As scientists try to untangle the reasons for skyrocketing rates of nearsightedness in kids, new treatment options can help prevent their vision from getting worse.
The number of children who need glasses to see far away objects—a condition known as myopia—is increasing and current projections suggest that by 2050, 50 percent of the world’s population will be affected.
In the 1970s, 25 percent of Americans had myopia; but just three decades later prevalence rose to 42 percent. Although genetics is responsible for some cases of myopia, scientists now believe that environment also plays a major role. Now researchers are starting to untangle the reasons for the skyrocketing rates and devise ways of slowing down and reversing a child’s declining vision—which is important for their overall quality of life and their risk for developing vision loss later in life.
“Kids are becoming nearsighted at rates that are faster than we’ve ever seen before,” says Nick Onken, an optometrist at the University of Alabama, Birmingham. “It’s faster than even genetics alone can account for.” “We’ve known for decades that the more nearsighted the person is,” says Onken, “the higher the likelihood they are for losing vision when they’re older, due to conditions like retinal detachment, glaucoma, macular degeneration and cataracts.”
What happens to the eye with myopia
Myopia often starts during childhood, due to a mismatch between how fast the eye is growing and where light is focusing on the retina.
“The condition of myopia or nearsightedness is caused by the fact that the eye is too long,” says Carolyn Lederman, an ophthalmologist based in Purchase, New York. When the entire eyeball grows longer than it should, this creates a situation where the focusing components of the eye—the cornea and the lens—target light just in front of the retina, rather than on the retina, which causes far-away objects to appear blurry. As it turns out, the age at which a child first becomes myopic is often predictive of how bad their vision will end up.
“The biggest predictor of how nearsighted you’re going to be, is when you become nearsighted,” says Jeffrey Walline, an optometrist and associate dean of research at The Ohio State University. As Walline explains, the younger a child is when they first become nearsighted, the worse it will end up as, due to the length of time that the eyeball spends growing longer than it should. For most children, their vision will stabilize during their late teenage years, although for a minority of individuals, this process will last until their mid-20s.
In addition to needing corrective glasses or contacts to see properly, people with myopia are also at a much higher risk for developing vision problems later in life. As Ann Shue, an ophthalmologist at Stanford University, explains, when the eye is just a little bit bigger than it should be, this stretches it out, similar to pizza dough, which can affect the very delicate nerves and blood vessels of the retina that are attached to the back of the eye. “As we get older, that can pull on the retina,” causing issues such as glaucoma, retinal detachment or macular eye degeneration, Shue says.
Myopia rates are increasing
Although the reasons for the increasing rates are complicated, and there are likely to be a number of factors that are contributing, a number of studies consistently point to a lack of outdoor time as being one of the major risk factors for developing myopia.
One theory for the connection between a lack of outdoor time and an increased risk for developing myopia is the effect of outdoor light on stimulating the release of dopamine, which acts as a signal to slow eye growth. “Brighter light releases more inhibition of eye growth,” which prevents the eye from growing too long, says Ian Morgan, a professor at Australia National University, whose research focuses on myopia.
What is less clear is the effect of screen-time and near-work—such as reading—on the risk for developing myopia. “These rates of myopia going up started before the first iPhone was introduced,” says David Bernsten, an optometrist at the University of Houston, whose research focuses on myopia. Some studies suggest that screen-time and near-work are linked to a greater risk of developing myopia, while other studies don’t show a link.
Severity can be reduced
To explore whether there were interventions could slow vision changes, researchers launched the BLINK study in which 294 children between the ages of 7 to 11 received contacts lens—some regular, single-vision contact lens, some bifocal—which have been shown in previous studies to slow down the progression of myopia. (Both Bernsten and Walline were involved in the BLINK study.)
These special contact lens, which are usually prescribed to older patients who need bifocal glasses, focus most of the light on the retina, giving the wearer clear central vision, while also causing a small amount of light in the peripheral vision to focus just in front of the retina. This slight blurring of the peripheral vision seems to act as a signal to the eye to slow its growth. “I didn’t notice anything hugely different [about my vision],” while wearing these contacts, says Katie Krueger, a junior at Lee University in Cleveland, Tennessee, who was a participant in the BLINK study. The fact that she didn’t detect a difference indicates her vision was fully functional with the contacts.
For Krueger, although her vision worsened a little over the next few years, it eventually stabilized, leaving her with mild myopia.
In other studies, daily use of a special eye drop, called low-concentration atropine, has been shown to also slow the progression of myopia. At regular concentrations of about 1 percent, atropine is used to dilate the pupil for eye exams. But at very low concentrations, usually between 0.01 to 0.05 percent solution, atropine drops just before bed has been shown to slow the growth of the eyeball. At this time however, there are still questions about which dose is the most effective, and whether the effectiveness varies for different children. Although the details are still being fine-tuned, it’s a promising treatment.
“Using either of those treatments appears to slow down the rate of the growth of the eye by about 50 to 60 percent,” Onken says. “We can’t bring the train to a stop, but we can slow it down.”
Stopping myopia before it develops
Researchers are starting to come up with ways to stop the progression of myopia before it starts. To do this, they are trying to predict which children will develop myopia. “The fastest eye growth is actually just before you become nearsighted,” Walline says.
Walline, along with collaborators, are working on setting up clinical trials to either prevent or delay the onset of myopia in children, using low-dose atropine eye drops. This study will be similar to others that have been conducted in the past, outside the United States, which show that low-dose atropine eye drops can delay the onset of myopia in children. Then, if a child does develop myopia, the treatment for slowing it down is the same as it is for preventing its onset.
One day, the goal is to be able to offer these options to all children who are at risk of developing myopia. “This has huge benefits just in terms of practical living and huge benefits in terms of the potential long-term consequences,” Morgan says. “I think we’ll see over the next 10 years this will just become standard, optometrical practice.”