It remains the best time in the history of the world to need cataract surgery. So much so, that thousands of people are paying to have their natural lens removed in a procedure called “Clear Lens Exchange” for one of the innovative lenses now available. Why would anyone do this? Many patients are having Clear Lens Exchange because it is a safer alternative to LASIK or PRK in certain patients and they want to the change to get rid of their glasses for good.
Each person has his or her own risks, so always talk to your eyeMD. Here is more information below.
As of 2016, there are now 4 different types of Intraocular Lens (IOL) Implants you can choose from.
1. Monofocal Lens: covered by all insurances; it only gives you clarity in 1 distance if you do not have astigmatsm
2. Extended Depth of Focus Intraocular Lens Implant: (EDOF-IOLs)
3. Multifocal IOLS
4. Accommodating lens
5. Toric Lenses
I have implanted all of the above and have thousands of happy patients. Still the decision on which one to choose can be overwhelming and confusing.
I hope this post helps clear up questions you may have.
A. The Innovative or Premium IOLs are not covered by insurance and include 2-4:
2. Extended Depth of Focus Intraocular Lens Implant: (EDOF-IOLs)
3. Multifocal IOLS: Multifocal lens implants are designed to produce a dual focus. Part of the lens is set for distance focus, and part of the lens is set for near, and this technology can significantly reduce your dependence on reading glasses. Multifocal diffractive optic lenses split light between distance, intermediate and near. The user can focus on only one distance at a time, leaving the blur from the other focal points to sometimes cause halo and glare. Patients who have had LASIK are not good candidates for a Multifocal IOL
4. Accommodating lens: The accommodating IOL needs either forward-backward axial movement or flexibility in lens shape or thickness to effect change in focal point from distance to near vision. Capsular fibrosis can impact the presbyopia-correcting capability and induce asymmetric vaulting, leading to lens tilt.
5. Toric Lenses: correct for astigmatism and 1 distance: so they are like a monofocal IOL but also correct astigmatism (an irregular cornea) better (it is more stable and more effective) than a “Limbal Relaxing Incision” (where the surgeon cuts the cornea to try to reshape the surface); this is an out of pocket expense as insurances do not cover them.
Conventional single-focus lens implants are called monofocal lenses because they optimize the
focus at a single location.
Multifocal lens implants are designed to produce a dual focus. Part of
the lens is set for distance focus, and part of the lens is set for near, and this technology can
significantly reduce your dependence on reading glasses.
Accommodating lens implants seek to
reduce eyeglass dependence according to a completely different principle. Accommodation is the
medical term which describes the natural ability of a young eye to focus by changing the lens
shape. If the lens implant could also change its shape or position, some focusing ability could be
restored.
Extended Depth of Focus Intraocular Lenses (EDOF- IOL) improves the range of vision without splitting light rays. The goal of the EDOF-IOL is to address patient expectations and demand for presbyopia correction without compromising functional vision across all distances. As opposed to the single focal point of monofocal lenses or two distinct foci for multifocal lenses, an EDOF-IOL smooths out the dips in the defocus curve by creating one elongated focal point. The only EDOF-IOL approved in the US is the TECNIS® Symfony IOL (Abbott Medical Optics, Inc.).
The Technis Symfony forms a step structure whose blaze angle elongates the focus of the eye to produce an extended range of vision. This enhanced design is combined with achromatic technology that corrects longitudinal chromatic aberrations. This results in sharper focus of light and increased contrast sensitivity. When combined with correction of spherical aberration, it increases retinal image quality without negatively affecting depth of focus. Studies conducted on the Symfony IOL showed sustained mean visual acuity of 20/20 or better at distance and intermediate, sustained through 1.5 D of defocus, and a 1.0 D increase in range of vision throughout the defocus curve.6 In one study, 97% of 31 subjects implanted with the Symfony IOL indicated that they would elect to have the lens implanted again.
The Crystalens implant is the first and only accommodating lens to be approved by the FDA. This
lens implant has an ingenious hinged design, to allow it to flex slightly. This enables your eye’s
natural focusing muscles to cause some flexing and movement of the lens, thereby adjusting the
focus. There is usually not enough lens movement to allow you to see far off in the distance one
moment and to read up close the next. As you would imagine, there is also individual variability in
the ability of the eye muscles to move the implanted lens. While the Crystalens does increase
one’s capacity to change focus relative to a standard single-focus lens implant, unfortunately it
does not duplicate the focusing ability that we all enjoyed when we were young.
The Crystalens should provide the ability to see without glasses across a greater range of different
viewing distances when compared to a Monofocal Implant or single-focus lens implant. For example, if an individual can
see well enough to drive with the Crystalens, they should also be able to focus in toward the
dashboard. The latter is a good example of our need to see many things at a mid-range or
“intermediate” distance – that is neither far off in the distance nor up close. Other examples of
tasks performed at an intermediate distance would include working on a desktop computer, playing
the piano, cooking, or viewing items on a shelf at arms length. For reading up close, patients with
the Crystalens typically wear low power reading glasses.
Unfortunately, neither the EDOF, Crystalens, nor multifocal lens implants are expected to eliminate the
need for eyeglasses 100% of the time. We do know that for close to 100% of patients with a monofocal lens, they will need glasses for at least 1 distance close to 100% of the time (there are exceptions if a patient requests monovision or if a patient never reads or does near work.)
There may always be situations where you are trying to see details at some
distance that are simply too small to be seen clearly. The print size and the amount of available light will make a difference. In addition, your retina must be completely healthy to achieve the
optimum results.
Because a single Multifocal lens or Crystalens implant may not provide enough focusing range to encompass both
the far and near distance extremes, one common strategy is to slightly stagger the separate
focusing range of each eye. For example, imagine that after the first eye surgery, you can see well
in the distance but cannot read without glasses up close. One option is to implant a Multifocal IOL or Crystalens in
your second eye that is focused closer in, rather than far away. Although this particular eye might
not see as well far away as the first eye does without glasses, the benefit is that it should see
better at near distances when you are not wearing glasses. Unless you were to test each eye
separately, this intended slight difference will generally go unnoticed, because the brain “blends”
what is seen by the two eyes together. The result would be an expanded ability to see across a
greater range of distances (from near to mid-range to far) than would be possible with either eye
alone. The results on doing this with an EDOF-IOL are still being studied but many patients who choose the Symfony do not need this “mini-monovision” or alteration.
This concept is similar to the “monovision” strategy that many contact lens wearers over the
age of 40 have used, except that it is accomplished without wearing contact lenses.
In a different situation, imagine that your first eye has good vision at the intermediate and near
ranges with an EDOF-IOL, Multifocal or the Crystalens, but is not very clear in the distance. Your second eye could then be
targeted for far distance to complement and supplement what you can already see with the first
eye. Again, improved distance focus would come at the cost of decreased near performance in that
one eye. Regardless of the strategy, your ability to see without glasses should improve after the
second eye receives a EDOF-IOL, Multifocal, Crystalens. Finally, in select circumstances, there is even an option to
combine a Crystalens in one eye, with a multifocal lens implant in the second eye. Mixing and matching eyes with Monofocal IOLS, EDOF-IOLS, Multifocals, and Crystalens or Trulign are still being researched fully. Many patients have done well with mixing and matching with Monofocals, Multifocals, Crystalenses but no one can be 100% sure you will be happy until the IOL is in your eye.
Remember that how often an individual requires glasses varies across a broad range of
percentages. At one extreme is always (people who must wear their glasses constantly = 100%); at
the other end of the continuum is never (some young individuals with perfect vision and a naturally
focusing lens never need glasses = 0%). Most of us are somewhere along this continuum in
between the two extremes. It is impossible to know in advance how often you will “need” glasses
after your Crystalens implants. This depends upon variables such as your retina, any remaining
astigmatism, and how visually demanding your everyday activities are. However, when compared
to a standard single-focus lens implant, the Crystalens should put you much closer to the desirable
end of the spectrum discussed above. This is because the Crystalens provides your eye with some
ability to adjust and vary the focus. Therefore, the Crystalens implants do offer the convenience of
being less dependent on glasses compared to standard single-focus lens implants.
There is always normal variability in the rate of visual improvement following uncomplicated
cataract surgery. Beyond the initial postoperative period, however, many Crystalens patients have
observed a gradual improvement in their ability to change focus over time. Since the Crystalens is
designed to be flexed and moved by the focusing muscles of the eye, it makes sense that in some
eyes, the strength of these focusing muscles improves with greater use.
Monofocals and EDOF-IOLS have the least percentage of complaints of halos and glare. The Crystalens and Trulign also have very low rates of halos and glare complaints. A head to head study comparing EDOF-IOL (ie the Symfony) compared to the Crystalens or Trulign have not been done yet.
Multifocal IOLS have the highest complaints of halos and glare. The design of the multifocal lens implant will always produce mild ghost images that appear as
rings or halos, particularly around lights at night. Although halos are much less apparent with the
newest generation of multifocal lens implants, and they always become less distracting over time, there is always some small risk that a given individual may struggle to adapt to them. In general,
the quality of vision at night is slightly less with a multifocal lens compared to a conventional singlefocus
lens implant. Because the Crystalens works according to an entirely different principle, it will
not produce the halos that are seen with multifocal lenses. The clarity and quality of vision at night
should be equally good as with a conventional lens implant.
Unfortunately it does not. Health insurance, including PPOs, HMOs, and Medicare, covers a
cataract operation with a standard lens implant when the cataract is bad enough to be considered
“medically necessary”. The additional fee to upgrade to a Symfony EDOF-IOL, a Multifocal, or Crystalens (accommodating lens implant) is required, because the added convenience of reducing your
dependence on eyeglasses is not “medically necessary.” This premium out-ofpocket
fee is usually required by the surgical center or surgeon’s office in advance. Rarely, unexpected situations might arise during surgery where I determine
that a Symfony, Multifocal, or Crystalens/Trulign might not be as stable in your particular eye due to the condition of the lens
capsule: sometimes, especially in a patient who has had previous eye trauma, eye surgery, eye inflammation, the capsule can become unstable or break open. I would implant a standard lens implant in this situation as it would be safer for your eye.
Many people are interested in surgical methods to reduce their dependence upon eyeglasses and
contact lenses. Laser eye surgery, such as LASIK, is the most common way to correct
nearsightedness if one is under the age of 40. However, for patients over the age of 50, laser
surgery by itself is less advantageous. By this time of life, any method that corrects your distance
vision (including contact lenses, LASIK, or a standard lens implant) will not work for reading up
close without glasses. Another problem with laser eye surgery, such as LASIK, is that it
complicates any lens implant surgery that is done later on for a cataract. Unfortunately,
determination of the correct lens implant power is very unpredictable in eyes that have had prior
LASIK.
The Crystalens implant is a technology that can allow a 50+ year-old eye to have some focusing
ability without glasses. For this reason, people over the age of 50 wearing strong prescription
glasses but with no other eye problems may elect to have accommodating lens implants in order to
see much better without glasses. Health insurance covers none of the costs, however, if there is no
cataract present. Because the natural lens must still be removed before implanting the Crystalens,
the procedure is performed in the same way as for cataract surgery. Thus, patients electing to have
lens implant surgery to reduce their need for glasses will never have to worry about developing
cataracts later on in life.
Like contact lenses or eyeglasses, every artificial lens implant model (standard, EDOF-IOL, multifocal, or
Crystalens) is manufactured in more than 60 different “powers”. As with prescription eyeglasses or
contact lenses, it is important to match the appropriate artificial lens implant power to your eye. To
prescribe the correct spectacle or contact lens power, we utilize trial and error to preview different
lens powers placed in front of your eye. When you are asked, “which is better, one or two?” you are
selecting the lens power that you see best with. However, because the artificial lens implant is
inserted inside the eye, and only after your natural lens (cataract) has been removed, it is
impossible for you to preview or “try out” different powers before surgery. Furthermore, once it is implanted, we cannot easily exchange the lens implant the way we could with contact lenses or
eyeglasses.
Fortunately, an appropriate lens implant power can be estimated using mathematical formulas that
utilize preoperative measurements of your eye’s dimensions. Although the measurements are very
accurate, there are individual variables that prevent this process from being 100% perfect. One
variable is the final precise position where the implant will end up inside your eye. Another
individual variable that may reduce your ability to see without glasses is astigmatism, which is a
naturally occurring imperfection in the optical shape of your cornea. Astigmatism is therefore not
corrected by the lens implant placed inside the eye. The overall process is accurate enough so that
most patients will see quite well without glasses in the distance. However, it usually won’t be
“perfect” and you might choose to wear mild prescription glasses for those occasional tasks that
require more precise distance focus.
For a Crystalens implant to work well, it is very important for the selected lens power to match your
individual eye. Despite flawless surgery, some patients with Crystalens implants are still not able to
see as well without glasses as they would like. What can be done if this is because the lens power
is “off”? One option is to wear glasses or contact lenses. A theoretical solution might be to
exchange the Crystalens implant for another with a different power. However, because of the risks
involved with removing a lens implant, it is usually safer to “enhance” or fine-tune any residual
prescription with an external LASIK procedure on the cornea instead. LASIK can also correct any
remaining astigmatism coming from your cornea.
All eye operations intending to reduce a person’s need for eyeglasses may need to be “enhanced”
with a second procedure. For example, nearsighted people choosing to have laser eye surgery
(e.g. LASIK) may need a second treatment if the first one does not fully correct their prescription.
This unpredictability is understandable because we are working with human tissue and not plastic
or metal. Likewise, it is possible that either the standard or Crystalens implant that has been
selected may not adequately focus your distance vision without glasses. Depending upon how far
off we are, laser enhancement may be a good option. The odds that this would need to be done
with a Crystalens are usually less than 5-10%, but the chances are greater in patients with a lot of
astigmatism or who are wearing very strong prescription glasses to begin with. The need will also
depend upon how much better one wants to see without glasses. You should know about this
possibility in advance before making your decision to have a Crystalens implant.
Like cosmetic surgery, taking extra steps to reduce spectacle dependence is a discretionary and
personal decision. Because this does not involve health advice or medical needs, the ultimate
decision is yours. Start by evaluating how strong your desire is to see as much as possible without
glasses. Every individual will value such convenience quite differently. My role, as your eye
surgeon, is to explain your options to you. To implant these special lenses, eye surgeons must be
trained and certified by the manufacturers. I have extensive experience with all types of lens
implants, and frequently lecture or write articles on this subject. Many lens manufacturers have
asked me to consult or to assist in training other eye surgeons. Fortunately, your options are not
limited by any lack of experience on my part.
If you are a patient with cataracts, you are considering surgery because your cataracts prevent you
from seeing well with your corrective eyeglasses. After cataract surgery you should be able to see
well for far, mid-range, and near distances with your new eyeglasses (assuming no other eye
health problems). The decision about which type of artificial lens implant to have will only affect
your ability to see without eyeglasses following cataract surgery. Compared to a standard lens
implant, the Crystalens should provide the added convenience of being able to adjust your focus
across a larger range of different distances without eyeglasses.
No current technology can eliminate eyeglasses, and how well you will perform with Crystalens
implants can vary because of individual factors. Nevertheless, they are an excellent option for
patients who already need cataract surgery and who want to decrease their reliance upon
eyeglasses. While Crystalens implants carry no guarantees, they should greatly improve the odds
that you will be able to see better overall without eyeglasses.
(Sandra Lora Cremers, MD, FACS heavily modified this from an original authored by Dr. David Chang.)