A new multifocal implantable lens has surpassed the monofocal option and eradicated the need for patients to decide between correcting their farsightedness or nearsightedness and their presbyopia.
"It's the best technology available for spectacle independence," says Price Kloess, MD, medical director of Alabama Vision Center.
The multifocal intraocular lenses (IOL) not only allow clear vision near and far, but in the more complex mid-range vision as well. "We call them smart lenses," Kloess says.
As a precursor to these new multifocal IOLs, Bausch & Lomb released the first generation multifocal lenses in 2003, called Crystalens. "The hope was that it would restore some of the accommodation we lose with age," Kloess says.
In reality, they worked initially, but over time many patients lost the ability to see at near. "Because this technology did not address the primary reason for loss of accommodation, which is failure of the ciliary muscle as we age," Kloess says.
These new lenses have full diffractive and refractive surfaces allowing better natural vision over longer ranges. "They bend the light using concentric rings of increasing lens strength," Kloess says. "They're one solid piece, but they look like bulls-eye targets."
The rings cause the light to remain constant for near and far vision, even as the pupil dilates in low light, so vision in all ranges remains sharp. "Those rings have a power that will cause light to bend and focus various images at various distances on the retina at the same time," he says. "This is basically longstanding telescope research applied to intraocular lenses."
In the last 18 months, two companies have released these new ringed multifocal intraocular lenses: TECNIS by Abbot Medical Optics and reSTOR by Alcon. "It's the optics of this implant that's new. The materials and the basic platform has been around. It's important because it allows excellent centration and stability of the implant," Kloess says.
Kloess sees slight variances between the two lenses. "With ReSTOR you may need pretty good light to read with versus the TECNIS, but it tends to have less glare at night. Overall, patients have excellent results with both."
The implant procedure remains the same with this generation of MIOLs. But these delicate lenses are less forgiving, says Kloess. "These lenses are not tolerant of surgical inaccuracies or ocular pathology, like dry eyes or macular degeneration. And you need a pristine surgery for optimal outcomes."
In cases where a refractive error develops, LASIK can correct it. "If some degree of refractory error remains, we can etch that prescription on the cornea. If over time a refractive drift occurs, we can still correct it with a LASIK-type procedure," Kloess says.
He has had to tweak about eight percent of the 1,300 MIOL implants he's performed. In addition, about five patients have asked to have them removed completely.
Their complaint stems from halos appearing around light sources at night or an overall lack of clarity. "If you question any MIOL patient as to whether they see rings at night, most will say 'yes.' But they say it doesn't cause much of an issue," Kloess says.
Within three to six months, almost all the patients become tolerant of the halos. "No one knows exactly why this process of neuro-adaptation occurs, but clinically it is a real phenomenon" he says.
In that one percent who did not adapt, he removed the MIOL and replaced it with a monofocal implant. Kloess says national surveys quote 5 to 10 percent dissatisfaction with the new lenses.
Though Medicare does not cover the new lenses as part of cataract surgery, they will cover the surgery if the patient pays the additional cost for the lenses.
Kloess thinks he's one of only a handful of eye surgeons in town doing these procedures. "Most people have not caught on to this, because the technology has only been out about a year."
For patients with astigmatism, it's not hopeless. The new ReSTOR TORIC intraocular lens begins FDA clinical trials this month. Kloess' practice, Alabama Vision Center, will serve as one of eight test sites in the U.S.
"It's the next frontier for this technology. It is a multifocal implant that gives visual ranges and corrects a higher degree of astigmatism. It's clearly state of the art," Kloess says.
Another new IOL expected out this summer does expand the correcting power of lenses for those with astigmatism. Alcon's AcrySof Toric IOL will correct astigmatism up to 4.5 diopters versus the old version's 2.5 diopters.
"This opens up a whole other group of patients to spectacle independence," Kloess says. "I have a waiting list of about 50 patients for this new lens. This will be life-changing for them."
Kloess says the multifocal lenses on the market now are also ideal for patients without cataracts but seeking spectacle independence. In this age of handheld devices and computers, patients facing the triple threat of trouble reading, seeing computer screens, and distance vision may eagerly embrace these lenses. "These lenses do best with people 50 years or older and highly motivated to be spectacle independent. It's a great option for them."
