Multifocal lens implants are designed to reduce your dependence on eyeglasses. However, if you had a conventional ‘single focus” lens implant, the better you can see in distance without glasses the blurrier it will be up close. You would then need to wear reading glasses in order to see clearly at near.
What are the goals after cataract surgery with Multifocal Implants?
Our goal is for you to function without glasses 90% of the time. This means that with both eye open, you should be able to legally drive without glasses and should be able to read a magazine article with good lighting and without glasses.
HOW DOES THE MULTIFOCAL WORK?
With bifocal eyeglasses, you look through the top part of the lens for distance and the bottom part for near. The multifocal lens implant is entirely different. It provides both a distance focus and a near focus at the same time. Your brain will learn to automatically select the focus for the task at hand. This is like having background music playing in the room during a conversation. Your brain might “tune out” one to listen to the other. It takes time to learn using this focus system. For example, you will need to find the best distance to hold reading material – the “sweet spot”. For this reason many patients say that their vision continues to improve gradually in the first several months after surgery.
WILL MULTIFOCAL LENS IMPLANTS ELIMINATE THE NEED FOR GLASSES?
Unfortunately, multifocal lens implants usually do not eliminate eyeglasses entirely. There will be some times where the print or image is simply too small or too far away to be seen clearly without glasses. The print quality and the amount of available light will make also a difference. In addition, your eyes must be completely healthy to achieve optimal results.
How often an individual requires glasses varies. At one extreme is always (people who must wear their glasses constantly =100%); at the other extreme is never (some young individuals with perfect vision and a naturally focusing lens never need glasses = 0%). Most of us are somewhere in the middle. It is impossible to know in advance how often you will “need” glasses with your multifocal lens implant. This depends on your retina, any remaining astigmatism, and how visually demanding you activities are. However, when compared to the single-focus (conventional) lens implants, the multifocal should decrease your need for eyeglasses. This is because the multifocal lens implant provides you with focus at more than one distance (“multifocal” means more than one optimal focal points): far, intermediate, and near.
Regular lens implants work well at providing distance vision. People, who naturally see well in the distance, often go without eyeglasses outdoors or around the house. However, when they need to see something up close – even for just a moment – they might have to put on reading glasses. Examples of common momentary near tasks include looking at cell phone, a photo, a menu, a boarding pass, an envelope address, a handwritten note, a price tag or a receipt. Having to take their reading glasses on and off frequently is inconvenient to many people. Because of this, they might wear their reading glasses around their neck, scatter multiple pairs around the house or simply wear bifocals all the time. Although they might still prefer eyeglasses for prolonged reading, most people with multifocal lens implants enjoy the convenience of performing these simple near tasks without having to put on reading glasses.
WILL I SEE HALOS?
Depending on the size of your pupils you might see halos, which appear as rings around lights at night. These halos are different from those typically caused by cataracts and are less problematic. Viewing distant lights through both the near and far focusing zones of the multifocal lens implant could lead to halos. They do not obscure the vision, but can create distracting ghost images.
Fortunately, these halos become less noticeable and distracting over time as the brain learns to ignore them. This is the same process that allows us to ignore background noise such as traffic sounds or and the humming noise from an air conditioning fan. As these sensations become more familiar over time, we often become less aware of them. How quickly this occurs varies from individual to individual. However, experience has shown that this is a gradual process, and the nighttime ghost images continue to diminish over several months after surgery.
Even a conventional lens implant can produce halos at night, but they are more evident with a multifocal lens implant. Halos are often quite noticeable during the first 24 hours after surgery when your pupil is dilated. Do not be alarmed or misled by this temporary situation.
CAN A MULTIFOCAL LENS BE IMPLANTED IN JUST ONE EYE?
Yes, this is possible when the other eye already has a conventional implant, or when there is no cataract in the opposite eye. However, the ability to see both far and near without glasses is better when you have a multifocal lens in both eyes. With a multifocal lens implant in one eye, the brain simply blends together the vision from both eyes. Some individuals might take longer than others to adapt to this situation. For this reason, you should not consistently compare one eye to the other. With a multifocal lens in one eye, you should still be able to see things close up. However, if you had received a conventional single-focus lens implant, you would need to wear glasses for near.
CAN THE MULTIFOCAL LENS BE REMOVED IF I DON’T LIKE IT?
This is always possible but entails the risks of additional surgery. However, there might be a rare individual for whom the halos continue to be unacceptable. You may then elect to have the multifocal replaced with a conventional lens implant. One should not rush into this decision because the ghost images nearly always improve over time.
DOES INSURANCE OVER THE EXTRA COSTS OF A MULTIFOCAL?
Unfortunately it does not. Health insurance, including PPO’s, HMO’s, and Medicare, covers a cataract operation with a conventional lens implant when the cataract is bad enough to be considered ‘medically necessary’. The additional fee to upgrade the lens implant to a multifocal implant is not covered, 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 situation might arise during surgery, during which if I determine that a multifocal lens implant might not be suitable for your particular eye, I would implant a conventional implant in this situation and your multifocal lens fee would be refunded.
CAN PATIENTS WITHOUT CATARACTS HAVE MULTIFOCAL LENS IMPLANTS?
The multifocal lens implant allows a 50-or-older eye to have focus both far and near 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 multifocal 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 a multifocal lens, the procedure is performed in the same manner as in cataract surgery. Patients electing to have lens implant surgery to reduce their need for glasses will never develop cataracts.
WHO MIGHT NEED LASIK AFTER A MULTIFOCAL LENS IMPLANT?
Like contact lenses or eyeglasses, every artificial lens implant model is manufactured in more than 60 different “powers”, similar to the numbers that you see on your eyeglass prescription. 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 eyes. 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 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 glasses.
Fortunately, an appropriate lens implant power can be estimated with mathematical formulas that use the preoperative measurements of your eye. Although these measurements are very accurate, there are individual variables that prevent this process from being 100% perfect.
Another problem is astigmatism, which is a naturally occurring imperfection in the optical shape of your cornea. Astigmatism is not corrected by the multifocal lens implant place inside the eye and is another reason that might reduce your ability to see without glasses. Overall, the process is accurate enough so that most patients will see well without glasses in the distance (assuming that was the target). However, it might still not be “perfect”, and you may choose to wear mild prescription glasses for those occasional tasks that require more precise distance focus.
For a multifocal lens implant to work well, it is very important for the selected lens power to match your individual eye. Despite flawless surgery, some patients with multifocal lens implants still cannot see as well as without glasses as they would like. What can be done if the vision is ‘off’? One option is to wear glasses or contact lenses. Another solution is to exchange the multifocal lens implant for another with a different power. Because of the inherent risks involved with removing a lens implant, it might be best fine-tune any residual prescription with a LASIK procedure on the cornea instead. LASIK can also correct any remaining astigmatism from your cornea.
All eye operations intended to reduce a person’s need for eyeglasses might need to be ‘enhanced’ with a second procedure. For example, nearsighted people choosing to have laser eye surgery (e.g., LASIK) might need a second treatment if the first one does not fully correct their prescription. This unpredictability is understandable because we are working with human tissues, not plastic or metal. Likewise, it is possible that the conventional or multifocal lens implant that has been selected may not adequately focus your distance vision without glasses. Depending on how far off we are, laser enhancement might be a good option. The odds this would need to be done with a multifocal implant are usually less that 5% to 10%, but these odds are greater in patients with significant astigmatism or strong prescriptions. The need for LASIK will also depend on how much better one wants to see without glasses. Because there would be an additional cost and procedure involved, you should know this possibility in advance before making your decision to have a multifocal lens implant.
WHAT DO YOU RECOMMEND I DO?
Like cosmetic surgery, taking extra steps to reduce dependence on eyeglasses is a discretionary, personal decision. Because having a multifocal lens implant is not medically necessary, the ultimate decision is yours. Start by evaluating how strongly you 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.
If you are a patient with cataracts and are considering surgery because your cataracts prevent you from seeing well with your correction glasses, both conventional and multifocal implants are good options. With conventional implant, after cataract surgery you should be able to see well for both far and near distances with your new eyeglasses (assuming no other eye health problems). However, multifocal lens implants will provide the added convenience of being able to see far and read many things up close without glasses. The decision about which type of artificial lens implants to have will only affect your ability to see without eyeglasses following cataract surgery.
No current technology can eliminate eyeglasses, and how well you will perform with multifocal lens implants can vary due to individual factors. Nevertheless, multifocal lens implants is an excellent option for patients who already need cataract surgery and who want to decrease their reliance on eyeglasses. While multifocal implants carry no guarantees, they should greatly improve the odds that you will be able to read and see better overall without eyeglasses.