Sorting Out Simultaneous Vision IOLs

The ESCRS Eye Journal Club held a webinar hosted by Artemis Matsou MD and Alfredo Borgia MD to discuss the landmark paper, “Evidence-based functional classification of simultaneous vision intraocular lenses: seeking a global consensus by the ESCRS Functional Vision Working Group.”¹ The expert panel included Douglas Koch MD, Daniel Chang MD, H Burkhard Dick MD, PhD, and Joaquín Fernández MD, PhD, lead author of the article under discussion.

Dr Matsou provided a summary of the paper, noting the International Organization for Standardization (ISO) offers the current IOL definitions. However, regarding the simultaneous vision intraocular lens (SVL) categories, the terminology remains ambiguous, with terms like multifocal and EDOF comprising a broad range of lens designs with varying optical designs and functional outcomes. Additionally, there are no defined endpoints for the new enhanced monofocal/monofocal-plus IOLs.

The ESCRS Vision Working Group reviewed scientific literature on SVLs using outcome data. They used cluster analysis to classify SVL IOLs into two main categories: partial range of field (ROF) and full ROF IOLs. Partial ROF is further divided into narrow range (standard monofocal IOLs), enhanced ROF (monofocal-plus IOLs), and extended range of field (EDOF IOLs). Full ROF IOLs are divided based on transition: continuous, smooth, and steep transition.

“The advantages of this classification system are that it focuses on the visual acuity the lenses can achieve across a range of distances based on patients’ experience. And while it recognises an overlap between optical and functional classifications, it is trying to bridge those metrics. There are some limitations,” Dr Matsou said. “For example, it does not include reports on dysphotopsias and patient-reported outcomes, but that is mainly because of the inconsistent reporting of these parameters in the current literature.”

In the discussion that followed, Professor Koch noted the classification system the paper proposes adds further clarity to SVL IOL descriptions, particularly the functional distinctions between monofocal, monofocal plus, and EDOF IOLs, as well as the distinction between steep transition full ROF IOLs versus the smooth and continuous versions. However, he suggested the distinction between the smooth and continuous ROF IOLs may be less clinically relevant.

“Rather than range of field, I would ask that we consider the term depth of field,” he said. “Range of field might invite confusion with some of the newer IOLs, like Pablo Artal’s new lenses, designed to improve range of field in terms of perimetry.”

Dr Chang lauded the ESCRS Functional Vision Working Group’s achievement of adding clarity to IOL definitions amidst a rapidly evolving technology. He noted some factors may require closer consideration, including the conditions under which visual function testing is performed. Variations in testing conditions such as room lighting can influence visual acuity testing, as can the choice of vision charts and the duration and order of testing.

“The most important thing is for us to communicate and, in some ways, think about these things in a consistent fashion because our language doesn’t necessarily define how we think,” he added. “But it helps shape how we think, and how we think shapes what we say.”

Prof Dick noted that when he speaks at German society meetings, the nomenclature for the different IOLs becomes lost in translation. He added an overly complex classification system can be difficult to remember over time, while EDOF and multifocal are well-established terms. However, he noted scientifically basing the nomenclature using defocus curves has the advantage of remaining applicable to new IOL technologies as they become available.

“It is also important to get a sufficient and reliable database,” he said. “And although there is variation in results between individuals that you never will be able to rule out, from a basic point of view, this is a very good step.”

Dr Matsou asked the panel how the scientific societies can work together with industry to convince them to accurately classify the IOLs based on functional outcome data.

“The FDA has strict rules about how to market a particular IOL. Companies do not have as much latitude in how they describe these IOLs as in Europe,” Prof Koch said. “Therefore, we need the ESCRS and the ASCRS to get together and request the manufacturers accurately describe these IOLs in terms of their depth of field.”

“I think most companies work hand in hand with physicians. And I think if we start using the terminology, they will start coming along,” Dr Chang said. “But if we do not agree as physicians, then they will take the reins and use the terminology they want.”

Prof Fernández noted the present landmark paper represents the first step in bringing the classification of simultaneous vision IOLs into accordance with evidence-based medicine.

“A bigger step will be to bring the ASCRS on board with a shared committee to not only consolidate the classifications but [collaborate] in the future as industries introduce new IOL technologies,” he added.

Artemis Matsou MD, MRCP(UK), FEBOS-CR, FEBO, PgDip CRS is a consultant ophthalmologist and cataract lead at Queen Victoria Hospital, East Grinstead, UK. art.matsou@gmail.com

Alfredo Borgia MD, FEBO is based at Royal Liverpool and Broadgreen University Hospitals, Liverpool, UK. alfr.borgia@gmail.com

Douglas Koch MD is Professor and Allen, Mosbacher, and Law Chair in Ophthalmology at The Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, US. dkoch@bcm.edu

H Burkhard Dick MD, PhD, FEBOS-CR is Professor of Ophthalmology and Chairman, Ruhr University Eye Hospital Bochum, Germany. He is also Secretary of the ESCRS. dickburkhard@aol.com

Daniel Chang MD is based at Empire Eye and Laser, Bakersfield, California, US. dchang@empireeyeandlaser.com

Joaquín Fernández Pérez MD, PhD is based at Qvision, Department of Ophthalmology of Vithas Almería Hospital, Spain. He is the incoming Secretary of the ESCRS. joaquinfernandezoft@qvision.es

1. Ribeiro F, et al. “Evidence-based functional classification of simultaneous vision intraocular lenses: seeking a global consensus by the ESCRS Functional Vision Working Group,” J Cataract Refract Surg, 50(8): 794–798.