Intraocular Lenses (IOLs): Including Premium, Toric and Aspheric Designs
Artificial intraocular lenses, or IOLs, 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 an artificial one.
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. multi-piece, 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, consider your choices in the following summary of the most recently developed IOLs.
Premium IOLs: Multifocal & Accommodating
Traditional IOLs are monofocal, meaning they offer vision at one distance only (far, intermediate or near). They definitely are 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 at arm's length.
The new multifocal and accommodating IOLs such as Crystalens and Trulign offer the possibility of seeing well at more than one distance, without glasses or contacts. Examples of multifocal IOLs are different versions of Alcon's AcrySof IQ ReSTOR. Abbott Medical Optics also offers the Tecnis and ReZoom multifocal lenses.
Presbyopia-correcting IOLs are considered "premium" lenses, which means that you must pay any associated extra cataract surgery costs yourself. Medicare and most health care plans will not cover these extra costs, because the additional benefits of these IOLs are considered a luxury and not a medical necessity.
Toric IOLs for Astigmatism
Toric IOLs designed to correct astigmatism also are considered "premium" lenses, and like multifocal and accommodating IOLs likely will cost you extra because of benefits that are unavailable in conventional IOLs.
The aspheric version of Alcon's AcrySof IQ Toric IOL is an astigmatism-correcting "premium" intraocular lens.
FDA-approved in 1998, the Staar Surgical Intraocular Lens was the first toric IOL available in the United States. The Staar toric IOL comes in a full range of distance vision powers, in two versions. One corrects up to 2.00 diopters (D) of astigmatism and the other corrects up to 3.50 D.
The FDA also approved the AcrySof IQ Toric IOL (Alcon) in September 2005. Different models of this toric IOL can correct 1.50 to 3.00 D of astigmatism. This lens also is available in aspheric versions for crisper vision. Different models also can filter potentially damaging UV or blue light.
In May 2013, the FDA approved the Trulign Toric IOL (Bausch + Lomb), the first accommodating IOL that also corrects astigmatism. The lens, which can correct corneal astigmatism between 0.83 D and 2.50 D, offers patients clear distance, intermediate and near vision without glasses after cataract surgery.
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 inside the eye. 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.
Monovision With Intraocular Lenses
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 meaning, your eyes aren't working together as they once did.
People who do best with this method already are accustomed 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.
Mixing multifocal lenses is another method of achieving a type of modified or "blended" monovision by using one type of IOL that emphasizes distance vision and another that emphasizes intermediate vision.
Traditional IOLs are spherical, meaning the front surface is uniformly 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 original Bausch + Lomb offering is called the SofPort Advanced Optics IOL.
Bausch + Lomb also recently introduced the Akreos AO Aspheric IOL, and promotes this lens as having the ability to reduce visual aberrations. The Tecnis Z9000 (Abbott Medical Optics) also is advertised with this feature, which can improve ability to see in varying light conditions such as rain, snow, fog, twilight and nighttime darkness.
According to manufacturer AMO, 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.
The Softec HD (Lenstec Inc.) is an aspheric intraocular lens (IOL) that may help reduce visual aberrations. The IOL received FDA approval in April 2010.
Aspheric IOLs also are available from Alcon, including the AcrySof SN60WF that includes the blue light-blocking feature discussed below and the aspheric version of AcrySof IQ ReSTOR.
Many aspheric IOLs have a Medicare "new technology" designation, which enables extra reimbursement to the surgeon of $50 per lens.
Some cataract surgeons have debated the benefits of aspheric IOLs, because the contrast sensitivity benefit may not 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 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.
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 to 500 nanometers (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 restore 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.
However, some studies including one based in Austria indicate that some contrast sensitivity might be lost with a blue light-filtering IOL. In the Austrian study, few people who had blue light-filtering IOLs noticed any decrease in vision quality when they were given a questionnaire although subtle differences were noted in eye tests.
A study reported in the December 2010 issue of Journal of Cataract & Refractive Surgery found that cataract patients with yellow-tinted IOLs had more difficulty seeing in the blue ranges of color under dim lighting conditions.
Light-Adjustable Lenses (LALs)
Already available in some countries outside the U.S., light-adjustable lenses (LALs) can be altered for better vision correction even after they have been surgically implanted. Adjustments are made through a light delivery device developed by Calhoun Vision of Pasadena, Calif.
LALs tested in a recent small Tijuana study involving 14 eyes were treated with a certain wavelength of light to alter the curvature of the lens after surgical implantation. This helped eye surgeons achieve targeted corrections within a quarter diopter in all but one of the eyes.
Light-adjustable intraocular lenses are now undergoing FDA clinical trials, and may become commercially available in the U.S. if they are proven safe and effective.
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 myopia 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
Because some of the IOLs mentioned in this article are 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 cataract surgeon you choose has plenty 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, clouding of a membrane that is purposely left in the eye at the time of the cataract removal which would require treatment 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 costs of traditional IOL implants are fully covered as well, since insurers view these implants as medically necessary.
But costs associated with the newer implants such as ReSTOR, ReZoom and Crystalens are not fully covered (even if the procedure itself is), because these premium IOLs are more expensive and 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 per eye, depending on the surgeon and the IOL.
As more and more people choose the new IOLs, they may become fully covered by health insurance or vision insurance some day. Check the terms of your insurance policy to be sure of the coverage you have prior to surgery.
When figuring cost, also take into account the eyeglasses or contact lenses that you will 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.
Have questions? Try reading Q&As answered by cataract surgeon Charles Slonim, MD.
[Page updated May 2013]