Multifocal Intraocular Lenses
(ReSTOR, ReZoom, Tecnis)
Recent FDA approvals of newer versions of multifocal intraocular lenses (IOLs) for cataract surgery mean even more options are available for people who want to reduce or possibly eliminate their dependence on eyeglasses.
During cataract surgery, your eye's natural lens is removed and replaced with an IOL. Standard monofocal IOLs probably will give you great distance vision, but you usually would require reading glasses for near vision. Presbyopia-correcting IOLs with multifocal designs, on the other hand, provide vision at multiple distances.
If you are a good candidate for a multifocal IOL and you choose this option, the type your cataract surgeon recommends likely will depend on your unique circumstances, lifestyle and vision correction needs.
Currently in the United States, these three brands of approved multifocal IOLs are available:
- AcrySof IQ ReSTOR (Alcon): Two basic multifocal versions of the AcrySof IQ ReSTOR IOL now are available in the United States. The original non-aspheric version, approved in March 2005, provides a diffractive design, which changes the way light is directed depending on where it falls on the IOL's different zones. This lets your eye achieve focus at multiple distances.
In late 2008, a newer version of the ReSTOR lens was approved. This version has a different near power zone of +3.00 diopters, which enables better vision at intermediate distances. The original version has a +4.00 diopter power that provides better near vision, but with less emphasis on intermediate vision.
- ReZoom (Abbott Medical Optics or AMO): This intraocular lens is an improved version of the old multifocal Array IOL and uses a design with different zones within concentric rings for focusing at varying distances. Previously the ReZoom was considered the strongest multifocal IOL for enhancing intermediate vision, but now it has competition in that area with the release of the newest ReSTOR IOL.
- Tecnis (AMO): Like the IQ ReSTOR, the Tecnis uses a diffractive lens design to direct light in different ways depending on different zones in the lens. Clinical trial results leading to FDA approval in January 2009 demonstrated that having a Tecnis multifocal lens implanted in each eye resulted in 20/25 or better distance vision and 20/32 or better near vision for 93 percent of study participants.*
Another FDA-approved IOL, the Crystalens (Bausch + Lomb), also corrects presbyopia but is not a multifocal intraocular lens. The Crystalens is a monofocal IOL that enables focus at multiple distances by shifting its position in the eye, which provides accommodation.
Examples of new designs of multifocal intraocular lenses currently in studies include various versions of Acri.Tec IOLs that emphasize various zones for near, intermediate and distance vision.
Also, future versions of existing, approved multifocal IOLs may have toric designs for the additional correction of astigmatism. This likely would reduce the need for astigmatism-correcting limbal relaxing incisions, which are crucial to achieve optimal vision with multifocal IOLs.
As an example, Alcon's AcrySof IQ ReSTOR Multifocal Toric intraocular lens was launched outside the United States in September 2010.
The company announced plans to file a pre-market application with the FDA in early 2012 for possible U.S. approval.
Mixing Multifocal and Monofocal Intraocular Lenses
With newer options now available, more cataract surgeons have been considering the option of mixing multifocal intraocular lenses to provide the greatest range of vision. Before new FDA approvals, however, only about 5 percent to 10 percent of cataract surgery patients were considered good candidates for this approach.*
Some cataract surgeons now are "mixing and matching" IOLs through techniques such as combining AMO's Tecnis (near vision emphasis) with the ReZoom (intermediate vision emphasis). Another option is to use the new AcrySof IQ ReStor to enhance intermediate vision in one eye and the original version of the ReSTOR to provide stronger near vision in the other eye.
During one late 2008 conference* Richard L. Lindstrom, MD, said at least 11 different options were available for cataract surgeons to consider when mixing and matching IOLs including the combination of multifocal IOLs with standard monofocal IOLs.
Monovision can be provided with standard monofocal IOLs by adjusting one eye for near vision and the other for distance vision. However, Dr. Lindstrom said this approach can lead to development of a type of amblyopia or "lazy eye," when an eye adjusted for near vision loses ability to see in the distance. Also, monovision with single vision IOLs can affect the ability of eyes to work together smoothly, called stereopsis.
With a modified monovision or "blended" approach to mixing two different multifocal IOLs, Dr. Lindstrom said stereopsis can be maintained and amblyopia avoided because both eyes maintain the ability to achieve focus at multiple distances even when one eye has a near vision emphasis and the other eye has an intermediate or distance vision emphasis.
Dr. Lindstrom reported the results of one Brazilian study of multifocal IOLs and percentages of those who achieved independence from eyeglasses:
- ReZoom/ReZoom: 75 percent
- ReSTOR/ReSTOR (original versions): 89 percent
- ReZoom/ReSTOR: 100 percent
- ReZoom/Tecnis: 100 percent
These studies do not factor in availability of the newly released version of ReSTOR, which enhances intermediate vision helpful for working at a computer. Visual distortions in the above study were highest in the ReZoom/ReZoom combination and lowest in the ReZoom/Tecnis combination.
Also, for every study that supports the mix-and-match approach, another can be found that dismisses the technique outright in favor of balanced, equal vision from implantation of the same IOL in both eyes. Therefore, mixing multifocal IOLs is an approach you should not take lightly and that you should discuss in-depth with your cataract surgeon.
What You Should Know Before Considering a Multifocal IOL
Many cataract surgeons exchanging ideas in trade journals indicate that an extreme perfectionist is the very worst kind of candidate for a multifocal or presbyopia-correcting intraocular lens of any kind. While these lenses are high tech marvels, they are unlikely to produce absolutely crisp vision at multiple distances at all times and in all circumstances.
Particularly with multifocal IOLs, you must be prepared for the possibility of at least some visual distortions particularly in the form of glare and halos around light sources at night. These distortions rarely would prohibit night driving. But they are prevalent enough that most cataract surgeons would advise against multifocal IOLs for anyone in a profession requiring great night vision, such as truck drivers.
Top: ReSTOR and ReZoom. Bottom: Tecnis.
Other reasons you may be eliminated as a candidate for multifocal IOLs include:
- A high level of astigmatism that cannot be corrected easily with limbal relaxing incisions or refractive eye surgery.
- Other eye problems, such as retinal diseases, which would reduce the quality of your vision.
- Near perfect vision (emmetropia), except for presbyopia, prior to cataract surgery. This may sound odd. But people who have enjoyed great vision all their lives tend to find any kind of visual distortion related to multifocal IOLs unacceptable.
- People with only low to moderate degrees of myopia. Again, vision improvements for people in this category may not be significant enough to make up for the possible tradeoff of certain visual distortions associated with multifocal IOLs.
Good candidates for multifocal or presbyopia-correcting IOLs generally are easy-going, realistic in their expectations and willing to accept a few tradeoffs, such as some visual distortions, in exchange for reduced dependency on eyeglasses or the possibility of eliminating them altogether.
Other factors that help cataract surgeons identify good candidates for multifocal IOLs include:
- Younger cataract patients with good general eye health and active lifestyles that would inspire them to reduce or eliminate their need for eyeglasses.
- People who have presbyopia and near vision problems caused by hyperopia. They tend to have the very best outcomes with multifocal IOLs because of better focusing ability. They also appreciate the near vision improvement they are likely to receive.
- People with high to severe levels of myopia. These types of candidates are so accustomed to extremely blurry vision without eyeglasses that the uncorrected vision improvement with multifocal IOLs, even with some visual distortions, can be extremely dramatic and appreciated.
Optimal performance of a multifocal IOL also may depend on where the center of a lens optic is located relative to the center of the pupil, according to cataract and refractive surgeon Robert L. Epstein, MD, director of the Mercy Center for Corrective Eye Surgery near Chicago.
"Since a person's pupil is not necessarily perfectly concentric with the center of the lens capsule, it is possible that the patient's vision may be improved with a brief office laser procedure to slightly change the position of the center of the pupil," Dr. Epstein said.
He noted past weaknesses of earlier versions of presbyopia-correcting intraocular lenses that currently are approved: near vision problems with the accommodating Crystalens, night glare problems with the ReZoom and weakness in the intermediate distance range with the ReSTOR.
"With each lens, newer modifications appear to be addressing these points, and results have further improved," Dr. Epstein said.
Because changes can occur later in the eye and with the implant, Dr. Epstein said it's important to visit your eye surgeon for periodic vision assessments after your cataract surgery.
"Implant-related changes as well as changes in other parts of the eye the peripheral retina, the macula and the optic nerve all can have an impact on vision," he said. "Detection and treatment of these issues can be very important."
If you do choose a multifocal IOL, you also must be aware of the cost of cataract surgery involving premium lenses. While most Medicare and private insurance will cover basic cataract surgery costs, you still will need to pay out-of-pocket the extra price of "premium" IOLs that are considered cosmetic and not medically necessary. These costs can be as high as $2,500 per eye.
Follow your cataract surgeon's advice about which presbyopia-correcting IOL you should use (if any). If your eye surgeon is not experienced with this type of "premium" IOL and you are interested in pursuing the idea, you might ask for a referral.
[Learn why an AllAboutVision.com editorial board member and former cataract surgeon decided against presbyopia-correcting IOLs for his own cataract procedure. And learn why our editor chose to mix multifocal IOLs for her cataract surgery. Although choices and circumstances differed, both people reported good outcomes.]
*Presentations at the November 2008 American Academy of Ophthalmology conference in Atlanta.
Gary Heiting, OD, also contributed to this article.
[Page updated April 2013]
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