Intraocular Lens Implant (IOL)

Intraocular lenses, or IOLs, are the artificial lenses that replace the eye's natural lens that is removed during cataract surgery. IOLs have been around since the mid-1960s, though the first FDA approval for one occurred in 1981. Before that, if you had cataracts removed, you had to wear very thick eyeglasses or special contact lenses in order to see afterward, since the natural lens that had been removed wasn't replaced with anything.

Until recently, only cataract surgeons - not their patients - weighed the risks and benefits of various IOLs. The surgeons' discussions focused on the surgical technique (clear cornea, small incision, etc.) and the physical design of the lenses (one-piece vs. multipiece, acrylic vs. silicone) and how that design affected insertion, positioning and healing.

Good vision after cataract surgery was another important consideration, but now that new IOLs have been introduced that solve more vision problems than ever, cataract surgeons have more to consider before choosing IOLs for their patients' visual needs. Cataract patients are becoming more involved in the choice as well.

If you or someone you know will be undergoing cataract surgery, read the following summary of the most recently developed IOLs.

Multifocal IOLs and Accommodating IOLs:

AcrySof ReStor, Tecnis, ReZoom and Crystalens

Traditional IOLs are monofocal, meaning they offer vision at one distance only (far, intermediate or near). They are definitely an improvement over the cataractous lens that is replaced during surgery, which provides only cloudy, blurred vision at any distance. But traditional IOLs mean that you must wear eyeglasses or contact lenses in order to read, use a computer or view objects in the middle distance, especially if you are already experiencing presbyopia before cataract surgery.

The new multifocal and accommodating IOLs offer the possibility of seeing well at more than one distance, without glasses or contacts. Here are a few examples (note: this is not a complete list):

Stasior
Left: ReStor      Right: ReZoom

 AcrySof ReStor (Alcon) uses apodized diffractive technology - a design that responds to how wide or small the eye's pupil might be - to provide near, intermediate and distance vision. In early 2007, an aspheric version of the AcrySof Restor received FDA approval. Aspheric lenses, because they are somewhat flat near the edges, are thought to improve contrast sensitivity and provide better night vision than other types of multifocal IOLs.

Clinical studies used to support the March 2005 FDA approval showed that 80 percent of people who received the lens didn't use glasses for any activities after their cataract surgery; 84 percent who received the lens in both eyes had distance vision of 20/25 or better, with near vision of 20/32 or better.

Stasior
Tecnis

 The Tecnis Multifocal IOL (Advanced Medical Optics or AMO) is a diffractive artificial lens with specific zones that provide near, intermediate and distance vision. Company officials say the lens has a proprietary design to enhance vision at all distances without depending on the size of the pupil as it expands in low light or constricts in bright light. The Tecnis also is shaped to correct for certain higher-order aberrations, which helps improve ability to see contrasting objects, particularly at night.

AMO reported a 95 percent patient satisfaction rate in clinical trials leading to FDA approval in early 2009.

ReZoom (Advanced Medical Optics) is a multifocal refractive IOL that distributes light over five optical zones to provide near, intermediate and distance vision. The first version of this multifocal IOL was brought to the U.S. market in the late 1990s; the ReZoom is the second-generation version and was FDA-approved in March 2005

In a European study of 215 patients, 93 percent of ReZoom recipients reported never or only occasionally needing glasses.

Crystalens is designed to move within the eye, to provide focusing at all distances.

Crystalens (Bausch & Lomb) gained FDA approval in late 2003, when the IOL was marketed by eyeonics. Bausch & Lomb acquired Crystalens in early 2008, and a newer version of the IOL, known as Crystalens HD, was FDA-approved in late June 2008. Crystalens was designed to restore the eye's accommodation ability, which is gradually reduced as presbyopia progresses. In FDA studies, about 80 percent of people who received the Crystalens HD could see at J2 or better (near vision equivalent of 20/20) after four months - superior to standard IOLs. As with multifocal IOLs, distance vision with the Crystalens tends to be very good.

"Accommodation" is the ability of the eyes to change focus from near to far, far to near and all distances in between. With presbyopia, which usually begins at around age 40, the eye muscle that accomplishes this accommodation - the ciliary muscle - has more difficulty in doing its job, because the eye's lens is becoming less flexible. The ciliary muscle contracts in its effort to move the lens forward, bending it slightly for close-up focusing; but the lens resists because it is not as flexible as it was when the eye was younger.

Since Crystalens has hinges on both sides of the IOL, it can be moved more easily by the ciliary muscle, allowing the eye to focus more naturally at a greater range of distances than traditional IOLs. So far, Crystalens is the only accommodating IOL that has been approved by the FDA, though others are in development.

Synchrony (Visiogen Inc.) is another accommodating IOL that was not FDA-approved as of mid-2008, although company officials have commented that they expect approval possibly in 2009. The lens has regulatory approval in Europe and other locations. This dual-optic IOL has shown promising early results. The Journal of Cataract and Refractive Surgery in January 2007 reported results of a small study showing that the IOL demonstrated ability to restore focus at a range of 1.00 to 5.00 diopters, about twice that of a control group.

It's important to note that you can't be 100 percent certain of seeing well without eyeglasses or contact lenses after cataract surgery, even if your eyes have received multifocal or accommodating IOLs. Some of the factors that can decrease satisfaction with these IOLs include pre-existing astigmatism, incorrect positioning of the IOLs in the eye and nighttime halos that some patients have experienced.

But even with these risks, these new IOLs do provide the probability of good vision without total dependence on eyeglasses or contacts. You may even achieve good vision without using these aids at all.

Monovision

If your cataract surgery involves both eyes, you might consider monovision. This involves implanting an IOL in one eye that provides near vision and an IOL in the other eye that provides distance vision. Usually people can adjust to this, but if you can't, your vision may be blurred at both near and far. Another problem is that depth perception may decrease because there is less binocular vision - your eyes aren't working together as they once did.

The people who do best with this method are those who are already used to monovision with contact lenses, which is a common way of correcting presbyopia. If you can't adjust to monovision after your cataract surgery, you may wish you had tried a multifocal or accommodating IOL instead. Some surgeons will trial-fit a cataract patient in monovision contact lenses prior to inserting monovision IOLs.

Toric IOLs for Astigmatism

Toric IOLs are designed to correct astigmatism. The Staar Surgical Intraocular Lens was the first toric IOL available in the United States; it was FDA-approved in 1998. The Staar toric IOL comes in a full range of distance vision powers, in two versions: one corrects up to 2.00 diopters and the other corrects up to 3.50 diopters of astigmatism.

The FDA approved the AcrySof Toric IOL by Alcon in September 2005.

Most surgeons who treat astigmatism in their cataract patients tend to use astigmatic keratotomy (AK) or limbal relaxing incisions, which involve making incisions in the cornea. But in addition to or even instead of corneal astigmatism, some people may have lenticular astigmatism, caused by irregularity in the shape of the natural lens capsule. This can be corrected with a toric IOL. Risks include poor vision due to the lens rotating out of position, with the possibility of further surgery to reposition or replace the IOL.

Aspheric IOLs

Traditional IOLs are spherical, meaning the front surface is curved. Aspheric IOLs, first launched by Bausch & Lomb in 2004, are slightly flatter in the periphery and are designed to provide better contrast sensitivity. The Bausch & Lomb offering is called the SofPort Advanced Optics IOL. Aspheric IOLs are available also from Alcon, including the AcrySof SN60WF that includes the blue light-blocking feature discussed below and the aspheric version of AcrySof ReStor. Advanced Medical Optics offers the Tecnis Z9000.

There is some debate as to how long this contrast sensitivity benefit can last in older patients. After the period of cloudy, blurred vision that most cataract patients must endure before their surgery, improved contrast sensitivity is indeed a blessing. But since the ganglion cells of the retina are a major determinant of contrast sensitivity and we gradually lose these cells as we age, over time the contrast sensitivity will decrease as well. However, younger people are undergoing cataract surgery now, and this group is likely to have more and healthier ganglion cells. So they would be able to enjoy the better contrast sensitivity for a longer time.

In May 2004, the Tecnis Z9000 aspheric IOL received FDA approval for new labeling that says it can reduce postoperative spherical aberrations and therefore improve the ability to see in varying light conditions such as rain, snow, fog, twilight and nighttime darkness. The approval was based on a clinical study that measured night driving simulator performance in cataract surgery patients. According to manufacturer Advanced Medical Optics, the Tecnis IOL was designed using wavefront analysis of human corneas. Wavefront is the same tool that is used to plan personalized custom LASIK procedures to reduce higher-order aberrations in the visual system.

In March 2007, Bausch & Lomb's SofPort Advanced Optics IOL received a "new technology" designation from the Centers for Medicare and Medicaid Services, enabling extra reimbursement of $50 per lens because of demonstrated ability to reduce spherical aberrations. AMO's Tecnis IOL received a similar designation allowing extra Medicare reimbursement in February 2006.

Blue Light-Filtering IOLs

AcrySof Natural filters both ultraviolet (UV) and high-energy blue light, both of which are present in natural and artificially produced light. UV rays have long been suspected to cause cataracts and other vision problems, and many IOLs filter them out just as your natural crystalline lens does before its removal in cataract surgery. Blue light, which ranges from 400 nm to 500 nm in the visible light spectrum, may cause retinal damage and play a role in the onset of age-related macular degeneration.

The AcrySof Natural is colored a transparent yellow in order to filter the blue light; actually, the color is similar to that of the natural crystalline lens, so the idea behind the AcrySof Natural is to re-add the protection against blue light that is lost when the natural lens is removed. According to Alcon, the manufacturer, the yellow tint doesn't alter the color of your environment or your vision quality.

"Piggyback" IOLs

If you have a less than optimal result from the original intraocular lens used in your cataract surgery, your eye surgeon might discuss with you the option of inserting an additional lens over the top of the one you have currently.

This approach, known as a "piggyback lens," likely can improve vision and may be considered safer than removing and replacing the existing lens.

If you require extremely high degrees of vision correction, such as for severe molder with an ophthalmologistyopia or astigmatism, your eye surgeon might advise combining the strengths of two intraocular lenses in one eye by using the "piggyback" approach.

IOL Cost and Availability

Since the IOLs mentioned in this article are all relatively new, not all cataract surgeons are trained to implant them. So if you would like to find out whether you're a candidate for one of these lenses, you may need to call several surgeons in your area to find out who uses them. Ask a lot of questions. You want to be sure that the surgeon you choose has a lot of experience with the lenses and is prepared to deal with any problems that could arise with your particular vision situation and eye health status.

Statistically, cataract removal/IOL implantation has one of the highest success rates among all surgeries, but it's important to know the risks beforehand. Ask your surgeon to explain any potential problems that your new IOLs could cause.

For example, some IOLs have been associated with a higher rate of posterior capsule opacification - that is, development of a membrane that is purposely left in the eye at the time of the cataract removal, which would require opening later with a YAG laser. Other issues include the incision sizes required for various IOLs, as well as the method of insertion.

You'll also need to think about cost. Cataract surgery is covered by Medicaid, Medicare and virtually all health insurance plans. The traditional IOL implants are fully covered as well, since insurers view these implants as medically necessary. But the newer implants - such as ReStor, ReZoom and Crystalens - are not currently covered (even if the procedure itself is), because they cost more and because their special features tend to be viewed by insurers as "nice to have" but not absolutely necessary. Medicare will reimburse the surgical facility for the cost of a traditional IOL, and the patient will be responsible for the difference, which could be anywhere from $1,500 to $2,500.

As more and more people choose the new IOLs, they may become fully covered by insurance some day. Check the terms of your health insurance to be sure.

When figuring cost, also take into account the eyeglasses or contact lenses that you would need if you opt for single-vision IOLs or if for some reason your multifocal IOLs don't satisfy your need for crisp vision at all distances.