Reversible Multifocality

The combination of trifocal supplementary IOL in the ciliary sulcus and monofocal capsular bag IOL is a fully reversible means of providing the same range of focus as standard trifocal IOLs for capsular bag implantation without significant loss of optical quality and no disadvantages due to additional interfaces, said Ramin Khoramnia MD.

“What I really like about the two-lens combination approach is it is currently the only available technique we have when it comes to [achieving] a reversible multifocality,” he said. “The advantage of this approach is that later on, if ever required, we can remove the supplementary IOL from the sulcus—which is certainly much easier than removing the IOL from the capsular bag.”

The two-lens approach first involves implanting a primary monofocal or toric IOL into the capsular bag, then placing a supplementary trifocal IOL in the ciliary sulcus. Unlike the piggyback lenses of the past designed for implantation into the capsular bag, supplementary IOLs don’t touch the primary lens in the capsular bag; therefore, there is no risk of interlenticular opacities or iris chafing.

The supplemental IOLs on the market include the Sulcoflex (Rayner) trifocal IOL, made of a hydrophilic material with good uveal biocompatibility, and the AddOn (1stQ). AddOn’s main advantage is four-point fixation, providing very good rotational stability—especially important with toric supplementary IOLs.

One concern regarding the use of two lenses is the possible optical and light transmission effects of the additional interfaces. Dr Khoramnia and his associates, therefore, conducted an optical bench study comparing a two-lens combination of the Sulcoflex trifocal (IOL703F) and RayOne aspheric (RAO600C) with a one-lens system using the RayOne trifocal IOL (RAO603F). They found the modular transfer function (MTF) curves of the two-lens and one-lens optical systems matched closely, the Strehl ratios were very similar, and light transmission decreased by 1.3%.

The reversibility of supplementary trifocal IOLs means they are suitable for patients who desire multifocality but have minor ocular abnormalities or are young with a less predictable profile regarding future ocular pathology.

As an illustration, he presented his findings from a study involving 25 cataract and refractive lens exchange patients who underwent the Duet procedure. The motivations for the choice of a reversible procedure included patients aged 18 to 38 years, elevated risk of deviation from the target refraction, subtle morphologic changes without a clear contraindication for a trifocal optic, and borderline binocular function.

“Despite the fact that we had certain reasons to offer a reversible multifocality in these patients, we never had to remove a trifocal supplementary IOL in this series,” Dr Khoramnia said. “And we achieved excellent visual acuity in the far intermediate, and near 0.2 logMAR or better was achieved up to almost 3.75 D of defocus.”

Dr Khoramnia presented his paper at an ESCRS eConnect Webinar, “Evidence-based overview of current premium IOL technologies.”

Ramin Khoramnia MD, FEBO is a surgeon based at the International Vision Correction Research Centre (IVRC), a laboratory leader at The David J Apple International Laboratory for Ocular Pathology, and a professor in the department of ophthalmology, Ruprecht-Karls University of Heidelberg, Germany. Ramin.khoramnia@meduni-heidelberg.de