Hard Contact Lenses Slow Kids' Nearsightedness
Soft, Hard Contacts Compared in 3-Year Study
Dec. 13, 2004 -- Nearsightedness progresses more slowly in children who wear hard contact lenses compared with those who wear soft contact lenses, say Ohio researchers.
About a quarter of the U.S. population is nearsighted. The problem, called myopia, usually starts between ages 8-16 years. It can worsen with time, but it usually stops progressing in the mid-teens for women and the mid-20s for men.
Most forms of nearsightedness can be managed with corrective lens. Yet controlling the progression of myopia can have many benefits, say the researchers. In past studies, hard contact lenses (rigid, gas-permeable lenses) have appeared to slow down nearsightedness. But other research on children contradicts that, says Jeffrey Walline, OD, PhD, of The Ohio State University College of Optometry.
In an attempt to settle the matter, Walline and colleagues designed their own study. They recruited 116 kids who were about 10 years old at the start of the three-year project. All participants had 20/20 vision (with correction) when the study began.
With their parents' permission, the children were randomly assigned to wear either hard or soft contacts for three years. The researchers also allowed a "run-in" period to make sure the kids could adjust to the hard contacts.
All the kids had their vision checked at the study's start and virtually all had annual eye exams. Only four kids missed one of the yearly tests. About 87% wore their originally assigned lenses to the tests.
Nearsightedness progressed almost 29% more slowly in the hard contacts group compared with the soft contacts group.
All the kids' corneas flattened as they adjusted to their lenses, but corneal curvatures returned to normal in the hard contacts group by the study's end.
That wasn't true for the soft contacts group. The corneal curvatures in those children steepened, which is consistent with progression of nearsightedness.
The findings are reliable and informative, but nearsighted kids shouldn't automatically choose hard contact lenses, say the researchers. They say that the slowed progression of nearsightedness may not be significant enough.
The benefits may stem from corneal flattening, which may be reversible. It's not known if the effects are permanent, say the researchers.
The study appears in the December issue of the Archives of Ophthalmology.