Myopia Profile

Clinical

5 years of the Essilor® Stellest® lens - Q&A with Dr. Björn Drobe and Prof. Mark Bullimore

Posted on July 9th 2024 by Professor Mark Bullimore

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In this article:

The 5-year clinical trial data on the Essilor® Stellest® lens indicate long-term efficacy of HAL lenses for managing myopia - you can read more about how they work in our article Understanding the new Essilor® Stellest® spectacle lens. We speak to Dr. Björn Drobe, director of R&D Vision Science Asia at EssilorLuxottica , and Professor Mark Bullimore, adjunct Professor at the University of Houston School of Optometry, about the latest data on the  Essilor® Stellest®  lens and the future of research in myopia management. 

Can you please explain the outcomes/findings of the 5-year study on spectacle lenses with highly aspherical lenslets (HAL)?

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We recently presented the results of the five-year clinical trial of spectacle lenses with highly aspherical lenslets (HAL) at the Association for Research in Vision and Ophthalmology (ARVO) annual meeting in Seattle. The results demonstrated continued long-term efficacy of the lenses in controlling myopia progression and axial elongation over five years. Essilor® Stellest® lenses are based on the optical design of HAL lenses. The controlled, prospective, randomized clinical trial began in 2018 and was conducted at the Eye Hospital of Wenzhou Medical University in Wenzhou, China with children aged between 8 and 13 years old. 

 To be able to assess the long-term efficacy and whether the lenses would still be effective in slowing down myopia progression in older children, the study was extended first from 2 to 3 years and then onto year 4 and 5 of the clinical trial. The five-year data showed that Essilor® Stellest® lenses slowed myopia progression by 1.75D*2 and axial elongation by 0.72mm**2 on average over five years for all subjects, compared to the extrapolated control group. The children who completed the fifth year follow up were aged between 13-18 years by then, so Essilor® Stellest® lenses remained effective in slowing myopia progression in older children, up to 18 years old. It is planned to continue the study for two more years, to gauge the 7-year myopia control efficacy of the lens.  

*Compared to the 60-month progression of the extrapolated control group (predicted average annual decrease in SER by 9.7% based on the initial 2-year control group, Smotherman C, et al. IOVS 2023;64:ARVO E-Abstract 811).   

**Compared to the 60-month progression of the extrapolated control group (predicted average annual decrease in AL by 15% based on the initial 2-year control group, Shamp W, et al. IOVS 2022;63:ARVO E-Abstract A0111)  

How was the efficacy of HAL spectacles impacted by wearing time or baseline factors?

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Research has shown that full-time wear (at least 12 hours per day) should be encouraged for children to potentially maximize myopia control outcomes. The effect of wearing time on myopia control efficacy of spectacle lenses with HAL indicated a dose-response relationship, increasing myopia control efficacy for full-time wearers (at least 12 hours per day)1, demonstrating that wearing time matters in myopia control. 

 HAL lenses slowed down myopia progression by 0.80D (55%) and axial elongation by 0.35mm (51%), on average, compared to single-vision spectacle lensesover two years. Myopia control efficacy increased with wearing time for HAL lenses, reaching 0.99D (67%) less myopia progression and 0.41mm (60%) less axial elongation on average over two years for full-time wearers, when compared to single vision spectacle lenses1. This clearly shows that there is greater efficacy when the lenses are worn more than 12 hours per day every day, than when worn less than 12 hours per day. Hence, full-time wear of a myopia control solution such as Essilor® Stellest® lenses should be encouraged for children, to maximize myopia control outcomes.

 Aside from this, a recent publication in Ophthalmic and Physiological Optics journal has shown that after the first and second year, the eye growth of 9 out of 10 children wearing Essilor® Stellest® lenses full time was similar or slower than non-myopic children.3  

Can you tell us what you’ve learnt about the potential rebound effect with HAL spectacle lenses?

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A one-year crossover clinical trial led by Brien Holden Vision Institute in collaboration with our R&D team and Hai Yen Care Institute, Vietnam, evaluated the progression of myopia in 119 Vietnamese children wearing HAL lenses versus standard single-vision lenses.  It also allowed us to evaluate whether rebound of myopia progression upon discontinuation was observed. The children were aged 7-13 years, with a myopic prescription between -0.75 to -4.75D and were randomized to wear either HAL lenses or single vision lenses. After 6 months, they crossed over, so the HAL lens group was now wearing single vision lenses for the next 6 months and hence, any rebound effect could be measured. Children were compliant with lens wear; an average of 14 hours per day of lens wear was reported with both lenses. The data was not suggestive of rebound when patients were switched from HAL lenses to single vision lenses.4 The efficacy comparisons also confirm that HAL lenses slowed myopia progression compared to single vision lenses.

Can you talk about the extrapolated control group in the fourth and fifth year of the study? What is its significance?

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In the fourth and fifth year of the study, 43 out of 51 children who wore HAL lenses continuously for three years accepted to be followed for two more years and completed the fourth year and fifth year follow-up. For year four and five, there was no control group for ethical reasons, as the new single vision lens group recruited for the third year were given a pair of HAL lenses at the end of the third year. Instead, an extrapolated control group was used for the fourth and fifth years, based on a model proposed by Shamp et al.1,5 in which mean axial elongation decreases as age increases, by 15.0% per year and a model proposed by Smotherman et al.6 in which SER decreases by 9.7% per year on average.  Shamp et al. and Smotherman et al.’s models were applied to the initial control group that participated in the two-year randomized clinical trial.  An average decrease of change in axial length by 15% per year and an average decrease in SER by 9.7% per year was applied to this single vision lens group data from the first two years of the clinical trial.  

 The accuracy of the extrapolated control group was assessed by comparison to the single vision lens group that was matched to the initial control group at the end of the second year. It was found that myopia progression and axial elongation in the extrapolated control group was very comparable to the actual change of axial length and myopia progression during the third year with these real-life recruited age matched controls. Thus, Shamp et al.’s and Smotherman et al.’s models were validated by comparing against the third-year single vision control group. These models proposed by Shamp et al. and Smotherman et al. could be valid options for avoiding placebo control groups if prior change in axial length and myopia progression are available.

What approach should be used to compare the efficacy of different myopia control solutions?

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The efficacy of different myopia control modalities can be evaluated in terms of myopia progression in dioptres or axial elongation in millimetres. Axial length is preferred due to its greater precision and because refractive error cannot be accurately assessed during orthokeratology and can be influenced by atropine. 

 At present, there are different metrics for presenting efficacy of a myopia control treatment. Percentages should be avoided because they are very dependent on the age and race of the  participants. Brennan et al. recognized that the optimal way to express efficacy observed with   myopia control solutions is Cumulative Absolute Reduction in axial Elongation (CARE).7 This is  reported by most clinical trials and is a simple and clear metric. 

 CARE provides relevant insights into the success of myopia control solutions by evaluating the actual reduction in axial elongation over time. Moreover, unlike other metrics, such as percentages, CARE is unaffected by age and ethnicity, so values from one study can be applied to other populations. For Essilor® Stellest® lenses, the CARE value is 0.49 mm over three years, higher than any other optical treatment, and 0.72 mm over 5 years, placing it among the most effective options.

What do you think is the future of design for long-term efficacy clinical trials?

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Last year we published a paper identifying some of the challenges of conducting conventional randomized clinical trials of myopia control.8 For example, we have to ask ourselves whether it's ethical to withhold myopia control treatment from children 9 for the duration of a three-year trial. Likewise, there are practical challenges of recruiting and retaining children when myopia control modalities are becoming available. 

We proposed a number of solutions including non-inferiority trials where an approved drug or device is used as a control.8 Here all children receive some form of treatment. Two other potential solutions were the creation of a virtual control group based on our meta-analysis where age and ethnicity are accounted for. The challenge here is that any cohort of children recruited for a study may show differences from historical cohorts because of the setting and potential recruitment biases. A preferred approach is to recruit a control group for a short period of time, perhaps one or two years, and after that time, put them on treatment. The control group data can then be extrapolated to future years assuming a slowing of axial elongation of 15% per year.

What is your view on the use of extrapolated control groups?

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A number of papers have successfully leveraged this approach. For example, we examined the three-year data from the LAMP study10 where there were only one year of control data.11 By applying the 15% slowing per year, we were able to extrapolate the control group to three years and thus estimate the three-year efficacy of the three different concentrations of atropine. Likewise, the investigators of the MiSight dual-focus contact lens were able to estimate the six-year efficacy of the lens by taking three years of data on control subjects wearing single vision soft contact lenses and extrapolating their axial elongation through six years.9 In summary, this approach offers a solution to the ethical challenge of withholding treatment for several years.

What factors need to be considered for using extrapolated control groups in clinical trials?

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It is important to recruit a robust sample size and to carefully randomize the children to either treated or control groups. If randomization is not performed, this can lead to bias as parents may elect to choose the treatment or single vision spectacles based on unknown factors. It is also important to recruit and retain a meaningful number of control subjects. We know from recent clinical trials that any withdrawal of some subjects may lead to bias as those withdrawing may have above average rates of progression, leaving the retained subjects with a lower rate of progression, again leading to bias.12 A final concern is that the parents of control group children may seek myopia management options outside of the study.

What are the other latest findings on HAL lenses?

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We performed several studies with HAL lenses to observe their impact on other factors such as choroidal thickness, corneal astigmatism, peripheral and central eye elongation, and more. For example, we conducted a study based on the two-year randomized clinical trial with HAL lenses, to explore the changes in cylinder power and corneal astigmatism in myopic children wearing HAL lenses and to compare these findings with myopic children wearing single-vision lenses (SVL). 

 In this study, a total of 103 eyes in 52 children from the HAL group and 98 eyes in 49 children from the SVL group completed all examinations and were included in the analysis. The HAL group demonstrated significantly slower myopia progression and change in axial length, compared to the SVL group. The study concluded that after two years, wearing HAL lenses had no significant impact on cylinder power and corneal astigmatism compared to single vision lenses.13

 In addition to this, we also conducted another study to examine the effect of wearing HAL lenses for three years and whether switching from single-vision lenses to HAL lenses exhibited any changes in choroidal thickness. The key outcomes from the study were that during the third year, children who consistently wore or switched to wearing HAL lenses demonstrated significantly less choroidal thinning compared to children wearing single vision lenses.14 

 Aside from this, we also wanted to explore the effect of HAL lenses on the peripheral eye length changes in Chinese myopic children. We presented an abstract at ARVO on this study as well. We observed that HAL lenses were effective in slowing down both central and peripheral eye elongation. Similar elongation rates were observed in children wearing HAL lenses, thus preventing the eyeball from growing towards a more oval shape.15


Meet the Authors:

About Professor Mark Bullimore

Professor Mark Bullimore is an internationally renowned scientist, speaker, and educator based in Boulder, Colorado. He received his Optometry degree and PhD in Vision Science from Aston University in Birmingham, England. He has spent most of his career at the Ohio State University and the University of California at Berkeley and is now Adjunct Professor at the University of Houston. He is the former Editor of Optometry and Vision Science and former Associate Editor of Ophthalmic and Physiological Optics. His expertise in myopia, contact lenses, low vision, presbyopia, and refractive surgery means that he is a consultant for a number of ophthalmic, surgical, and pharmaceutical companies.

About Dr. Björn Drobe

Dr. Björn Drobe is the Director of R&D Vision Science Asia at EssilorLuxottica, focusing on myopia control. His educational background includes a B.Sc. in Optometry, an M.Sc. in Cognitive Sciences, and a Ph.D. in Vision Sciences from Paris, France. Before his current role, he joined Essilor's R&D team in 1998, dedicating his research to understanding the effects of ophthalmic lenses on the human visual system and developing solutions for progressive myopia in children.


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