implant to correct eyesight

FDA advisors back new implant to correct eyesight

TINY, transparent rings implanted onto the cornea may help correct mild to moderate

nearsightedness without glass-

es or contact lenses, offering

an alternative to popular but irreversible laser surgery and costing about the same. The US government is considering whether to let Kera Vision Inc.’s Intacs sell as an alternative to highly popular eye surgery. The key difference is while eye surgery is permanent, the implants’ effects seem reversible in most cases because they don’t destroy eye tissue.

“There’s no eraser at the end of a laser,” Dr Marian Macsai, an ophthalmologist at West Virginia university said. “This is removable - take it out if there’s a problem”. Macsai and fellow advisors to the Food and Drug Administration (FDA) voted unanimously to allow Intacs - transparent crescents about as thick as contact lenses that form a ring around the edge of the cornea - to be sold. But they stressed that patients must be warned that removing the implants usually - but not always - helps if patients suffer side effects or are dissatisfied with their resulting vision. “It’s largely reversible,” Dr James McCulley, panel chairman of the University of Texas South western Medical Centre said.

“But it’s not an absolute certainty”. The FDA is not bound by its advisors’ recommendations but typically follows them. If approved, Intacs would cost about the same as laser surgery for nearsighted ness, $U52,200 ($A3,476.66) per eye. Made of the same materials as lenses implanted during cataract surgery, Intacs would come in three thicknesses, for different degrees of mild to moderate near sightedness. Nearsightedness - poor distance vision - occurs when a person’s cornea is too steeply curved. Flattening the cornea, the membrane that covers the front of the eye, helps correct nearsight edness. In radial keratotomy, surgeons slice the cornea with a knife.

or laser surgery, which shaves the cornea to flatten it. But those surgeries can be risky,

sometimes causing problems

with night vision, glare, see

ing halos or blurry vision. Patients occasionally cannot see as well after surgery as before. Most patients who choose these operations do so because they are severely nearsighted. With Intacs, the implant’s slight weight flattens the cornea. KeraVision will be mar keted to some 20 million mildly to moderately near-sighted Americans - whose vision ranges from 20/40, where it’s OK to drive but a movie is blurry without glasses, to 20/200, where patients can barely see the big “E” at the top of eye charts.

In a year-long study of 449 pairs of eyes, 97 per cent had 20/40 vision or better without glasses or contact lenses after the implant.

About 74 per cent had 20/20 or better vision without glasses, and 53 per cent could see 20/16 - the sharper vision that chief investiga tor Dr David Schanzlin of the University of California, San Diego, said is required of combat pilots. Most patients achieved good vision a day after surgery. Some seven per cent to 17 per cent of patients suffered side effects similar to laser surgery, including glare, halos and problems with night vision.

About five per cent of patients had their implants removed. That included 14 patients dissatisfied with their vision correction and 16 who had visual side effects; some were in both categories. Removing the implant corrected more than 80 per cent of those side effects, the company said. Patients get anaesthetic eye drops to numb the eye, but remain awake during the procedure. The doctor clamps the eye lid open, cuts a tiny pocket into the cornea and uses a special device to slip the crescents onto the cornea. A single stitch closes the wound.

It takes about 15 minutes. About 15 per cent of patients report some pain and as with any surgery, infection is also a risk. (AP) ■