Implantable Lenses: Help for Severe Myopia
2 Types of Implantable Lenses continued...
A myopia correction from -3 diopters to -16 diopters.
A myopia reduction from -16 diopters to -20 diopters.
Neither lens treats astigmatism, an eye problem that often accompanies nearsightedness. So you must have astigmatism of 2.5 diopters or less to be a candidate for these two lenses.
There are other phakic implantable lenses used in Europe that can treat both myopia and astigmatism, but they have not yet been approved by the FDA for use in the U.S.
Implantable Lens Pros and Cons
"The Verisyse lens is not foldable, so it has to go in through a large incision. And that's a negative," says D. Rex Hamilton, MD, FACS, director of the UCLA Laser Refractive Center. "It also clips on the iris, and sits in front of the iris, so it's closer to the inner surface of the cornea." This means that there is a slightly higher risk of damage to the cornea, which can lead to the need for a corneal transplant.
The Visian lens is foldable, so it can be inserted through a smaller incision that usually requires no sutures. But because it sits close to the natural lens of the eye, it can cause cataracts in a small percentage of people, says James J. Salz, MD, clinical professor of Ophthalmology at the University of Southern California. "And we don't know how many patients will get a cataract if they've had that lens in their eye for over 10 years." The Visian lens has been modified recently to decrease the risk of cataracts.
Also, as with any surgery, both implantable lenses pose a small risk of infection, which in rare cases could cause blindness.
In clinical trials, both brands corrected vision well. With the Visian lens, 95% of patients had 20/40 or better vision, the level needed to obtain a driver's license, and 59% had 20/20 or better after three years. With the Verisyse lens, 92% had 20/40 or better vision, and 44% had 20/20 or better after three years.