True confession: I’ve been wearing glasses since I was 10 years-old. It didn’t bother me to wear glasses because I was so pleased to be able to see the chalkboard clearly. For me, wearing glasses was a simple thing I could do to maintain good grades. Many kids aren’t like me in that they aren’t always happy to wear eyeglasses. One day soon, eyeglasses for myopia in children will be a thing of the past.
A study done at the Ohio State University College of Optometry and funded by the National Eye Institute (NEI), demonstrated that children who wore multifocal contact lenses had a slower progression of myopia. The study, known as Bifocal Lenses In Nearsighted Kids (BLINK), was a three year clinic trial of 287 myopic children who were between the ages of 7 to 11 years-old.
Myopia happens when a child’s eye grows too long from the front to the back. As a result, images of distant objects are focused at a point in front of the retina, instead of on the retina. That leads to poor distance vision. While glasses and contact lenses correct the vision of someone with myopia, those things don’t treat the condition. Multifocal contact lenses, which are used to improve the vision of adults over the age of 40, both correct myopic vision and slowed its progression by slowing eye growth.
How does that happen? The multifocal contact lenses are shaped like a bullseye and they have two parts for focusing light, the center and the outer part. The center of the lens corrects nearsightedness so that the light is focused directly on the retina and a person has clear distance vision. The outer part of the lens adds focusing power to bring peripheral light rays in focus to the front of the retina. Bringing light to focus in the front of the retina was shown in animal studies to cue the eye to slow growth. The higher the power added, the more the front of the retina focuses on peripheral light. In comparison, single vision glasses and contact lenses focus peripheral light to a point behind the retina, prompting the eye to keep growing.
The kids were randomly assigned to wear either wear single vision contact lenses or multifocal lenses. The lenses were either high-add power (+2.50 diopters) or medium-add power (+1.50 diopters). After three years, kids in the high-add multifocal contact lens group had the slowest progression of myopia, as measured by changes in their eye prescription. The high-add group was measured at -0.60 diopters, the medium-add group was measured at -0.89 diopters and the single vision group was measured at -1.05 diopters.
Why go to all this trouble if myopia is corrected with eyeglasses or contact lenses? Having myopia increases the risk of getting cataracts, a detached retina, glaucoma and myopic maculopathy, all of which can lead to a loss of vision. Thankfully this research and others have lead to treatment options for children who are nearsighted. In addition to the multifocal contact lenses, there are contact lenses that reshape the cornea during sleep known as orthokeratology and atropine drops help to correct myopia.
“There is a clear benefit from multifocal lenses at three years, but further study is needed to determine the ideal duration for wearing the lenses,” said Lisa A. Jones-Jordan, Ph.D., principal investigator of the Data Coordinating Center at the Ohio State University. “Researchers will need determine how permanent the prevention of myopia progression will be once children stop wearing the multifocal lenses.” To learn how long children benefit from this treatment, a follow-up study is underway.
Of course, one question remains. How many of the kids in this study were happy to see the chalkboard more clearly?