By David F. Chang MD and Brian S. Lee, MD, JD
If you have cataracts, you are considering surgery because your cataracts prevent you from seeing well even with corrective eyeglasses. After 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), multifocal (multiple focal points), and extended focus. This handout will help you to understand the differences.
Our eye is like a camera and must continually shift its focus from far to near and to various distances in-between. There are 4 primary distances at which we need to be able to see details:
Zone 1: Far distance (street signs, golf ball, distant animals, theater stage)
Zone 2: Indoor distances (across the room, faces across the table, TV 8 feet away)
Zone 3: Arm’s length (dashboard, store shelves, stove, desktop computer, bathroom mirror)
Zone 4: Reading distance (magazine, cell phone, tablet device, medicine bottle label)
Young people have the best system—a flexible human lens that is constantly and automatically adjusting its shape to change focus. This is like having an “autofocus” 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 by switching between different pairs of eyeglasses for each distance that we need to see. Bifocals and trifocals are like having 2-3 different pairs of glasses combined into one frame. Progressive (“no line”) eyeglasses allow us to see all four zones by looking through different parts of our eyeglasses as though we had 4 different pairs of glasses stacked one above the other.
With the single focus (monofocal) artificial lens implant, you select which one of the 4 zones you’d want to see optimally without any eyeglasses on. You then have the same eyeglass options to allow you to change your focus “manually” (i.e., moving the focus farther away or closer up). This could mean separate glasses for each distance, bifocals, trifocals, or progressive glasses. You can also continue to wear contact lenses.
How do these different lens implants differ?
The basic single-focus lens implant is called a monofocal lens because it optimizes the focus for a single zone. “Multifocal” means more than 1 focus and can potentially cover all 4 zones, allowing most patients to significantly reduce their dependence on reading glasses. Extended focus lens implants are an option that fits in between the other two. They employ a completely different mechanism (increasing depth of focus) to reduce dependence on eyeglasses. We usually refer to this lens by its brand name, Vivity. By covering 3 out of the 4 zones, the Vivity lens is designed to provide continuous focus over a greater range of distances than the monofocal lens. For example, it is a good option for patients that want good natural focus without eyeglasses at outdoor and indoor distances and mid-range (zones 1, 2, & 3). Compared to the basic monofocal lens implant set for far distance (zone 1), patients with the Vivity 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 use reading glasses for many near tasks, and certainly for small print (zone 4). It is also possible to target zones 2, 3, & 4 with Vivity in the second eye. This strategy to create a slight difference is generally well tolerated and improves the near vision without eyeglasses. Unlike with traditional “monovision,” both eyes still work together as a team. Multifocal lens implants, such as the PanOptix, are able to cover all 4 zones in one lens, but the tradeoff is that they create more rings around lights at night. Like single focus lens implants, Vivity does NOT produce these additional rings and halos at night.
How does the Vivity lens create an extended range of focus?
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. Vivity uses sophisticated optics to create more depth of focus compared to a single focus lens implant. Unlike with progressive bifocal or trifocal spectacles, there is no need to look through different parts of the lens implant to see at different distances. Instead, Vivity creates a natural extended range of vision.
What if I have astigmatism?
Astigmatism is a natural blur or misfocus caused by an imperfect shape of the cornea at the front of the eye. Like nearsightedness, astigmatism isn’t a disease, but rather a misfocus that requires corrective eyeglasses for the clearest vision. Instead of placing the astigmatism correction into one’s spectacles, it can be incorporated into the artificial lens implant instead. The name of this popular feature is toric, and it can be built into any of the 3 lens implant types (monofocal, extended focus, or multifocal). A Vivity lens with astigmatism correction is called a toric Vivity.
Will this more expensive technology eliminate the need for glasses?
Vivity lens implants usually won’t completely eliminate the need for eyeglasses. Without any 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 distance focused monofocal lens implants, there should be much less of a need to put on and take off reading glasses. It is possible that 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 driving at night or unfamiliar areas even if daytime driving is fine without glasses. Because the Vivity lens covers 3 out of the 4 important zones, patients with this lens usually don’t need to wear trifocals or progressive glasses. They simply use reading glasses.
Does the Vivity 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. Patients with a Vivity lens typically gain good natural outdoor and indoor vision in their operated eye by a week following surgery.
Does insurance cover the premium cost to upgrade to a Vivity implant?
Unfortunately, it does not. Health insurers, including PPOs, HMOs, and Medicare, cover a cataract operation with a basic monofocal lens implant when the cataract is bad enough for surgery to be considered “medically necessary.” Patients may elect to have the more expensive Vivity extended focus 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 Vivity lens implant might not be as stable in your particular eye due to the condition of the lens capsule. We would implant a basic single focus lens implant in this situation, and the premium fee will be refunded.
Can patients without cataracts have the Vivity?
People 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 or contact lenses. Health insurance covers none of the cost, however, if there is no cataract present. Because the natural lens must still be removed before implanting the Vivity, 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 Vivity implant?
Like contact lenses or prescription eyeglasses, every artificial lens implant model (monofocal, multifocal, or Vivity) is manufactured in more than 50 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 eyeglasses or contact lenses, we utilize trial and error to preview different lens powers placed in front of your eye. When you are asked, “which is better, 1 or 2?” 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, we must estimate some individual variables that prevent this process from being 100% perfect. One variable is the final precise position where the implant will rest 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 Vivity 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 thin 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 individual’s unique healing process. What can be done if this is because the lens power formulas are “off”? One option is to wear glasses or contact lenses as needed. A theoretical solution might be to exchange the Vivity implant for another with a different power. However, it may be more precise instead to “enhance” or fine-tune any residual prescription with an external laser procedure on the cornea, such as LASIK or PRK. Laser can also correct any remaining astigmatism coming from your cornea. The odds that this would need to be done with a Vivity are usually less than 3%, 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 Vivity lens implant.
What do you recommend I do?
Whether to invest the extra costs to reduce your need for eyeglasses 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 guarantee that you’ll never need eyeglasses, and how well you perform with Vivity lens implants can vary because of individual factors. Nevertheless, they are an excellent option for patients who want to decrease their reliance upon eyeglasses as much as possible. 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. The lens will never wear out, and unlike expensive hearing aids, they cannot fall out and get lost!