Laser surgery - for example, LASIK -- is the standard procedure for nearsighted people who don't want to depend on glasses or contact lenses. It strips off cells from the cornea, the clear tissue covering the eye, thereby flattening it and allowing visual input to come into focus on the retina.

In extremely nearsighted people, however, laser surgery isn't practical because too much tissue would have to be removed. So doctors may choose to insert plastic lenses in front of the eye's natural lens instead.

Such lenses, known as phakic intraocular lenses, were only approved by the U.S. Food and Drug Administration in 2004, and until now no one had systematically reviewed the studies testing them against laser surgery.

The new report, published in the Cochrane Database of Systematic Reviews, shows that implantable lenses - which, at $3,000-$5,000 per eye, cost about double what laser surgery does -- may have advantages over laser surgery.

Laser surgery becomes less predictable and less safe for very shortsighted people, said Dr. Allon Barsam of the Moorfields Eye Hospital NHS Foundation Trust in London, who led the research.

There is now evidence to show that intraocular lenses are safer than laser surgery in people with moderate and high levels of nearsightedness, he told Reuters Health.

Barsam found three studies in which 132 patients with moderate to high-level nearsightedness had been randomly assigned to receive either laser surgery or intraocular lenses.

One year after the surgery, the number of patients who had 20/20 visual acuity without glasses was similar for the two kinds of surgery.

But patients with lens implants had better contrast sensitivity and clearer spectacle-corrected vision. They also reported better quality of vision and were more satisfied with the surgery than those who had undergone a laser procedure.

The researchers did note that the quality of the available research was poor, and that long-term risks are still unknown. One patient developed cataracts after two years, for instance, although a new lens successfully restored 20/20 vision.

Still, they conclude that implantable lenses are worth considering for less severe cases of nearsightedness than is standard now.

Other experts say this might be an unwise move, because cutting into the eye to insert a lens carries bigger risks than laser surgery, including retinal detachment and infections.

If I can do laser surgery, I will do it, said Dr. Richard Duffey, an eye surgeon at Premier Medical Eye Group in Mobile, Alabama, who was not involved in the new research.

He has done surveys among his colleagues for more than a decade, and said most share his preference for the less-invasive laser surgery.

The absolute vast majority of surgeons in the U.S. are going to reserve intraocular lenses for very nearsighted patients, he told Reuters Health. When you start talking about intraocular procedures you are now adding a whole new layer of risks.

Medicine