Cataract surgery is not what it once was. In its earliest form, the removal of cataracts was through a technique known as couching, which involved using a sharp instrument to simply poke the cataractous lens out of the way. Though there was no longer a cloudy lens in the way of light entering the eye, there was, in fact, no lens there at all. This approach to cataracts (unsurprisingly) did not provide optimal post-op vision and was associated with several complications.
Fortunately, modern medicine has moved far ahead of those dark times. In fact, we’ve advanced so far that patients contemplating cataract surgery often have more than one option of intraocular lens (IOL) implant. Decisions, decisions!
What is an Intraocular Lens?
An IOL is an artificial lens implant made from an inert, biocompatible material such as silicone or acrylic. It is designed to mimic the eye’s natural crystalline lens (you know, that one that developed a cataract), but even better – an IOL can be calculated to be whatever power you want. That means if you were previously +7.00 hyperopic, wearing coke-bottle glasses, these coke bottles are now inside your eyes.
Your options for an IOL during cataract surgery include:
- Monofocal IOLs: these provide clear vision at a single distance, whether that’s for far vision or near vision.
- Toric IOLs: which correct for astigmatism, a type of refractive error. Similar to the monofocal IOL, a toric IOL is still designed to only correct for vision at one particular focal distance.
- Multifocal IOLs: now we get a little more complicated, with multifocal IOLs containing multiple zones within each lens that correct for different distances. This means you get both far, near, and sometimes also intermediate vision within the one eye.
- Extended depth of focus IOLs
How do Extended Depth of Focus (EDOF) IOLs Work?
Out of the previously mentioned types of IOLs, EDOF lenses are the newest to the block. The first one was approved by the FDA in just 2016.
Similar to multifocal IOLs, an EDOF lens offers a wider range of focusing distances compared to just the one found with a monofocal lens. However, where the multifocal IOL has separate zones of differing power to create that profile of multiple focal lengths, an EDOF IOL has only one focal length but this focal point is stretched out (or extended, as the name might suggest), providing continuous functional vision from distance to intermediate, and often with some near vision, too.
Advantages of EDOF IOLs
The optical design of an EDOF lens means you still achieve a range of clear vision not available with a monofocal IOL, but with a greatly reduced risk of the common issues that are often associated with a multifocal IOL, such as:
- Glare
- Haloes
- Poor contrast sensitivity
- Adaptation challenges
And compared to a monofocal IOL, people with an EDOF lens experience a greater freedom from their glasses as they have a wider range of functional vision. Where someone with a monofocal IOL correcting for far vision will still need to whip out reading glasses for computer work, someone with an EDOF lens can read their screen then glance up at their boss charging across the office (and read their boss’s expression, too), all without glasses. They can even see well enough to make a hasty strategic exit from the office until their boss has calmed down, again, all without glasses.
Disadvantages of EDOF IOLs
Though EDOF lenses are usually considered to have the benefits of multifocal IOLs without the bothersome visual disturbances, there is still the potential to experience haloes and glare, especially if the ambient lighting is low.
Other things to consider with EDOF lenses include:
- You may still need to wear spectacles for certain tasks, particularly as near vision (such as for reading a book or threading a needle) is not as crisp compared to your pre-cataract days or if you had opted for a multifocal IOL
- The higher cost; while Medicare covers monofocal IOLs, EDOFs are excluded from Medicare support and are also not always covered by private health insurance
Is an EDOF IOL Right for Me?
Deciding which IOL is best suited for your eyes and your lifestyle will be done in collaboration with your cataract surgeon. Together, you will consider factors such as:
- The overall health of your eyes, including your retina and cornea, and the state of your cataracts
- Your visual tasks and demands
- Your expectations of the surgery and your post-op vision
- Your lifestyle and how open you are to still wearing glasses on occasion after surgery
As with any medical procedure, cataract surgery (with or without premium EDOF IOLs) comes with risks. A comprehensive eye exam with your optometrist or ophthalmologist will help to guide your decision on the timing of surgery and which type of intraocular lens will be most appropriate.