By David F. Chang MD
If you have cataracts, you are considering surgery because your cataracts prevent you from seeing well even with corrective eyeglasses. After cataract surgery, you should be able to see well at far, mid-range, and near distances with new eyeglasses (assuming no other eye health problems). The decision about which type of artificial lens implant to have will affect your ability to see without eyeglasses following cataract surgery. There are 3 categories of artificial lenses for cataract patients to choose from: single focus (monofocal), bifocal (also called a multifocal because it has 2 separate focal points), and extended focus. This handout will help you to understand the differences.
Our eye is like a camera that must constantly shift its focus from far to near and various distances in-between.
There are four primary zones or distances that we need to be able to see:
- Far distance (road signs, distant animals, movie screens)
- Indoor distances (pictures on the wall, faces across the dinner table, TV 8 feet away)
- Arm’s length (dashboard, store shelves, stove, desktop computer, piano, bathroom mirror)
- Reading distance
The best system is what a young person has, a human lens that is constantly and automatically changing shape to adjust focus. This is like having an “auto-focus” camera where you just point the camera (or eye) at something and the focus is automatically and instantly adjusted. With age, we all lose this convenience and end up with a “manual” focus camera—we must manually change the focus. We do this either by switching between different pairs of eyeglasses for each distance that we need or by using bifocal, trifocal, or progressive (“no line bifocal”) eyeglasses. Progressive glasses allow us to see all four zones by looking through different parts of the spectacle lens as though we had 4 different pairs of glasses stacked one above the other.
With the standard single focus (monofocal) lens implant, you can select which of the 4 zones you’d want to see optimally without any eyeglasses on. You then have the same eyeglass options as everyone else over the age of 50 to allow you to “manually” change your focus (i.e., moving the focus farther away or closer up). This could mean separate distance, reading, and computer glasses, bifocals, trifocals, or progressive bifocals. You can also continue to wear contact lenses.
Two types of premium lens implant options—the bifocal and the extended focus lens — are designed to reduce your dependence on glasses compared to if you had received a single focus lens implant.
How do bifocal and extended focus lens implants differ?
Conventional single-focus lens implants are called monofocal lenses because they optimize the focus at a single location. Bifocal lens implants are designed to produce a dual focus (“multifocal” means more than 1 focus). Because part of the lens is set for distance focus (zone 1), and part of the lens is set for reading distance (zone 4), this technology can significantly reduce your dependence on reading glasses. Extended focus lens implants employ a completely different mechanism to reduce dependence on eyeglasses—extended depth-of-focus. Instead of creating one or two separate focal points, this lens is designed to provide continuous focus over a range of distances. We usually refer to this lens by its brand name, the Symfony, and it is appropriate for patients that want good natural focus without eyeglasses at outdoor and indoor distances and mid-range (zones 1, 2, and 3). Compared to a conventional monofocal lens implant set for far distance (zone 1), patients with the Symfony lens have noticeably better mid-range vision at arm’s length (zone 3). There may be some ability to read larger print without spectacles, but you should expect to still use reading glasses for many near tasks, and certainly for small print. Naturally, there is some individual variability in the range of focus that each patient enjoys, depending on factors such as your age and the health of your retina. Having the Symfony in both eyes and having good lighting will also improve one’s near vision without eyeglasses.
How does the Symfony create an extended range of focus?
Unlike with progressive bifocal spectacles, there is no need to look through different parts of the lens implant to see at different distances. A photographer can photograph your face and have the background very blurred to create a portrait-like effect. Alternatively, the photographer can alter the camera settings to have your face and the background simultaneously in clear focus. This latter camera setting has more “depth-of-focus” and would be used to take your photo in front of the Eiffel Tower to show that you were in Paris. The Symfony uses sophisticated optics to create more depth-of-focus compared to a standard single focus lens implant.
What if I have astigmatism?
If the shape of the cornea at the front of the eye is imperfect, this creates a natural blur or misfocus called astigmatism. The blur from astigmatism is corrected by spectacle lenses. Like nearsightedness, astigmatism isn’t a disease, but rather a natural misfocus that requires corrective eyeglasses for the clearest vision. Instead of placing the astigmatism correction into the patient’s spectacles, it can be incorporated into the lens implant instead. This feature can be incorporated into each of the 3 lens implant categories (monofocal, bifocal, or Symfony extended focus), and any lens containing astigmatism correction is called a toric lens.
Will I see halos?
The extended focus implant may produce faint starbursts around a headlight at night as your pupil dilates. Patients describe this as a radiating cobweb pattern that becomes less distracting over time. The majority of patients are not significantly bothered by this, but there is always some small risk that certain individuals may struggle to adapt to them. By design, these are less apparent than the halos and starbursts that are seen with a bifocal (multifocal) lens implant.
Will this more expensive technology eliminate the need for glasses?
Unfortunately, Symfony lens implants won’t completely eliminate the need for eyeglasses.
With no eyeglasses on, Zone 4 (reading) will be less blurry than with a monofocal lens implant, but you’ll need reading glasses for the newspaper. You may be able to read larger print, such as a menu or your cellphone, without reading glasses. Therefore, compared to having distant monofocal lens implants, there should be much less need to put on and take off reading glasses continually. There may also be situations where low power distance eyeglasses would boost your ability to see critical details in the far distance. For example, some patients have “glove compartment” eyeglasses for freeway driving at night, whereas daytime driving is fine without glasses.
Does the Symfony lens implant increase the risk or recovery time of my surgery?
Your cataract surgery is performed the same way regardless of the type of lens implant selected. Therefore, the surgical risks are not increased or altered by using one type of lens or another. Postoperative physical restrictions are no different either because all of these lens implants go through the smallest incisions. You should always expect your vision in the operated eye to be temporarily blurry during the first week after surgery regardless of the type of artificial lens implant used. Most patients wait approximately one month before getting new prescription eyeglasses following cataract surgery. Patients with the Symfony typically regain good natural outdoor and indoor vision in their operated eye by a week following surgery. They would typically see well up close with inexpensive, over-the-counter reading glasses until they are stable enough to get a prescription for any new eyeglasses that are needed.
Does insurance cover the premium cost to upgrade to a Symfony implant?
Unfortunately, it does not. Health insurance, including PPOs, HMOs, and Medicare, covers a cataract operation with a standard monofocal lens implant when the cataract is bad enough for surgery to be considered “medically necessary.” Patients may elect to have the more expensive Symfony extended focus implant or a bifocal lens implant by paying the cost difference out of pocket. The additional fees are not covered by any insurance because the added convenience of reducing your dependence on eyeglasses is not “medically necessary.” We ask that you pay this premium out-of-pocket fee in advance. Rarely, unexpected situations might arise during surgery where we determine that a Symfony or a bifocal lens implant might not be as stable in your particular eye due to the condition of the lens capsule. We would implant a standard single focus lens implant in this situation, and the extra premium fee will be refunded.
Can patients without cataracts have the Symfony?
People over the age of 50 wearing strong prescription glasses but with no other eye problems may elect to have extended focus 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 Symfony, the procedure is performed in the same way as 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.
Who might need a LASIK “enhancement” after a Symfony implant?
Like contact lenses or prescription eyeglasses, every artificial lens implant model (standard, bifocal, or Symfony) is manufactured in more than 60 different powers to meet the individual requirements of our entire population. As with prescription eyeglasses or contact lenses, your eye will only see well in the distance if the appropriate artificial lens implant power is selected. 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 in the distance. However, because the artificial lens implant is inserted inside the eye only after your natural lens (cataract) has been removed, it is impossible for you to “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. The overall process is accurate enough so that most patients will see well without glasses in the distance. For example, if perfect 20/20 distance vision is an “A”, you could end up with an “A” or you might end up with “B+” distance vision without glasses. With the latter, you could then choose to wear mild prescription glasses to get your distance vision to an “A” for those occasional tasks that require more precise or critical far distance focus, such as night driving.
Despite flawless surgery, some patients with lens implants are still not able to see as well in the distance without glasses as they would like. This unpredictability is understandable because we are dealing with a human organ and each person’s unique healing process. What can be done if this is because the lens power is “off”? One option is to wear glasses or contact lenses as needed. A theoretical solution might be to exchange the Symfony implant for another with a different power. However, it may be more precise to instead “enhance” or fine-tune any residual prescription with an external laser procedure on the cornea, such as LASIK or PRK. LASIK can also correct any remaining astigmatism coming from your cornea. The odds that this would need to be done with a Symfony are usually less than 5%, 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. However, because there would be an additional cost and procedure involved, you should know about this possibility in advance before making your decision to have a Symfony lens implant.
What do you recommend I do?
Whether to invest the extra costs to reduce your need for glasses or contacts is a personal decision that does not involve eye health or surgical safety. Start by evaluating how often you wear your eyeglasses, and how strong your desire is to see as well as possible without them. Different individuals may value such convenience quite differently. Our role, as your eye surgeon, is to explain your options to you. We have extensive experience with all types of lens implants and frequently lecture to other eye surgeons on this subject.
No current technology will totally eliminate eyeglasses, and how well you perform with Symfony 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. Although this is an expensive option, you will be looking through the lens implant you select during every waking minute for the rest of your life.