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BLOG: Simplifying refractive targeting
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In my last post, I talked about the evolution of my femtosecond laser-assisted cataract surgery settings. Today, I’d like to share how my approach to refractive targeting with presbyopia-correcting IOLs has evolved over time and with the introduction of new technology.
Phase 1: Mix and match
When low-add multifocal IOLs were first introduced, my approach was to implant the lowest-add ZKB00 lens (Johnson & Johnson Vision) in the patient’s dominant eye first and then see how satisfied the patient was with the near vision. If the patient was happy, I’d put the same lens in the second eye. But I would consider a ZLB00 or even a ZMB00 (both J&J Vision) for the nondominant eye if the patient wanted better near vision. What I found was that mix-and-match was rarely needed and that most patients did very well with bilateral ZKB00 with binocular summation for reading and the least amount of dysphotopsia.
Phase 2: Micro-mono
When the extended depth of focus (EDOF) lens was approved in the U.S., I followed the micro-monovision practice pattern that had emerged outside the U.S., where surgeons had earlier access to EDOF lenses. With that approach, we would implant EDOF lenses in both eyes, targeting plano for the dominant eye and a small amount (approximately –0.3 D) of defocus in the nondominant eye in order to provide patients with a robust range of binocular vision.
The intentional induction of a small amount of defocus did in fact improve the patient’s very near uncorrected acuity. However, increasingly I found that patients invariably preferred the better distance vision in the dominant (plano) eye, stating that their reading vision was more than adequate. This got me thinking that there may be a summation effect in binocular contrast sensitivity when both eyes have very high-quality distance vision, which the Symfony IOL (J&J Vision) provides at distance when targeted for plano. This led to my current approach.
Phase 3: Straddle plano
Today, my go-to presbyopia IOL strategy is to implant bilateral EDOF lenses, aiming for plano in both eyes. As we know, the predicted residual error with a given IOL power is almost never exactly 0 D. Therefore, I choose the IOL power closest to plano but slightly on the plus side for the dominant eye and the IOL power closest to plano but slightly on the minus side for the nondominant eye.
One can certainly achieve good outcomes with any of these approaches, and we will still customize the IOL selection to the patient’s needs when specific. However, I find that straddling plano has increased patient satisfaction, provided excellent binocular distance visual acuity and visual quality, and seems to minimize dysphotopsias.
Disclosure: Waring reports he is a consultant for Johnson & Johnson Vision and a member of the Johnson & Johnson Vision optics advisory board.