Controlling Nearsightedness in Children
Myopia (nearsightedness) is a common vision problem affecting children who can see well up close, while distant objects are blurred. Nearsighted children tend to squint to see distant objects such as the board at school. They also tend to sit closer to the television to see it more clearly.
Sometimes, childhood myopia can worsen year after year. This change can be disconcerting to both children and their parents, prompting the question: "Will it ever stop? Or, will this get so bad that, someday, glasses won't help?"
Myopia that develops in childhood nearly always stabilizes by age 20. But by then, some kids have become very nearsighted, leading scientists to search for ways to slow down the progression of myopia in children. Four possible treatments that show promise include orthokeratology ("ortho-k"), atropine eye drops, multifocal eyeglasses, and soft multifocal contact lenses.
Orthokeratology, or "ortho-k," is the use of specially designed gas permeable contact lenses to flatten the shape of the cornea and thereby reduce or correct mild to moderate amounts of nearsightedness. The lenses are worn during sleep and removed in the morning. Though temporary eyeglasses may be required during the early stages of ortho-k, many people with low to moderate amounts of myopia can see well without glasses or contact lenses during the day after wearing the corneal reshaping lenses at night.
Recent research suggests ortho-k may also reduce the lengthening of the eye itself, indicating that wearing ortho-k lenses during childhood may actually cause a permanent reduction in myopia, even if the lenses are discontinued in adulthood.
Topical atropine is a medicine used to dilate the pupil and temporarily paralyze accommodation and completely relax the eyes' focusing mechanism. Because 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.
The results of these studies have been impressive. 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.
Some evidence suggests wearing eyeglasses with bifocal or progressive multifocal lenses may slow the progression of nearsightedness in some children. The mechanism here appears to be that the added magnifying power in these lenses reduces focusing fatigue during reading and other close work, a problem that may contribute to increasing myopia.
A five-year study published in Investigative Ophthalmology & Visual Science produced an interesting result involving nearsighted children whose mother and father were also nearsighted. These children, who wore eyeglasses with progressive multifocal lenses during the course of the study, had less progression of their myopia than similar children who wore eyeglasses with regular, single vision lenses.
Soft Multifocal Contact Lenses
New research shows that multifocal contact lenses also may be an effective myopia control treatment, potentially more so than multifocal eyeglasses. A recent study by researchers at Ohio State University found that wearing multifocal contact lenses reduces the rate of progression of myopia in children by 50%.
One potential reason why multifocal contact lenses may limit progression is that these lenses appear to reduce the lengthening of the eye, which leads to increasing myopia over time.
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