The latest and greatest research on dual-focus, depth of focus and multifocal contact lenses for myopia control

Before embarking on this educational marathon on soft multifocal contact lens research, it’s important to acknowledge that the reporting of efficacy of myopia is still an area about which we're learning. Specifically, a percentage efficacy is influenced by the length of the study (usually shorter studies = higher %), the age of the control group (younger age = lower %) and the progression rate of the control group (faster = higher %). This is why in the myopia research world, you can sometimes you find yourself comparing apples to oranges rather than eyeballs to eyeballs. There's still a lot more research to be done and things we want to help you understand on this topic, but for now we'll use percentage as our comparison. Let's explore a variety of studies in view of what we've learnt from them - you'll be amazed to see that all of this research has taken place in the last decade so it's a wide ranging but relatively new field.

Arguably the first study of a novel MFCL design, the Dual-Focus Inhibition of Myopia Evaluation in New Zealand (DIMENZ)¹ study in 2011 looked at autorefraction and axial length in forty children. They wore a novel dual-focus contact lens for 10 months in one eye and a single vision distance lens in the other, and then swapped modalities to the alternative eye. The lens trialed had a centre distance design with two alternating concentric zones of distance and +2.00 Add, creating simultaneous myopic retinal defocus. They found a 36% reduction in refractive progression in the dual focus lens, and a 50% reduction in axial elongation. We now know of this lens as the CooperVision MiSight.

Being a single-eye study, the outcomes suggested a strong effect in the treated eye and led to the three-year randomized controlled trial of MiSight which we describe more below.

A novel lens study in 2011, the Decrease in Rate of Myopia Progression with a Contact Lens Designed to Reduce Relative Peripheral Hyperopia: One-Year Results, by Sankaridurg et al. used lenses with an effective peripheral Add of +2.00D. 45 Chinese children aged 7 to 14 followed an eight hour treatment regime and showed a 33% reduction in axial length change and a 30% reduction in myopia progression.² This was compared to 40 controls wearing single vision spectacles. The contact lens wearers only did so for five days per week, which tells us clinically that if patients want to take a weekend break from contact lens wear, that the treatment effect may still be sufficient.

More was learnt about the relationship between wearing time and efficacy in the Defocus Incorporated Soft Contact (DISC) trial. This study evaluated refractive and axial length changes in 221 children with a novel lens incorporating +2.50D of defocus via multiple concentric rings, alternating with the distance correction.³ After observing for two years, the DISC-wearing group had 25% less myopia progression and 31% less axial length progression than the single vision contact lens control group. Interestingly, they found there was an inverse relationship between myopia progression and lens wearing time - the children who wore the lenses for at least 5 hours a day achieved 46% control, while those who wore the lenses for 7 hours or more per day achieved 58% control. There was no additional control benefit after eight hours, suggesting an ideal wearing schedule for MFCLs may be daily wear of at least eight hours.

Presented at ARVO in 2012, Holden, Sankaridurg and co-authors presented the data on a five year MFCL study, one of the longest evaluating treatment effect. Forty children were allocated either the control single vision contact lens or a Test lens design with +1.50D peripheral optical zone and followed for an average of 43 months for the first Phase. In the second Phase, all children wore the Test lens for a further two years.

The 16 children that remained to the end of the five years showed a reduced rate of refractive change by 39% and axial elongation slowed by 41%. The Test MFCL appeared to maintain efficacy over up to 43 months, and the children who were originally in the control group showed similar reduced rates of progression once fitted with the Test lens MFCL.⁴

While this study was small, it demonstrated long term myopia control efficacy of almost 4 years. The longest study currently underway is the MiSight five-year study, where the control group children have been changed out of SV into MiSight for years 4 and 5 of the study.  This data has not yet been published, but we reported on it from the International Myopia Conference 2019 - read more here.

Walline and co-authors were the first to evaluate commercially available MFCLs - typically prescribed for presbyopes - in their 2013 paper Multifocal Contact Lens Myopia Control. Twenty seven (27) children aged 8-11 completed the two year study which used a +2.00D Add CooperVision Proclear Multifocal Distance Centred lens and compared them to an historical SV contact lens wearing control group. It showed a 50% reduction in myopia progression and 29% reduction in axial elongation.⁵

Walline and co-authors recently revealed the long-awaited results of the Bifocal Lenses In Nearsighted Kids (BLINK) study - as it's not open access, this link will take you to our analysis of this key paper. Comparing the CooperVision Biofinity D Centred lens in +1.50 and +2.50 Adds to a single vision contact lens control, the three year study found that the +2.50 Add had a significant effect but the +1.50 Add did not.⁶

If you're planning to use the +2.50 Add in practice, keep in mind that the same authors found that children needed an extra -0.50 contact lens power over their best vision sphere to achive good acuity. Read more on this in Which multifocal soft lens? Refraction and safety.

The CONTROL study in 2016 by Aller et al. evaluated 86 progressing myopes aged 8-18 years, randomized to wear either a commercially available Johnson & Johnson Acuvue concentric bifocal design or single vision contact lenses. The differentiator of this study was that in the test group, the bifocal CL add was selected based on a trial to to neutralize associated esophoria at near. All participants showed near esophoria, and with this tailored approach, over the one-year study the results were some of the highest seen - refractive control was reported as more than 70%.⁷

Since the COMET (progressive addition spectacle lens) study found a greater treatment effect of PALs in children with esophoria and larger accommodative lag,⁸ this may explain why the CONTROL trial had such strong results. It highlights the importance of factoring binocular vision into myopia management. This study also showed that myopia control can be all effective all the way up to age 18, so don’t neglect to offer myopia control to your older patients.

Cheng and co-authors in 2019 published the first paper examining the interaction between accommodation and myopia control efficacy in MFCL. They examined a novel lens design employing positive spherical aberration (effectively a centre-distance design) and demonstrated that the test lens reduced accommodative response, and this reduced response was correlated with a reduced myopia control effect. Interestingly, this relationship wasn’t found in the single vision distance CL corrected control group,⁹ indicating a complex interaction between MFCL optics and accommodation specifically. Reduced accommodation response in MFCL-wearing children¹⁰ and young adults^11,12 has been found by other authors too, although it may vary across lens designs.¹²

There's still a lot to learn about how MFCL influence binocular vision in young wearers and how this could relate to myopia control efficacy. For now, these studies highlight the importance of assessment and management of a patient's binocular vision system - to ensure visual comfort and, as we learn more, perhaps optimize myopia control efficacy.

Read more about Four reasons binocular vision matters in myopia management here.

In 2015 Paune and co-authors evaluted myopia control with a novel peripheral gradient soft lens (SRRG) compared to orthokeratology in a two year trial.¹³ This study monitored participants for twelve months before commencing treatment with a novel soft contact lens with an increasing continuous add power of +2.00 Add "at 35 degrees of retinal eccentricity and... about +6.00 D of additional plus power at the end of the optical zone (4mm semichord diameter)."

The study showed a 43% reduction in myopia progression when wearing the novel soft lens and a 67% when wearing the OK lens. While the percentages look different, the absolute refractive differences of 0.42D less myopia after two years in SRRG and 0.66D less in OK wearers, compared to SV, were not significantly different. This was confirmed when looking at the axial length data, which was also similar in SRRG and OK. This is the only currently published trial which directly compares a MFCL and OK, so affirms that both have similar efficacy for myopia control. Read more about this in Myopia Management Message Part 2- Efficacy.

Presented as an abstract at ARVO 2018, Cheng, Xu and Brennan presented data on a 'simOK' soft contact lens compared to a single vision spectacle control. After one year, axial length was slowed by only 9% and there was no change in refraction. Since it was only an abstract, the 'simOK' design which was stated to "simulate the optical impact of OK on the eye" was not described any further. It is not known if the anterior optical profile or peripheral refraction changes after OK were sought, or how they were evaluated. The fascinating conclusion from the authors was that "the mechanism by which OK imparts myopia control may not be optical in nature". Our view - we'd need to understand more about the simOK lens design and how it was validated against a similarly powered OK lens to see if the optics were indeed similar or not.

Cheng and extra co-authors have recently presented more data on the simOK lens, this time in an abstract for ARVO 2020. They evaluated aberrometry in patients wearing simOK compared to OK-treated eyes, and found a similar increase in positive spherical aberration at distance, with both significantly higher than bare-eye measurement (no OK treatment or SCL wear). Results were similar at near, showing increases in near total 3rd and higher order aberrations. The authors concluded that given these optical properties are similar but the simOK lens didn't control myopia (while OK does), "additional analysis of off-axis refraction and accommodative response with the simOK lens will be examined."

A novel lens design was developed by Fujikado and their team in 2014, where the central viewing portion of the lens was decentred nasally, and the add power of the periphery was equivalent to +0.50D of defocus.¹⁴ For the first 12 months the 24 children aged 10-16 years were randomised to either the novel lens or a single vision distance contact lens, then treatment protocols were crossed over for the final 12 months. They found no significant difference in reduction of myopia progression between the two groups. This is one of the lowest amounts of MFCL optical add power investigated, and while it was a small study, suggests the higher adds may be more effective.

The Cambridge Anti-Myopia Study (CAMS) looked at a different novel lens design which used "aberration controlled contact lenses to reduce the lag of accommodation." Testing the theory of improving accommodative function for myopia control, it also employed vision training (lens flipper exercises) to additionally improve accommodation dynamics. The group of 96 participants were aged 14-22 years at baseline and refractive error up to -10D. They found no significant effect of either treatment. The mean age of around 16 years likely explains the minimal findings, along with their lens design incorporating negative spherical aberration to support accommodation¹⁵ (think of this as a centre-near lens), which is at odds with most other MFCL designs which employ or induce positive spherical aberration (think of this as a centre-distance design).

Another novel lens concept which showed a short term effect on axial length but not on refraction was investigated by Cheng and co-authors in 2016. The amount of positive spherical aberration was "chosen to negate the negative SA that occurred in myopic subjects during accommodation (based on internal unpublished data)." An effective 'add' value is not cited. In 127 participants aged 8-11 years, they found 65% less axial progression after 6 months and 39% less after 12 months. Myopia progression was 54% less at 6 month but there was no difference at 12 months. They then followed 82 of the participants for an additional 1.5 years wearing SV contact lenses and found at the end that there was no difference in final rate of axial or refractive change between the two groups.¹⁶ This confirms a lack of rebound effect in MFCL wear, as well as the complexity of axial versus refractive percentage changes.

Sankaridurg and co-authors tested four novel lenses in their 2019 paper Myopia control with novel central and peripheral plus contact lenses and extended depth of focus contact lenses: 2 year results from a randomised clinical trial on 58 children over two years.¹⁷ The lenses had varying profiles, two with more “traditional” multifocal profiles with relative plus power in the periphery of +2.50D and +1.50D, and two with "extended depth of focus incorporating higher order aberrations to modulate retinal image quality". These latter two lenses were described as providing up to +1.75D and +2.50D depth of focus. The “traditional” multifocal profiles slowed progression by 24%, in a dose dependent manner where the effect was greater (up to 39% refractive control) when the lenses are worn for at least six days a week. The novel lens designs showed 32% and 26% efficacy, suggesting that the extended depth of focus designs were more effective - ie. the type of defocus, more so than the power, has a greater influence on control. This extended depth of focus or 'EDOF' technology is employed in the commercially available Mylo lens from Mark'ennovy for myopia; and the SEED 1dayPure EDOF lens for presbyopia.

NaturalVue lenses were studied by Cooper et al. in a multi-practice trial of 32 patients, with a follow up range of 6 to 25 months and an average of 10 months.¹⁸ The children entering the study weren't randomized - they'd had a number of prior treatments which were "not successful in slowing myopia progression", being defined as at least -0.5D of progression since their previous examination.

The case series study found that 98% of children had a reduction in their myopia progression, with 81% having complete halting of change. They also suggested that 6% of children had a refractive “regression” with the lenses. 91% of children had a 70% decrease in their progression or more. While this is promising data, it's important to note the key significant limitations of this study in comparison to others presented here.

1. There was no control group - the children's prior progression rate, with a variety of treatments, was used as a comparison. Progression tends to decrease with time anyway, regardless of treatment,¹⁹ so this is somewhat spurious.
2. The primary outcome measure was refraction, but it's not known if this was cycloplegic, subjective, objective or otherwise - it wasn't standardised across the 10 sites involved in data collection.
3. There are no axial length measurements.

This study does likely reflect the realities of clinical practice - a treatment doesn't work so we'll try another one - and it likely indicates that NaturalVue worked better for these children than their prior myopia corrections or control treatments. About 80% of these children were in SV corrections before the switch to NaturalVue, so the significant slowing of myopia progression is noteworthy, while keeping the limitations in mind when comparing to other studies.

MiSight lenses were initially studied in 2011 by Anstice and Phillips with a 36% reduction in myopic change in a crossover (one eye at a time) study, as discussed above. They were again evaluated in 2018 by Ruiz-Pomeda et al. on 8 to 12 year olds over a 2 year period. These authors compared these dual-focus to single vision spectacle lenses. Over the 2 year period the MiSight group had a 39% reduction of their myopia progression and 36% reduction in axial elongation. Wearing time compliance was high - the study protocol recommended 6 days of wear a week, and the children adhered and exceeded this with an average of 6.3 days of wear, 12 hours a day during the week and 7 hours a day on the weekend reported at their 12 month visit. No relationship was found between wearing time and efficacy.²⁰

MiSight lenses were again studied by Chamberlain et al. in 2019 comparing them to single vision contact lens of the same material.²¹ It was performed across four sites in Singapore, Canada, Portugal and the UK. Children were between 8 and 12 years at commencement of the study and randomised into the MiSight or control, with outcomes including cycloplegic refraction and axial length. After 3 years the myopic refraction control effect was 59%, and axial length control was 52%. The first year of treatment showed a slightly higher level of refractive myopia control of 69%. They also surveyed the children on their experience wearing the lens, with 97% having a positive attitude toward their lens wear.

There is still much to learn about MFCLs - the various lens designs and adds employed in studies indicate that a lot of these options work. Their mechanism of action - whether it be simultaneous vision through concentric designs, changes in spherical aberration, altering peripheral refraction or other - is still under investigation.

For commercially available lenses where multiple add powers are available, we are yet to learn which is best. The impending results of the BLINK study will answer the question of comparing +1.50 and +2.50 Adds in the CooperVision Biofinity "D" (centre distance) design. Caution should be taken in extrapolating this to other lens designs which haven't been researched - as you've hopefully learnt from the above, the optics is complicated and all MFCL aren't created equal!

We also have no myopia control studies undertaken yet on toric MFCL corrections. The only toric myopia control contact lens studies undertaken are those investigating orthokeratology, showing similar results to spherical OK in children with -1.25 to -3.50D of astigmatism. Read more in Prescribing for the progressive myope with astigmatism.

• Which multifocal soft lens? Efficacy and visual function

• Which multifocal soft lens? Refraction and safety

• Case study: Which soft multifocal contact lens to choose?

• Case study: Selecting a contact lens for astigmatic myopia