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July 13, 2009 -- A new type of implantable contact lens may offer an alternative to glasses or regular contacts for people with moderate to severe nearsightedness (myopia).
The first long-term study of the implantable lenses made of a collagen-like polymer substance shows they were safe and effective at correcting myopia in the majority of recipients for up to four years.
Researchers say laser eye surgery (laser-assisted in-situ keratomileusis or LASIK) has gained widespread popularity for the correction of myopia. But people with severe nearsightedness or thin corneas aren’t ideal candidates for the treatment because of the risk of keratectasia, an abnormality of the cornea. ?
Unlike LASIK, the implantation procedure for the new lenses, known as Visian implantable Collamer lenses or ICLs, is largely reversible and the lens is interchangeable. But previous studies of the lenses have reported complications such as cataracts, loss of cells lining the eye, and glaucoma from the implantable lenses.
In this study, published in the Archives of Ophthalmology, researchers assessed the safety and effectiveness of the implantable lenses in 56 eyes of 34 people with moderate to severe myopia who had the procedure in Japan.
Four years after the surgery, 79% of the eyes were within 0.5 diopter (the unit that measures lens power) of the targeted correction and 93% were within 1 diopter.
Researchers say the collagen polymer lens also performed well in terms of safety, predictability, and stability in people with high myopia throughout the four-year follow-up.
“In addition, no vision-threatening complications occurred throughout the follow-up period,” writes researcher Kazutaka Kamiya, MD, PhD, of the University of Kitasato School of Medicine in Kanagawa, Japan, and colleagues. They say the new implantable lens “may be a good alternative for the treatment of moderate to high myopia. More prolonged careful observation for longer than four years is necessary to assess late-onset complications of this surgical technique.”