We all want to be young again, at least when it comes to vision: visual quality, range of vision, and freedom from glasses is best when we are in our 20s (or even younger). With age comes presbyopia and then cataracts — and while our current range of IOLs is excellent, nothing beats being young again.
When we speak of extended depth of field (EDOF) IOLs, it is helpful to review the difference between depth of field and depth of focus. Though ophthalmologists use these terms interchangeably, there is a difference between the two:
The patients desire the widest depth of field so that they can see everything from far away to up close, all without glasses. In terms of optics, we are looking at the depth of focus within the eye. Either way, our goal is a wider depth of field and a wider depth of focus, so that our patients can have greater freedom from glasses.
We do have IOLs which can restore much of the vision at the time of cataract surgery. The monofocal IOLs give the best visual quality but also have the narrowest range of focus. The trifocal IOLs (like the Alcon PanOptix) give the widest range of vision without glasses but they compromise image quality with reduced contrast and nighttime glare/halos/rings. There are extended depth of focus (EDOF) IOLs which aim to mitigate that situation by elongating the depth of focus. The commonly used designs are the small aperture IOLs (Acufocus), the diffractive EDOF (Tecnis Symfony), and now the wavefront beam-shaping EDOF (Alcon Vivity).
The Alcon Vivity uses a central optical zone that is beam-shaping: it changes the wavefront of these central light beams to elongate the depth of focus. This gives a wider range of good vision without glasses, with patients seeing at least 1 line better for intermediate and near when compare to a monofocal IOL.
If we want to give our patients the widest range of vision without glasses, then using a trifocal IOL like the Alcon PanOptix would be the best choice. However this IOL will give less contrast as well as nighttime glare/halos/rings. The monofocal IOL will give the best image quality but also the most limited range of vision without glasses. The Alcon Vivity EDOF IOL splits the difference, giving about 50% more visual range than the monofocal while avoiding the nighttime glare/halo/rings of the diffractive PanOptix.
The increased depth of focus is seen clearly in the MTF and Defocus curves above. The MTF is modulation transfer function and it shows that while there is an increased depth of focus with the Alcon Vivity IOL, it comes with a decrease in the MTF at the 0.00 (plano) focal point which we see as a decrease in the contrast.
We are now ramping up the use of the Alcon Vivity IOL in our practice and we anticipate that it will complement the other IOL options that are available to our patients. Our goal is to individualize the treatment and the surgery to each individual patient and each specific eye. We always welcome additional tools in the toolbox and this IOL will play a role in the spectrum of options for our patients.
Click below to learn more about EFOD IOLs and how they can be used to help your patients:
