Title: Myopia Progression in Children wearing Dual-Focus Contact Lenses: 6-Year Findings
Authors: Paul Chamberlain (1), Baskar Arumugam, Debbie Jones, Nicola Logan, Sofia Peixoto de Matos, Graeme Young, Chris Hunt, Cheryl Ngo
- CooperVision (only lead author affiliation stated)
Reference: American Academy of Optometry meeting abstracts (Link to abstract)
Following from the 3 year MiSight study results, published in 20191 and detailed in a recent Myopia Profile Review [MiSight 3-year data analysis], the authors continued the study out to 6-years with the initial MiSight wearing cohort (M1D-6) continuing lens wear and initial control cohort (M1D-3) who were refitted from single vision soft contact lenses (control intervention) to MiSight. The authors compared the myopic progression of the two groups over years 4-6, now all wearing MiSight, and did not find a statistically significant difference in spherical equivalent refraction or axial length.
The apparent change in slope in the MID-3 cohort, where from the reported results myopia progression appears to progress at a slower rate after switching from single vision lenses to MiSight, suggests that MiSight provides a noticeable myopia control benefit when fit to older children. For the MID-6 cohort wearing MiSight for 6 years, the lack of significant difference between the two cohorts over years 4-6, when taking into consideration the apparent slowing of myopia progression seen in the MID-3 cohort on starting MiSight wear, implies that MiSight continues to provide a myopia controlling effect beyond 3 years of wear.
There was no statistically significant difference in change to myopia over the 4 to 6 year study period between the two groups, for either SER (p=0.1) or AL (p=0.4).
- M1D-3: SER -0.29D (CI -0.17 to -0.42), AL 0.18mm (CI 0.13 to 0.24)
- M1D-6: SER -0.44D (CI -0.31 to -0.58), AL 0.22mm (CI 0.16 to 0.28)
- The lack of difference between the two groups indicates that older children (11-15 years) with greater myopia and axial lengths (M1D-3) progressed at a similar rate over 3 years to those who were treated for 6 years (M1D-6)
- This result is very interesting, as it is in dichotomy to a recent publication by Brennan et al (2019)2 who reported that children gain the greatest treatment effect from myopia control in the first year of treatment, which subsequently declines with time.
- This being the case it would be expected that the M1D-3 group should gain a superior treatment effect in comparison to the M1D-6 group, as they are “new wearers” in years one, two and three of treatment with MiSight. As the M1D-6 group are “existing wearers” in their fourth, fifth and sixth year of treatment with MiSight, we would anticipate a declining, and perhaps minor treatment effect.
- The lack of a non-treatment control makes it difficult to determine if the M1D-3 group experienced an inferior treatment effect, or if the M1D-6 group experienced a superior treatment effect, such that both are not statistically different from each other.
- Nonetheless, Eye care practitioners can use this information to fortify their decision in commencing MiSight wear in older children (11-13 years), and also to continue long-term treatment with MiSight in those that started wearing MiSight at a younger age, with some assurance that, from the presented 6-year results, the treatment appears to remain effective.
Limitations and future research
The differences between the 2 groups at baseline of Part 2 complexifies the interpretation of the results.
- At commencement of Part 2, the M1D-3 group had statistically significantly longer eyes (p=0.02) and more myopia (p=0.001). Subsequently, it is likely that at initiation the two groups had differing rates of progression. The disparity in myopia control efficacy witnessed in children with varying degrees of myopia and rates of progression is debated in literature. It was previously believed that higher myopes/faster progressors gain a superior treatment effect, however this theory was recently challenged by Brennan et al (2020).2
- In a recent hallmark paper, it was proposed that there is insufficient evidence to assert that faster progressors experience greater treatment efficacy. Read further about how to assess the efficacy of myopia control treatment
- Nonetheless, the disparity in levels of baseline myopia at commencement of Part 2 complicates the interpretation and direct comparison of the obtained results obtained
- Additionally, it is likely that the efficacy observed in the M1D-3 group is increased, due to this group advantaging from the “first year of treatment” effect described by Brennan et al (2020)2
- It is widely reported that the greatest treatment effect is observed in the first year of treatment. In Part 2, the M1D-3 group were in their first, second and third year of treatment with MiSight 1 day, while the M1D-6 group were in their fourth, fifth and sixth year of treatment.
- While the isolated treatment effects for these two groups are genuine, it may not be appropriate to compare the two directly
- Lack of a control ‘non-treatment’ group makes it difficult to ascertain whether the MID-6 group continued to benefit from a myopia controlling effect after 3-years of lens wear or whether the MID-3 group truly benefited by changing from 3-years of wearing single vision lenses to MiSight.
- It should be noted that this blog has been written based on the Abstract of the paper, as the full publication is not yet available. Some of the aforementioned points may be discussed further and subsequently further insight may be provided into these parameters. Furthermore, it is assumed that the authors will provide further statistical analysis of the M1D-6 group. It would be beneficial to examine the change in treatment effect observed over the 6 year period, as it provides the first long-term investigation into the efficacy of this treatment intervention.
Based on the participant numbers provided, it appears that more participants dropped out from the M1D-3 group in comparison to the M1D-6 group (10 and 6 respectively). It would be interesting to determine the cause for drop-out, specifically if it was related to lens comfort or visual performance.
Potential conflict of interest due to the author’s association with CooperVision, who are the creators of MiSight 1 day.
This study has been highly anticipated, as it provides a long-term analysis of the efficacy of the MiSight 1 day contact lens. Based on the abstract, no statistically significant difference in myopia progression was observed between the two groups. This suggests that older children still gain a substantial treatment effect from MiSight 1 day. It will be interesting to examine the 6 year findings reported in the full study, and examine the change in treatment effect over time.
Title: Myopia Progression in Children wearing Dual-Focus Contact Lenses: 6-Year Findings
Authors: Paul Chamberlain, Baskar Arumugam, Debbie Jones, Nicola Logan, Sofia Peixoto de Matos, Graeme Young, Chris Hunt, Cheryl Ngo
Purpose: To evaluate the myopia progression in children completing 6 years in dual-focus daily disposable contact lenses (MiSight1 day, omafilcon A, CooperVision, Inc.; M1D-6) contact lenses compared to a demographically matched group completing 3 years in the same product (M1D-3).
Methods: Following completion of a 3-year study (Part 1) to assess the efficacy of M1D (Chamberlain et al, OVS 2019), the control group, comprising wearers of single vision spherical daily disposable contact lenses (omafilcon A; Proclear 1 Day CooperVision Inc.), were refitted to M1D (M1D-3, 56) for a further 3 years of assessment (Part 2). The treatment group from that study continued with M1D (M1D-6, 52). The age range of both groups was 11-15 years at Part 2 baseline. Cycloplegic spherical equivalent autorefraction (SERE) and axial length (AL) were the primary endpoints measured at baseline and then subsequently at yearly intervals. Change in SERE and AL of Part 2 was compared between the groups.
Results: There was no significant difference (0.05) in fixed demographic factors between groups for Part 2 at baseline. However, the M1D-3 group commenced Part 2 with longer eyes (0.02) and more myopia (0.001) due to the treatment effect previously reported in Part 1. 92 subjects (46 M1D-6 and 46 M1D-3) completed the study, 85 of those subjects (40 M1D-6 and 45 M1D-3) attended visits in range as per protocol and were eligible for analysis. The mean change in SERE from Part 2 Baseline to the 72-month visit was -0.44D (95%CI -0.31 to -0.58) for the M1D-6 group and -0.29D (95%CI -0.17 to -0.42) for the M1D-3 group, respectively (.10). Change in AL was 0.22mm (95%CI 0.16 to 0.28) and 0.18mm (95%CI 0.13 to 0.24), respectively (.40).
Conclusion: Older children (11-15 years of age) with greater myopia and longer axial lengths (M1D-3) progressed at a similar rate over 3 years to demographically matched group of children who were treated for 6 years (M1D-6). These findings suggest that while intervening with treatment at an early age is optimal for myopia management, commencing treatment at an older age could still be beneficial in slowing the rate of myopia progression.
- Chamberlain P, Peixoto-de-Matos SC, Logan NS, Ngo C, Jones D, Young G. A 3-year Randomized Clinical Trial of MiSight Lenses for Myopia Control. Optom Vis Sci. 2019;96;556-567. [Link to Myopia Profile Review] [Link to open access paper]
- Brennan, N, et al. “Efficacy in Myopia Control”. Progress in Retinal and Eye Research, 2020. [Link to Myopia Profile Review] [Link to open access paper]
Clare Maher is a clinical optometrist in Sydney, Australia, and a second year Doctor of Medicine student, with a keen interest in research analysis and scientific writing.