopic. Go figure.

I loved to read when I was a kid (still do); my brothers, not so much. Some researchers think focusing fatigue from excessive reading or holding a book too close to your eyes for extended periods can increase the risk for myopia in children. But nobody knows for sure.

The cause (or causes) of myopia may remain a mystery, but researchers recently have discovered something about the progression of nearsightedness that is very interesting: conventional glasses and contact lenses that your family optometrist or ophthalmologist prescribes to correct myopia may actually increase the risk of myopia worsening throughout childhood!

Many of these same researchers are investigating new lens designs to see if they can develop contact lenses or eyeglasses that can halt or slow the progression of nearsightedness in children.

Peripheral Blur and Myopia Progression

Over the years, eye doctors have attempted several methods to control nearsightedness in children — with limited or little success (see below).

But recently, researchers have gained a greater understanding about how the eye responds to traditional corrective lenses, and this new information may significantly improve efforts to slow or stop the progression of myopia.

It turns out that although conventional eyeglasses and contact lenses do an excellent job of correcting existing myopia and restoring clear central vision, they may cause unwanted effects on peripheral vision that could increase the risk of myopia progression.

Researchers in Australia, the United States and elsewhere have found that a specific type of blur (or "defocus") that can occur in the peripheral retina may help stimulate the eyeball to lengthen during childhood, which causes increasing nearsightedness.

Here's where it gets interesting (and a bit complicated, so stay with me): A nearsighted eye often is less myopic in the peripheral retina than it is in the central retina. When traditional eyeglasses or contact lenses accurately correct myopia and restore eyesight to 20/20 in the central retina — the part of the eye that controls our most precise vision for tasks such as seeing the board in a classroom, or reading an eye chart — they may actually cause greater defocus in the peripheral retina.

The myopia in the peripheral retina essentially is over-corrected, which causes a type of blur called "hyperopic defocus." Researchers believe it is this hyperopic defocus in the peripheral retina that may stimulate lengthening of the eye and progressively increasing myopia in children.

These same researchers believe that if you can develop contact lenses or eyeglasses that eliminate hyperopic defocus in the peripheral retina — or perhaps even change it to myopic defocus (making the peripheral retina slightly nearsighted, not farsighted, when central myopia is fully corrected) — this could eliminate the stimulus for the eyeball to lengthen and potentially slow or stop the progression of myopia in nearsighted children.

Got it? Take a look at the slide show on this page — it will help!

Promising Myopia Control Research

Here are some of the latest research findings about lenses that show promise for controlling myopia in children:

At the 2010 annual meeting of the Association for Research in Vision and Ophthalmology (ARVO), researchers from Australia, China and the United States presented data from a study of experimental myopia-control contact lenses worn by Chinese schoolchildren for six months. The contacts had a special dual-focus design to fully correct central myopia and reduce the hyperopic defocus in the peripheral retina.

All the children were between the ages of 7 and 14 at the beginning of the study and had -0.75 to -3.50 diopters (D) of myopia with no more than 0.50 D of astigmatism. A total of 65 children wore the experimental contacts, and 50 children wore eyeglasses. At the end of the six-month study period, the children wearing the experimental contact lenses had 54 percent less progression of their myopia than the children wearing eyeglasses.

In June 2011, researchers in New Zealand reported on a comparison study of an experimental dual-focus soft contact lens and conventional soft contact lenses for myopia control in children. A total of 40 nearsighted children ages 11 to 14 participated in the study. The children wore the dual-focus lens on one randomly assigned eye (and a conventional soft contact lens on the fellow eye) for 10 months, then switched the lenses to the opposite eye for another 10 months.

In 70 percent of the children, myopia progression was reduced by 30 percent or more in the eye wearing the experimental dual-focus contact lens in both 10-month periods of the study. Visual acuity and contrast sensitivity were essentially the same with the dual-focus lens, compared with the conventional soft contact lenses.

At the 2011 ARVO meeting, researchers from Japan presented a study that investigated whether overnight wear of gas permeable contact lenses designed for orthokeratology (ortho-k) might suppress eyeball elongation in children, which is a factor in myopia progression.

A total of 92 nearsighted children completed the two-year study: 42 wore the overnight ortho-k lenses, and 50 wore conventional eyeglasses during the day. The average age of all children participating was about 12 years at the beginning of the study, and children in both groups had essentially the same amount of pre-existing myopia (-2.57 D) and the same axial (front-to-back) eyeball length (24.7 mm).

At the end of the study, children in the eyeglasses group had a significantly greater increase in the mean axial length of their eyes than children who wore the ortho-k contact lenses. The study authors concluded that overnight ortho-k suppressed elongation of the eyes of children in this study, suggesting the lenses might slow the progression of myopia, compared with wearing eyeglasses.

In 2012, the same researchers published the results of a similar five-year study of 43 nearsighted children that showed wearing gas permeable (GP) ortho-k contacts overnight suppressed axial elongation of the eye, compared with wearing conventional eyeglasses for myopia correction.

Also in 2012, researchers in Spain published study data that revealed children 6 to 12 years of age with -0.75 to -4.00 D of myopia who wore ortho-k contact lenses for a two-year period had less progression of their myopia and reduced axial elongation of their eyes than similar children who wore eyeglasses for myopia correction.

In October 2012, researchers in Hong Kong published yet another study of the effect of ortho-k contact lenses on controlling myopia progression in children. A total of 78 nearsighted children (who were 6 to 10 years old at the beginning of the study, with -0.50 to -4.00 D of myopia) completed the two-year study.

Children who wore the ortho-k lenses had a slower increase in axial length of their eyes by 43 percent, compared with the kids who wore eyeglasses. Also, the younger children fitted with the corneal reshaping contact lenses (some experts prefer this term when the purpose of the specialty GP contact lenses is for myopia control) had a greater reduction of myopia progression than the older children.

Furthermore, as myopia control expert Jeffrey J. Walline, OD, PhD, from The Ohio State University College of Optometry points out in his analysis of the study published in the same issue of Investigative Ophthalmology & Visual Science, the beneficial effect of slowed myopia progression from wearing the corneal reshaping lenses extended beyond the first year of myopia treatment. This has not been true for other myopia control measures, such as atropine eye drops and multifocal eyeglasses (see below).

Other Myopia Control Measures

Efforts to find a myopia cure or a way to slow the progression of nearsightedness in children have been going on for decades.

Besides new contact lenses designed to alter peripheral blur and thereby slow myopia progression, here are other measures that have been investigated over the years:

Atropine eye drops. Of all the methods for myopia control tried so far, the use of atropine eye drops has had the most effective short-term results. But it also has some drawbacks.

Topical atropine is a medicine used to widely dilate the pupil and temporarily paralyze the eye's accommodation (near focusing) mechanism. Atropine typically is not used for routine dilated eye exams because its actions are long-lasting and can take a week or longer to wear off. (The dilating drops your eye doctor uses during your eye exam typically wear off within a couple hours.)

A common use for atropine these days is to reduce eye pain associated with certain types of uveitis.

Because some research has suggested nearsightedness in children may be linked to focusing fatigue, investigators have looked into using atropine to disable the eye's focusing mechanism to control myopia.

And results of the studies of atropine to control childhood myopia have been impressive — at least for the first year of myopia treatment. Four short-term studies published between 1989 and 2010 found atropine produced an average reduction of myopia progression of 81 percent among nearsighted children. However, additional research has shown that the myopia control effect from atropine does not continue after the first year of treatment, and that short-term use of atropine may not control nearsightedness significantly in the long run.

Also, many eye doctors are reluctant to prescribe atropine for children because long-term effects of sustained use of the medication are unknown. Other drawbacks of atropine treatment include discomfort and light sensitivity from prolonged pupil dilation and loss of near focusing ability during treatment, and the added expense of a child needing bifocals or progressive lenses during treatment to be able to read clearly, since his or her near focusing ability is affected.

Gas permeable contact lenses. Whether conventional gas permeable contacts can slow the progression of myopia in children has been a controversial topic for many years. For many eye care professionals, this issue was resolved with the publication of the results of the Contact Lens and Myopia Progression (CLAMP) study in 2004.

Funded by the National Eye Institute, the CLAMP study followed myopia progression in more than 100 children ranging from age 8 to 11 over a three-year period. Some wore rigid GP contact lenses, while others wore soft contact lenses. Many children who wore the GP lenses did show less short-term myopia progression, but it was only temporary.

At the end of the study period, no significant myopia control effect was provided by conventional gas permeable contact lenses.

Multifocal eyeglasses. The use of multifocal eyeglass lenses (bifocals or progressive lenses) also has been investigated as a way to control nearsightedness in children. A number of studies published between 2000 and 2011 found that wearing multifocal eyeglasses does not provide a significant reduction in progressive myopia for most children.

One study, the Correction of Myopia Evaluation Trial (COMET), published in 2003, found that progressive eyeglass lenses, compared with regular single vision lenses, did slow myopia progression in children by a small, statistically significant amount during the first year. But the effect wasn't significant in the next two years.

Undercorrection of myopia. Another technique investigated for myopia control in children is the intentional undercorrection of myopia with glasses or contact lenses. The rationale behind this idea is that undercorrection would reduce near focusing strain that has been suggested as a cause of progressive myopia.

Unfortunately, recent studies show that undercorrection of myopia not only is ineffective at slowing the progression of myopia, it may in fact increase progressive myopia. Also, intentional undercorrection of myopia causes blurred distance vision, which may put a child at a disadvantage in the classroom or in sports and affect their safety.

What About Myopia Control in Adults?

Myopia typically develops during the early school years and tends to progress more rapidly in pre-teens than in older teenagers. This is why myopia control studies usually involve relatively young children.

While it's true that myopia also can develop and progress in young adults, this is less common, and it's possible that an adult's eyes may not respond to myopia control treatments the same way a child's eyes do. For these reasons, it's likely that most research in this area will continue to focus on controlling progressive myopia in children.

Is There a Myopia Cure?

It's important to point out that "myopia control" does not mean curing or reversing myopia.

Researchers who are developing contact lenses for myopia control are not suggesting that these lenses will cure myopia or reverse existing myopia permanently. Orthokeratology and corneal refractive therapy (CRT) contact lenses can reverse limited amounts of myopia, but this correction is temporary if overnight wear of these lenses is discontinued for an extended period.

You no doubt have seen or heard advertisements on television and the Internet for eye exercises or eyeglasses that supposedly will permanently correct your eyesight. My opinion (and the opinion shared by most eye doctors and vision researchers) is that these myopia "cures" are highly suspect and are not supported by well-controlled research. Buyer beware!

For the Latest Myopia Control News

Currently there are no contact lenses that have been FDA approved specifically for controlling progressive myopia. But research is ongoing, and that might change in the near future.

To stay up-to-date on the latest news and developments about controlling nearsightedness in children or a possible myopia cure, visit AllAboutVision.com and type "myopia control" in the search box on our homepage.

About the Author: Gary Heiting, OD, is senior editor of AllAboutVision.com. Dr. Heiting has more than 25 years of experience as an eye care provider, health educator and consultant to the eyewear industry. His special interests include contact lenses, nutrition and preventive vision care. Connect with Dr. Heiting via Google+.

[Page updated February 2013]