Accommodation changes in MiSight dual focus lens wearers

Paper title: Changes in accommodation and behavioural performance with a contact lens for myopia management: A comparison between a dual-focus and a single-vision soft contact lens

Authors: Beatriz Redondo,¹ Jesús Vera,¹ Rubén Molina,¹ Tomás Galan,¹ Pedro Machado,¹ Raimundo Jimenez¹

1. CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, Faculty of Sciences, University of Granada, Granada, Spain.

Date: July 2022

Reference: Redondo B, Vera J, Molina R, Galán T, Machado P, Jiménez R. Changes in accommodation and behavioural performance with a contact lens for myopia management: A comparison between a dual-focus and a single-vision soft contact lens. Ophthalmic Physiol Opt. 2022 Jul;42(4):753-761. 

[Link to open access paper]

Dual-focus contact lenses for myopia management are designed to induce myopic defocus at the retinal periphery, leading to reduced myopic development and progression.¹ Some studies have reported increased accommodative lag or degraded vision quality with multifocal contact lenses, while others have found no changes in visual acuity or stereopsis despite negative visual comfort scoring from wearers.^2-12

This double-blind, crossover study compared the accommodative and behavioural performance of dual focus (MiSight 1-day) to single vision (Proclear 1-day) contact lenses during a psycho-motor vigilance task (PVT) for young adult wearers. The steady-state accommodative response and accommodative lag for 23 healthy university students (mean age of 20yrs and average myopia of up to -3.11D) was measured using WAM-5500 binocular open-field auto-refractor under steady room lighting, while they performed a 10min visual PVT task at 50cm. The response speed to the visual task was recorded. 

The students rated their sleepiness/alertness level prior to the task and how tired their eyes felt after each session. The task was repeated on different days when the participants wore either MiSight 1-day or Proclear 1-day contact lenses. They found that:

• MiSight 1-day lens wear was found to give greater lag, variability of accommodation and slower reaction times for the PVT task compared to Proclear 1-day wear with mean differences of 0.58 ± 0.81 D, 0.31 ± 0.17 D and 15.22 ± 20.93 ms, respectively.
• A time-on-task effect was seen for accommodation variability and reaction times, with longer concentration periods giving higher values. However, the lag of accommodation was not significantly different for time-on-task.
• There were no differences in self-reported alert levels before completing the PVT task. After task completion, subjective reporting of visual clarity showed average scores of 2.04 and 0.83 for MiSight 1-day and Proclear 1-day, respectively, on a severity scale of 0 to 4 (4 being most severe symptoms).

This study found that accommodative lag and variability and reaction times were increased with short-term dual focus contact lens wear. Eyecare practitioners should be aware of this when considering myopia management for patients who have lifestyles that include prolonged visual tasks and provide appropriate tailored advice.

However, this study featured young myopic adults and compared the performance of dual focus to single vision design contact lenses, whereas MiSight 1-day is frequently used to reduce myopia progression in children. They are more likely to be switching from spectacle to contact lens wear which presents other binocular vision considerations. For more information on this, see here.  Due to children have different accommodative demands, these study results may hold different clinical relevance for these patients.

This study was performed using adult participants rather than children who are expected to have different accommodative demands. Although increased accommodation response and visual task reaction times were found with MiSight wear, the results cannot be directly applied to children wearing MiSight. Further differences may be seen for adult or child wearers with abnormal binocular function.

• A decreased accommodative response in children wearing multifocal contact lenses may be due to using the near portion of the optic zone, resulting in relaxed accommodation.^7,14-16 However, others have found this is not the case and have countered that the ‘add’ power in dual focus designs provides a different response to ‘add’ powers in spectacles.²

The authors accepted that a 30min wear time of both lens types may have been too short to allow for full adaptation of the MiSight lens design and that increased wear and tolerance could influence the results found.

Further long-term studies are needed to further investigate MiSight 1-day performance for children using the lenses for different tasks at varying distances.

Title: Changes in accommodation and behavioural performance with a contact lens for myopia management: A comparison between a dual-focus and a single-vision soft contact lens

Authors: Beatriz Redondo, Jesús Vera, Rubén Molina, Tomás Galán, Pedro Machado, Raimundo Jiménez

Purpose: Dual-focus soft contact lenses for myopia management have demonstrated to be an effective strategy to reduce myopia progression. However, this optical design has been shown to alter visual quality and accommodative function. The aim of this study was to examine the accommodative and behavioural performance during the execution of a psychomotor vigilance task (PVT) while wearing dual-focus and single-vision soft contact lenses.

Methods: The steady-state accommodative response was recorded with the WAM-5500 binocular open-field autorefractor during the execution of a 10-min PVT at 50 cm either with the dual-focus (MiSight 1-day) or single-vision (Proclear 1-day) soft contact lenses, using a sample of 23 healthy young adults. Each experimental session was performed on two different days in a counterbalanced order.

Results: A greater lag of accommodation, variability of accommodation and reaction time was found while wearing dual-focus in comparison with single-vision soft contact lenses (mean differences during the 10-min PVT were 0.58 ± 0.81 D, p < 0.001; 0.31 ± 0.17 D, p < 0.001 and 15.22 ± 20.93 ms, p = 0.002, respectively). Also, a time-on-task effect was found for the variability of accommodation and reaction time (p = 0.001 and p < 0.001, respectively), observing higher values over time. However, the lag of accommodation did not change significantly as a function of time-on-task (p = 0.33).

Conclusions: Dual-focus soft contact lens wear influences the steady-state accommodative response and behavioural performance during the execution of a visual vigilance task in the short-term. Eye care practitioners should be aware of these effects when prescribing these lenses for myopia management, and provide specific recommendations according to the individual visual needs.

[Link to open access paper]