Multifocal contact lenses usually worn by people over 40 could slow the progression of myopia in children as young as seven, a new study suggests.
Compared with single vision contact lenses, the improvement can be as much as 43% over three years, a team from Ohio State University writes in a paper in the Journal of the American Medical Association.
Commonly known as nearsightedness, myopia increases the risk of cataracts, glaucoma and retinal detachment later in life.
It occurs when a child’s developing eyes grow too long from front to back, so images of distant objects are focused at a point in front of the retina, rather than on it. As a result, people with myopia have good near vision but poor distance vision.
Ohio’s Jeffrey J Walline and colleagues say animal studies have shown that bringing light to focus in front of the retina cues the eye to slow growth; the higher the power added, the further in front of the retina it focuses peripheral light.
For their study they used soft multifocal lenses with two sections for focusing light. The centre corrects nearsightedness so that distance vision is clear, and focuses light directly on the retina, while the outer portion adds focusing power to bring the peripheral light rays into focus in front of the retina.
They worked with 287 myopic children, aged seven to 11 years, who were randomly assigned to wear either single-vision contact lenses or multifocal lenses at one of two different levels of power as often as they comfortably could during the day.
After three years, children in the high-add multifocal contact lens group were found to have the slowest progression of their myopia, and the multifocal lenses also slowed eye growth.
“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,” says co-author Lisa A Jones-Jordan.
“Researchers will need determine how permanent the prevention of myopia progression will be once children stop wearing the multifocal lenses.”
A follow-up study with the same children is under way to see if the benefits hold when they go off treatment.
Most importantly, says Walline, it’s “not a problem to fit younger kids in contact lenses”.
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