CLINICAL DEVELOPMENT of soft multifocal contact lenses (MFCLs) has rapidly evolved and they are now very popular—and not just with baby boomers and presbyopes. Their application has become increasingly versatile for patients of all age groups, particularly for the pediatric population (Walline et al, 2013; Sankaridurg 2017; Li et al, 2017).

Notably, in the double-masked, three-year Bifocal Lenses In Nearsighted Kids (BLINK) randomized clinical study (Walline et al, 2020), it was found that multifocal contact lenses with high add power (+2.50D) outperformed the medium add and single vision groups in halting myopia progression, with the largest difference in progression by 0.46D and -0.23mm in refractive error and axial length growth, respectively. Recently, a soft MFCL has demonstrated remarkable cumulative treatment effects, halting axial length growth by 71% over a three-year period (Chamberlain et al, 2022).

While MFCLs have shown tremendous value and potential, the underlying mechanisms have yet to be conclusive. A hypothesis was suggested that MFCLs help reduce accommodation demand, which depends more on the unique lens design than on the labeled “add” power (Gifford et al, 2021). Meanwhile, a recent follow-up study by the BLINK2 Study Group has demonstrated no clinically significant differences in accommodative functionality, including amplitude, lag, or facility among children after nearly five years of multifocal lens wear (Chandler et al, 2023).

In addition, a novel lens geometry that has a multi-zone design combining coaxial and non-coaxial zones was found to influence the magnitude of myopic defocus, mostly across the central +30º of the retina (Sah et al, 2023). This finding was also supported by a recent study that provides another glimpse at how dual-focus contact lenses might impact myopic eyes (Turnbull et al, 2023). The authors reported that the amplitudes and latencies of the global flash multifocal electroretinogram (gmfERG) responses induced by dual-focus lens design were shown to be at the highest level within the central 10º of the retina, suggesting that the central retina likely plays a bigger role in mitigating myopia progression than previously thought.

The subject of soft lens centration is less commonly discussed, since it is often perceived that the diameters of most soft contact lenses generally overlie the entire horizontal visible iris diameter. Nevertheless, when fitting patients with soft MFCLs, particularly those who have a toric component involved, the concern of lens decentration should not be overlooked or simplified.

Soft lens decentration could result in undetectable prism imbalance with vertical coma and thus negatively influence visual performance and patient satisfaction (Sulley et al, 2015; Fedtke et al, 2016). In fact, most toric SCL designs utilize vertical prism-ballast, which has been associated with higher-order aberrations (HOA) (Berntsen et al, 2009; Demir et al, 2015; Caprena-Torres et al, 2018).

Interestingly, HOAs have recently emerged as a novel “impetus” in slowing axial length elongation for children treated with orthokeratology (Vincent et al, 2020; Lau et al, 2020). Despite various potential mechanisms being involved; it is hypothesized that HOA designs will likely be part of the next wave in soft MFCL advancement.

References

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3. Li SM, Kang MT, Wu SS, et al. Studies using concentric ring bifocal and peripheral add multifocal contact lenses to slow myopia progression in school-aged children: a meta-analysis. Ophthalmic Physiol Opt. 2017 Jan;37:51-59.
4. Walline JJ, Walker MK, Mutti DO, et al; BLINK Study Group. Effect of High Add Power, Medium Add Power, or Single-Vision Contact Lenses on Myopia Progression in Children: The BLINK Randomized Clinical Trial. JAMA. 2020 Aug 11;324:571-580.
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