HOW DO MULTIFOCAL INTRAOCULAR LENSES WORK?
Intraocular lenses are medical devices that are implanted inside the eye to replace the eye’s natural lens. This is usually done during cataract removal surgery, or for a type of vision correction surgery called refractive lens surgery.
Standard “single focus” (monofocal) intraocular lenses will usually provide you with good focus at only one specific distance (far away) after the operation, and you would then wear spectacles to see objects closer to you.
Multifocal intraocular lenses have advanced technology to give you more independence from spectacles after the operation.
The multifocal intraocular lens technology can allow you to have focus both far and near without spectacles. It provides you with focus at more than one distance (“multifocal” means more than one single focal point).
ARE MULTIFOCAL INTRAOCULAR LENSES SUITABLE FOR ME?
Your surgeon will be able to do an assessment to establish whether multifocal lenses are suitable for you, or whether you can only have single focus lenses. Ultimately the decision is yours – consider the options that have been presented to you by your surgeon. Start by thinking about how important it is to you to live your life as much
as possible without using spectacles. All of us will value such convenience quite differently.
WILL THE MULTIFOCAL TECHNOLOGY TOTALLY ELIMINATE MY NEED FOR SPECTACLES?
For many, but not all patients, multifocal intraocular lenses will eliminate the frequent need for spectacles. There may however be situations where the print or the images are simply too small, or too far away to see without the help of spectacles. Other factors, like the print quality, size and amount of light will also have an effect on what
you can see.
How often you will need spectacles is dependent on a lot of things, including whether the “error” of your eyes can be fully corrected by the intraocular lenses, and how visually demanding your everyday activities are. However, when compared to the standard “single focus” intraocular lenses, you would require spectacles much less often with multifocal intraocular lenses.
People with good natural distance vision often go without spectacles, but when they need to see something up close (even for just a moment to look at a phone, photo, note or menu), they often have to put on their reading spectacles. To put reading spectacles on and take them off all the time, may inconvenience many people, so they might start
wearing them around their neck, leave many pairs lying around, or wear bifocal or multifocal spectacles permanently.
Most people with multifocal intraocular lenses enjoy the convenience of performing simple near tasks without putting on reading spectacles, and only wear them for prolonged reading.
WHY MUST MY BRAIN ADAPT TO MULTIFOCAL INTRAOCULAR LENSES?
With bifocal or multifocal spectacles, you look through the top part of the lens for distance vision, and through the bottom area of the lens for near vision. The multifocal intraocular lens is entirely different! The precisely engineered optic provides both a distance focus, and a near focus, AT ALL TIMES. Your brain must learn to automatically select the focus that is appropriate for the task at hand. There will be a learning process for your brain, called neuroadaptation, to use this technology optimally.
This works on the same principle as when you have the television on in the background, while you are having a conversation with someone. Your brain might “tune out” and “tune in” when you listen to one or the other. The same will happen with using the near and far focus of the multifocal intraocular lens.
It is also the same process that allows us to ignore background noise, such as traffic sounds or an air conditioning fan. How quickly this adaptation happens is different for everyone, but usually there is continuous improvement throughout the course of the first 12 months.
WHAT ARE HALOS?
With your new multifocal intraocular lenses, you may see halos at night, which looks like thin circles within or around a light source. This happens because light goes through both the near and far focusing zones of the lens. They do not obscure the vision, but rather can create a distracting ghost image. Even a standard intraocular lens can produce some halos at night, but they are more evident with a multifocal lens. Luckily these halos become less noticeable over time as your brain adapts and learns to selectively ignore them, through the process of neuroadaptation.
CAN THE MULTIFOCAL INTRAOCULAR LENS BE REMOVED IF I DON’T LIKE IT?
Yes, it is always an option, but there are risks associated with another surgery.
WILL I REQUIRE ANY OTHER PROCEDURES AFTER MY LENSES HAVE BEEN IMPLANTED?
The intraocular lens that is implanted into your eye, must be a specific “power” based on measurements of your eye before the operation. The correct power is calculated by mathematical formulas, and the entire process is quite accurate. There are however individual factors that prevent this process from being 100% perfect. One factor that
can influence your vision, is the final precise position where the intraocular lens will end up inside your eye after healing.
Even if everything goes well with the operation, it might be that you do not see as well without spectacles as you would like. There are then still options available to you. One option is to wear spectacles for certain tasks, another option is to enhance your vision with a corneal laser procedure. The odds are usually lower than 5% with multifocal intraocular lenses, but greater in patients with very bad eyes.