For those who have to wear glasses or contact lenses to correct near-sightedness, a new type of surgically implanted contact lens may offer an alternative.
The lenses are made of a collagen-like polymer substance. They are inserted into the eye through a tiny incision and placed in front of the eye's natural lens.
The lens can be removed or exchanged and, unlike laser eye surgery, the procedure can be reversed.
The collagen polymer lenses are also suitable for people with severe nearsightedness or thin corneas. Such patients aren't considered good candidates for LASIK vision correction surgery because they may develop keratectasia, an abnormality of the cornea.
Previous studies of implantable lenses have reported complications such as cataracts, loss of cells lining the eye, and glaucoma.
But a new study, published this week in the Archives of Ophthalmology, found that a brand of implantable lens, called the Visian implantable Collamer lens, or ICL, was safe and effective at correcting myopia in most patients for as long as four years.
For the study, researchers led by Dr. Kazutaka Kamiya of the University of Kitasato School of Medicine in Kanagawa, Japan, assessed the safety and effectiveness of the implantable lenses in 56 eyes of 34 people with moderate to severe myopia.
Four years after surgery, 79 per cent of the eyes were within 0.5 diopter (unit of measuring lens power) of the targeted correction. As well, 93 per cent were within one diopter.
The authors write that lens implantation results were "good in all measures of safety, efficacy, predictability and stability for the correction of high myopia throughout the four-year follow-up."
"In addition, no vision-threatening complications occurred throughout the follow-up period," they write.
The authors say this is the longest study yet to assess the outcomes and side effects of the implantable lenses in nearsighted patients.
One of the co-authors, Dr. Shimizu, reported having been a consultant to STAAR Surgical Company, the maker of the Visian implantable Collamer lens.
The authors say more studies involving "prolonged careful observation for longer than four years" are needed to assess whether there are any long-term complications of the surgery and the lenses themselves.
