Understanding the HOYA MiYOSMART spectacle lens performance

The first publication of the new wave of effective myopia management spectacle lenses reported on the Defocus Incorporated Multiple Segments (DIMS) spectacle lens. Known under the commercial name MiYOSMART, this spectacle lens was developed by Hoya Corporation in cooperation with researchers from the Hong Kong Polytechnic University. Two-year randomized controlled clinical trial (RCT) and three-year follow up clinical study data have been published,^1,2 and six-year data has been reported,³ making this the longest running study on spectacle lenses for myopia management.

The six-year data for the DIMS spectacle lenses are yet to be formally published; however, preliminary results of trial are positive. 90 children ended up completing the six-year trial, from the initial 183 children that were involved in the published two-year data.³ The two-year data^1,2 for MiYOSMART showed that there was an average 59% myopia control effect in the cycloplegic spherical equivalent refraction and 60% in axial length. Six year data shows that this effect is sustained, and early indications also suggest there is no rebound effect after cessation of MiYOSMART and uptake of single vision lenses.³ 

The description of the lens design from the two-year clinical trial paper includes the following detail.¹

• A central zone 9.4mm in diameter that provides full refractive correction in the form of a single vision lens surface
• An annular multiple focal zone (the "treatment" zone) of 33mm in diameter comprising of 396 segments and surrounds the central zone
• Each segment in the treatment zone is 1.03mm in diameter and has a relative positive power of +3.50D
• These segments are arranged in a honeycomb array, which allows for some distance correction in between the segments
• The treatment zone is designed to introduce myopic defocus constantly (when viewing both distance and near objects).

The lens is based on the simultaneous defocus theory of myopia.^1,2 Animal studies have demonstrated that eye growth can be arrested by myopic defocus and promoted by hyperopic defocus.⁴ The DIMS spectacle lens is a dual-focus design that creates conflicting signals that allow for simultaneous retinal defocus. The first focussing feature is the single vision central zone which allows visual information to fall onto the retina providing clear vision. The second focussing feature are the circular segments of plus power which makes visual information fall in front of the retina and hence creates myopic defocus.

These segments, with their relative plus power, create myopic defocus and are systematically scattered around the lens in a 360-degree manner. This provides a potent slowdown signal, which is maintained in all directions of gaze.

The two-year RCT data was published in May 2019. The study included 183 Chinese children aged 8-13 years with myopia between -1.00D and -5.00D and no more than -1.50DC astigmatism. 93 children were randomly assigned the DIMS spectacle lens and 90 children received single vision (SV) spectacle lenses. Cycloplegic autorefraction and axial length were measured in 6 monthly intervals. 79 children from the DIMS group and 81 children from the control group completed the RCT. The results were as follows.¹

• Myopia measured by refraction progressed 59% more slowly in the DIMS group vs the SV group
• Myopia measured by axial length was 60% less in the DIMS group vs the SV group
• 21.% of children who wore the DIMS spectacle lenses exhibited no signs of myopia progression over the 2 year period

In the three-year follow up clinical study, the slow down effect was sustained. Those in the SV group were switched to DIMS spectacle lenses, and it was found that their myopia was slowed significantly once switched to DIMS.²

Due to COVID-19, the school of optometry study site was closed and the study was on hold. The six-year follow-up clinical study data was a continuation of the initial two-year RCT and three-year follow-up clinical study completed after the lockdowm. The children involved in the study were followed up and divided into four groups.³

• Group 1: children who wore the DIMS spectacle lenses for the full six-year duration
• Group 2: children who worse the DIMS spectacle lenses for 3.5 years and switched to SV spectacles
• Group 3: children who wore SV spectacles for the first 2 years of the trial, then switch to the DIMS spectacle lenses and wore for 4 years
• Group 4: children who wore SV spectacles for the first 2 years of the trial, then switch to the DIMS spectacle lenses and wore for 1.5 year, then switched back to SV spectacles.

The six year data signifies three important findings. These are:

1. The myopia control effect of the DIMS spectacle lenses is sustained over 6 years. Group 1 experienced myopia progression of -0.92D and 0.6mm for refraction and axial length respectively over the entirety of the 6-year study course.
2. There is no evident rebound effect when switching to SV spectacles. Groups 2 and 4 experienced an increase in eye growth when switching to SV spectacle lenses; however, this was at age normal rates.³
3. No adverse event was reported over 6 years

When measuring high contrast and low contrast visual acuity at distance and near, stereoacuity, and phorias, the DIMS spectacle lenses did not appear to affect these measurements after two years of wear.⁵ Accommodative lag and both monocular and binocular amplitude of accommodation appeared to decrease after two years; however, this occurred for both children wearing DIMS spectacle lenses and SV spectacle lenses.⁶

A study by Lu et al in 2019 recruited 20 children to wear the DIMS spectacle lenses; the main visual complaint from the study participants was a decrease in mid-peripheral vision caused by the treatment zone which was noticed on average once or twice a day. However, 90% of the study participants preferred the DIMS spectacle lenses over SV spectacle lenses, after being made aware of its anti-myopia properties. It appears that if children are educated on the DIMS spectacle lenses, they tend to tolerate and accept them well.⁷

MiYOSMART is effective at slowing down myopia progression. However, three important factors must be met to ensure that clinical success matches that found in the research studies.

1. Wearing time: in the study, participants were asked to wear the spectacle lenses "full-time": that is, constantly except when they took a shower or when sleeping. This averaged to about 15.5 hours per day, 7 days a week.¹ Hence, wearing time is important to maximize the myopia control benefits.
2. Frame fit: it is important that the wearer feels comfortable in the spectacles and they fit well. Movement of the frame may affect visual acuity, when the eye is not seeing through the central clear zone; or even result in the child spending some time looking over the top of their lenses if the frame slips downwards.
3. Lens fitting heights: just as it's important to get the frame fit correct so that the spectacles are comfortable and the wearer is looking through the central clear zone most of the time, accurate height measurements are essential for ensuring that the central clear zone sits in front of the pupil.

• Science Review: Two Year Clinical Study Outcomes For The Defocus Incorporated Multiple Segments (DIMS) Spectacle Lens

• Science Summary: Three Year Follow Up Clinical Study Results Of The Defocus Incorporated Multiple Segments (DIMS) Spectacle Lens

• Ryu H, Ju U, Wallraven C. Myopia-correcting lenses decrease eye fatigue in a visual search task for both adolescents and adults. PLoS One. 2021 Oct 13;16(10):e0258441. 

PRODUCT DISCLAIMER - MiYOSMART has not been approved for myopia management in all countries, including the U.S., and is not currently available for sale in all countries, including the U.S.