Advertisement

Dynamics of the accommodative response and facility with dual-focus soft contact lenses for myopia control

  • Jesús Vera
    Affiliations
    CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, Faculty of Sciences, University of Granada, Granada, Spain
    Search for articles by this author
  • Beatriz Redondo
    Correspondence
    Corresponding autor at: Department of Optics, University of Granada, Campus de la Fuentenueva 2, 18001 Granada, Spain.
    Affiliations
    CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, Faculty of Sciences, University of Granada, Granada, Spain
    Search for articles by this author
  • Tomás Galan
    Affiliations
    CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, Faculty of Sciences, University of Granada, Granada, Spain
    Search for articles by this author
  • Pedro Machado
    Affiliations
    CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, Faculty of Sciences, University of Granada, Granada, Spain

    Department of Computer Science, Durham University, UK
    Search for articles by this author
  • Rubén Molina
    Affiliations
    CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, Faculty of Sciences, University of Granada, Granada, Spain
    Search for articles by this author
  • George-Alex Koulieris
    Affiliations
    Department of Computer Science, Durham University, UK
    Search for articles by this author
  • Raimundo Jiménez
    Affiliations
    CLARO (Clinical and Laboratory Applications of Research in Optometry) Research Group, Department of Optics, Faculty of Sciences, University of Granada, Granada, Spain
    Search for articles by this author
Open AccessPublished:October 18, 2021DOI:https://doi.org/10.1016/j.clae.2021.101526

      Abstract

      Objective

      To assess the impact of using dual-focus soft contact lenses for myopia control on the dynamics of the accommodative response and facility.

      Methods

      24 young adult myopes were fitted with dual-focus soft contact lenses for myopia control (MiSight®) and single-vision soft contact lenses (Proclear®). The WAM-5500 open-field autorefractor was used to measure the dynamics of the accommodative response (magnitude and variability) in binocular conditions, with accommodative data being gathered from the dominant eye, at three viewing distances (500 cm, 40 cm, and 20 cm) during 90 s. Also, the binocular accommodative facility was assessed with the WAM-5500 autorefractor. All participants performed the same experimental protocol with the dual-focus (MiSight) and single-vision (Proclear) soft contact lenses, with both experimental sessions being carried in two different days and following a counterbalanced order.

      Results

      This study showed greater lags of accommodation with the MiSight than the Proclear lenses at near distances (40 cm: 1.27 ± 0.77 vs. 0.68 ± 0.37 D, corrected p-value = 0.002, Cohen-d = 0.90; and 20 cm: 1.47 ± 0.84 vs. 1.01 ± 0.52 D, corrected p-value = 0.007, Cohen-d = 0.75), whereas a higher variability of accommodation was observed with the dual-focus than the single-vision lenses at 500 cm (0.53 ± 0.11 vs. 0.23 ± 0.10 D), 40 cm (0.82 ± 0.31 vs. 0.68 ± 0.37 D), and 20 cm (1.50 ± 0.56 vs. 1.15 ± 0.39 D) (corrected p-value < 0.001 in all cases, and Cohen-ds = 0.67–2.33). Also, a worse quantitative (27.75 ± 8.79 vs. 34.29 ± 10.08 cycles per minute, p = 0.029, Cohen-d = 0.48) and qualitative (23.68 ± 7.12 vs. 28.43 ± 7.97 score, p = 0.039, Cohen-d = 0.45) performance was observed with the MiSight when compared to the Proclear lenses.

      Conclusions

      The use of dual-focus soft contact lenses for myopia control alters the dynamics of accommodative response and facility in the short-term. Although this optical design has demonstrated its effectiveness for myopia control, eye care specialists should be aware of the acute effects of these lenses on accommodation performance.

      Keywords

      1. Introduction

      Myopia is a public health issue and its prevalence has been increasing over the years. It is estimated that 5 billion people will be myopes by 2050 [
      • Holden B.A.
      • Fricke T.R.
      • Wilson D.A.
      • Jong M.
      • Naidoo K.S.
      • Sankaridurg P.
      • et al.
      Global prevalence of myopia and high myopia and temporal trends from 2000 through 2050.
      ]. Myopia can lead to pathological complications (e.g., choroidal neovascularization, myopic macular degeneration, etc.) and impairs vision‐related quality of life [
      • Vu H.T.V.
      • Keeffe J.E.
      • McCarty C.A.
      • Taylor H.R.
      Impact of unilateral and bilateral vision loss on quality of life.
      ,
      • Saw S.-M.
      • Gazzard G.
      • Shih-Yen E.C.
      • Chua W.-H.
      Myopia and associated pathological complications.
      ]. The risk factors linked to myopia progression are under scientific debate, with baseline myopia level, distance and time spent at near viewing [
      • Hsu C.-C.
      • Huang N.
      • Lin P.-Y.
      • Fang S.-Y.
      • Tsai D.-C.
      • Chen S.-Y.
      • et al.
      Risk factors for myopia progression in second-grade primary school children in Taipei: A population-based cohort study.
      ,
      • Huang P.-C.
      • Hsiao Y.-C.
      • Tsai C.-Y.
      • Tsai D.-C.
      • Chen C.-W.
      • Hsu C.-C.
      • et al.
      Protective behaviours of near work and time outdoors in myopia prevalence and progression in myopic children: A 2-year prospective population study.
      ], patientś age and race [
      • Luong T.Q.
      • Shu Y.H.
      • Modjtahedi B.S.
      • Fong D.S.
      • Choudry N.
      • Tanaka Y.
      • et al.
      Racial and ethnic differences in myopia progression in a large, diverse cohort of pediatric patients.
      ], time spent outdoors [
      • Guo Y.
      • Liu L.J.
      • Tang P.
      • Lv Y.Y.
      • Feng Y.i.
      • Xu L.
      • et al.
      Outdoor activity and myopia progression in 4-year follow-up of Chinese primary school children: The Beijing Children Eye Study.
      ], sedentary lifestyle [
      • Harrington S.C.
      • Stack J.
      • O’Dwyer V.
      Risk factors associated with myopia in schoolchildren in Ireland.
      ] and degree of parental myopia [
      • Liao C.
      • Ding X.
      • Han X.
      • Jiang Y.u.
      • Zhang J.
      • Scheetz J.
      • et al.
      Role of parental refractive status in myopia progression: 12-year annual observation from the guangzhou twin eye study.
      ] being the most prominent.
      Due to the negative public health and economic impact of myopia, there are considerable research efforts to determine the most effective intervention to slow myopia progression [
      • Brennan N.A.
      • Toubouti Y.M.
      • Cheng X.
      • Bullimore M.A.
      Efficacy in myopia control.
      ,
      • Leo S.W.
      • Adio A.
      • Fernandez A.
      • Godts D.
      • Mojon D.
      • Salchow D.J.
      • et al.
      Current approaches to myopia control.
      ,

      Ang M, Flanagan JL, Wong CW, Müller A, Davis A, Keys D, et al. Review: Myopia control strategies recommendations from the 2018 WHO/IAPB/BHVI Meeting on Myopia. Br J Ophthalmol 2020;104:1482–7.

      ]. Several pharmacological and optical strategies have been demonstrated to be helpful for this purpose [
      • Walline J.J.
      • Walker M.K.
      • Mutti D.O.
      • Jones-Jordan L.A.
      • Sinnott L.T.
      • Giannoni A.G.
      • et al.
      Effect of high add power, medium add power, or single-vision contact lenses on myopia progression in children: The BLINK randomized clinical trial.
      ,
      • Yam J.C.
      • Jiang Y.
      • Tang S.M.
      • Law A.K.P.
      • Chan J.J.
      • Wong E.
      • et al.
      Low-concentration atropine for myopia progression (LAMP) study.
      ,
      • Cho P.
      • Cheung S.-W.
      Retardation of myopia in orthokeratology (ROMIO) study: A 2-year randomized clinical trial.
      ,
      • Chamberlain P.
      • Peixoto-de-Matos S.C.
      • Logan N.S.
      • Ngo C.
      • Jones D.
      • Young G.
      A 3-year randomized clinical trial of MiSight lenses for myopia control.
      ,
      • Li S.-M.
      • Ji Y.-Z.
      • Wu S.-S.
      • Zhan S.-Y.
      • Wang B.o.
      • Liu L.-R.
      • et al.
      Multifocal versus single vision lenses intervention to slow progression of myopia in school-age children: A meta-analysis.
      ]. Among optical interventions, the use of multifocal soft-contact lenses to reduce or eliminate peripherical hyperopic defocus has gained in popularity in the last years due to its effectiveness to decelerate eye axial elongation [
      • Chamberlain P.
      • Peixoto-de-Matos S.C.
      • Logan N.S.
      • Ngo C.
      • Jones D.
      • Young G.
      A 3-year randomized clinical trial of MiSight lenses for myopia control.
      ,
      • Li S.-M.
      • Kang M.-T.
      • Wu S.-S.
      • Meng B.o.
      • Sun Y.-Y.
      • Wei S.-F.
      • et al.
      Studies using concentric ring bifocal and peripheral add multifocal contact lenses to slow myopia progression in school-aged children: a meta-analysis.
      ,
      • Remón L.
      • Pérez-Merino P.
      • Macedo-de-Araújo R.J.
      • Amorim-de-Sousa A.I.
      • González-Méijome J.M.
      Bifocal and multifocal contact lenses for presbyopia and myopia control.
      ,
      • Sankaridurg P.
      • Holden B.
      • Smith E.
      • Naduvilath T.
      • Chen X.
      • de la Jara P.L.
      • et al.
      Decrease in rate of myopia progression with a contact lens designed to reduce relative peripheral hyperopia: One-year results.
      ]. Regardless of the optical design, the contact lenses should provide an acceptable visual performance, but previous studies have shown that multifocal contact lenses affect quality of vision negatively [
      • Kang P.
      • McAlinden C.
      • Wildsoet C.F.
      Effects of multifocal soft contact lenses used to slow myopia progression on quality of vision in young adults.
      ,
      • Kollbaum P.S.
      • Jansen M.E.
      • Tan J.
      • Meyer D.M.
      • Rickert M.E.
      Vision performance with a contact lens designed to slow myopia progression.
      ,
      • Ruiz-Pomeda A.
      • Fernandes P.
      • Amorim-de-Sousa A.
      • González-Méijome J.M.
      • Prieto-Garrido F.L.
      • Pérez-Sánchez B.
      • et al.
      Light disturbance analysis in the controlled randomized clinical trial MiSight® Assessment Study Spain (MASS).
      ,
      • García‐Marqués J.V.
      • Macedo‐De‐Araújo R.J.
      • Cerviño A.
      • García‐Lázaro S.
      • McAlinden C.
      • González‐Méijome J.M.
      Comparison of short-term light disturbance, optical and visual performance outcomes between a myopia control contact lens and a single-vision contact lens.
      ]. In particular, due to the proposed association between myopia progression and ocular accommodation [
      • Cheng X.u.
      • Xu J.
      • Brennan N.A.
      Accommodation and its role in myopia progression and control with soft contact lenses.
      ,

      Price H, Allen PM, Radhakrishnan H, Calver R, Rae S, Theagarayan B, et al. The Cambridge anti-myopia study: Variables associated with myopia progression. Optom Vis Sci 2013;90:1274–83.

      ,
      • Gwiazda J.E.
      • Hyman L.
      • Norton T.T.
      • Hussein M.E.M.
      • Marsh-Tootle W.
      • Manny R.
      • et al.
      Accommodation and related risk factors associated with myopia progression and their interaction with treatment in COMET children.
      ], several authors have assessed the effects of wearing multifocal soft contact lenses for myopia control on the accommodative function [
      • Ruiz-Pomeda A.
      • Pérez-Sánchez B.
      • Cañadas P.
      • Prieto-Garrido F.L.
      • Gutiérrez-Ortega R.
      • Villa-Collar C.
      Binocular and accommodative function in the controlled randomized clinical trial MiSight® Assessment Study Spain (MASS).
      ,
      • Schmid K.
      • Gifford K.
      • Chan P.
      • Christie B.
      • Crouther S.
      • Nahuysen O.
      • et al.
      The effects of aspheric and concentric multifocal soft contact lenses on visual quality, vergence and accommodation function in young adult myopes.
      ,
      • Altoaimi B.H.
      • Kollbaum P.
      • Meyer D.
      • Bradley A.
      Experimental investigation of accommodation in eyes fit with multifocal contact lenses using a clinical auto-refractor.
      ,
      • Gong C.R.
      • Troilo D.
      • Richdale K.
      Accommodation and phoria in children wearing multifocal contact lenses.
      ,
      • Kang P.
      • Wildsoet C.F.
      Acute and short-term changes in visual function with multifocal soft contact lens wear in young adults.
      ,

      Theagarayan B, Radhakrishnan H, Allen PM, Calver RI, Rae SM, O’Leary DJ. The effect of altering spherical aberration on the static accommodative response. Ophthalmic Physiol Opt 2009;29:65–71.

      ,
      • Anstice N.S.
      • Phillips J.R.
      Effect of dual-focus soft contact lens wear on axial myopia progression in children.
      ]. Most of the available studies on myopia control have been focused on evaluating the magnitude of the accommodative response. In this regard, multifocal contact lenses wearers seem to use the positive zone of the lens during near vision to relax accommodation [
      • Kang P.
      • Wildsoet C.F.
      Acute and short-term changes in visual function with multifocal soft contact lens wear in young adults.
      ,

      Theagarayan B, Radhakrishnan H, Allen PM, Calver RI, Rae SM, O’Leary DJ. The effect of altering spherical aberration on the static accommodative response. Ophthalmic Physiol Opt 2009;29:65–71.

      ]. However, there are other measures of the accommodative function such as the variability of accommodation and accommodative facility that have been associated with myopia progression and/or have been demonstrated to be altered by the use of multifocal lenses [
      • Shibata Y.
      • Uozato H.
      • Nakayama N.
      Accommodative micro-fluctuations wearing multifocal soft contact lenses.
      ,
      • Ozkan J.
      • Fedtke C.
      • Chung J.
      • Thomas V.
      • Chandra B.R.
      Short-term adaptation of accommodative responses in myopes fitted with multifocal contact lenses.
      ,

      Lin W, Lin M, Chen Y, Chen H. Effects of near addition lenses and prisms on accommodative microfluctuations in chinese children. Optom Vis Sci 2016;93:488–96.

      ,

      Sreenivasan V, Irving EL, Bobier WR. Effect of near adds on the variability of accommodative response in myopic children. Ophthalmic Physiol Opt 2011;31:145–54.

      ], but they have not yet been investigated while wearing concentric dual-focus contact lenses for myopia control.
      Owing to the lack of scientific evidence in relation to the effects of using dual-focus soft contact lenses for myopia control on the dynamics of the accommodative response and facility, the main objectives of the present study were: (i) to determine the short-term effects of using dual-focus soft contact lenses for myopia control in comparison to single vision soft contact lenses on accommodative lag and variability, and (ii) to compare the dynamics of the accommodative facility between the dual-focus and single vision soft contact lenses, as assessed by an objective method for the qualitative and quantitative assessment of binocular accommodative facility [
      • Vera J.
      • Redondo B.
      • Molina R.
      • Koulieris G.-A.
      • Jiménez R.
      Validation of an objective method for the qualitative and quantitative assessment of binocular accommodative facility.
      ]. Based on previous studies performed with multifocal lenses, it is hypothesized that the use of dual-focus would lead to greater lags of accommodation [
      • Remón L.
      • Pérez-Merino P.
      • Macedo-de-Araújo R.J.
      • Amorim-de-Sousa A.I.
      • González-Méijome J.M.
      Bifocal and multifocal contact lenses for presbyopia and myopia control.
      ] and a reduced accommodative facility [
      • Ozkan J.
      • Fedtke C.
      • Chung J.
      • Thomas V.
      • Chandra B.R.
      Short-term adaptation of accommodative responses in myopes fitted with multifocal contact lenses.
      ], whereas no hypothesis can be formulated for the stability of the accommodative response due to the lack of studies in this regard.

      2. Methods

      2.1 Participants

      The minimum sample size required for this within-subjects experimental design was based on an a-priori calculation using the GPower 3.1 software [
      • Faul F.
      • Erdfelder E.
      • Lang A.-G.
      • Buchner A.
      G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences.
      ]. Due to the lack of previous data, an effect size of 0.25 (Coheńs d) was assumed for the dependent variables used in this study. An alpha of 0.05, power of 0.80, and level of correlation among repeated measures of 0.5 were considered. This a-priori analysis predicted that the required sample size to achieve this desired level of accuracy is 20 participants. Subsequently, 24 young myopes (75% women, average age ± standard deviation = 20.5 ± 2.0 years) were recruited to participate in this study. All participants included in this study satisfied the following inclusion criteria: (i) have a spherical equivalent ranging from −0.5 to −6.0 D, including an astigmatism error ≤ 0.75D, (ii) have a visual acuity of 0.0 logMAR or better in each eye with the optical compensation, (iii) be free of any ocular disease, (iv) have amplitude of accommodation (push-up method) within the normal range as calculated by the Hofstetter’s formula [
      • Hofstetter H.W.
      A useful age-amplitude formula.
      ], (v) have fusion, as assessed by the standard Worth-4-dot test at near (40 cm) and far (5 m) distances, and (vi) belong to the low discomfort group with the Conlon survey [

      Conlon EG, Lovegrove WJ, Chekaluk E, Pattison PE. Measuring visual discomfort. Vis Cogn 1999;6:637–63.

      ]. All the procedures followed on this study adhered to the recommendations of the Declaration of Helsinki, and permission was granted by the University of Granada Institutional Review Board (IRB approval: 1786/CEIH/2020).

      2.2 Procedure

      Participants visited the laboratory in four separate occasions on different days. During the first visit a full optometric examination was conducted, which included an objective ocular refraction and keratometry with an autokeratorefractometer (WAM-5500; Grand Seiko Co. Ltd., Hiroshima, Japan), considering the mean value from three measurements in both cases. Following this, a full monocular and binocular subjective refraction, considering an end-point criterion of maximum plus consistent with best vision using a bichromatic test, was performed. Aiming to ensure the fulfilment of the inclusion criteria (see the Participants subsection), the presence of binocular or accommodative anomalies was evaluated following the recommendations of Scheiman and Wick [
      • Scheiman M.
      • Wick B.
      Clinical management of binocular vision: heterophoric, accommodative, and eye movement disorders.
      ], as well as any ocular pathology as assessed by slit-lamp and direct ophthalmoscopy examination. At this point, dual-focus and single vision soft contact lenses (MiSight 1-day and Proclear 1-day, respectively; CooperVision, Pleasanton, CA, USA), both composed of omafilcon A material, were ordered based on the corneal measures and exact refraction compensated for vertex distance. The second session was used to evaluate that both lenses were appropriately centered, had sufficient movement, over-refraction was ≤ 0.25 D, and visual acuity was satisfactory (≤0.00 logMAR in each eye). The lens power used was the same for both lens types. Following this evaluation procedure, participants were given verbal and written instructions about the experimental conditions, which were carried out in the third and fourth sessions. These two sessions were identical except for the randomized use of the dual-focus or single vision soft contact lens. In both sessions, participants wore the lenses for at least 15 min before the assessment of accommodative dynamics in order for their ocular surface to adapt to the new contact lenses [
      • Altoaimi B.H.
      • Almutairi M.S.
      • Kollbaum P.S.
      • Bradley A.
      Accommodative behavior of young eyes wearing multifocal contact lenses.
      ]. All experimental sessions were scheduled at the same time of the day (±1 h) to minimize the influence of circadian variations, and participants were instructed to abstain from alcohol and caffeine consumption for 24 and 12 h, respectively, before visiting the laboratory.

      2.3 Assessment of the dynamics of the accommodative response and facility

      The lag and variability of the accommodative response were recorded using a binocular open-field Grand Seiko WAM-5500 autorefractor (Grand Seiko, Hiroshima, Japan), in HI-SPEED mode. This device has been validated to acquire reliable and valid accommodation data at a temporal resolution of ̴ 5 Hz and with a sensitivity of 0.01 D [

      Sheppard AL, Davies LN. Clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500. Ophthalmic Physiol Opt 2010;30:143–51.

      ,
      • Win-Hall D.M.
      • Houser J.
      • Glasser A.
      Static and dynamic measurement of accommodation using the Grand Seiko WAM-5500 autorefractor.
      ]. Recording was conducted in binocular conditions from the dominant eye, as determined by the hole-in-the-card method [
      • Momeni‐moghaddam H.
      • Goss D.A.
      • Sobhani M.
      Accommodative response under monocular and binocular conditions as a function of phoria in symptomatic and asymptomatic subjects.
      ], and while participants rested their chin and forehead on the corresponding supports. First, the monocular refractive state was measured using the WAM-5500 static mode, with measured values being further used for calculating the lag of accommodation. Then, the accommodative response was recorded continuously during 120 s while participants fixated on a stationary target (Maltese cross, Michelson contrast = 79%, base luminance = 31 cd m−2) at three different distances (500 cm, 40 cm and 20 cm). During dynamic recordings, an experienced examiner ensured that the reference marker of the WAM-5500 autorefractor was within the pupil area. A three-minute break was taken between two consecutive recordings. The data were curated following the established recommendations of removing data points of ±3 standard deviations from the mean spherical refraction, as they are considered to be blinks or recording errors [

      Tosha C, Borsting E, Ridder WH, Chase C. Accommodation response and visual discomfort. Ophthalmic Physiol Opt 2009;29:625–33.

      ]. Accommodative lag was calculated as the difference of mean accommodative response (recorded in dynamic mode) and the corresponding accommodative demand (i.e., 2.5 D at 40 cm). In order to account for the residual refractive error, and as proposed by Poltavski et al. [
      • Poltavski D.V.
      • Biberdorf D.
      • Petros T.V.
      Accommodative response and cortical activity during sustained attention.
      ], the lag of accommodation was also corrected by subtracting the baseline static refraction at far distance. For example, a subject with a mean accommodative response of 1.85 D at 40 cm, and with a residual refractive error of +0.10 D (after being optically corrected), has a near refractive state of 1.75 D. Therefore, considering that the ideal response is −2.50 D (40 cm), this subject has a lag of accommodation of 0.75 D (i.e., −1.75 – [-2.50] = 0.75 D). The measure of variability of accommodation was taken as the standard deviation of the continuous accommodative data measurements, with higher values of this parameter showing a lower stability of accommodation.
      The facility of accommodation was assessed by a recently developed objective method for the qualitative and quantitative assessment of binocular accommodative facility in free-viewing conditions [
      • Vera J.
      • Redondo B.
      • Molina R.
      • Koulieris G.-A.
      • Jiménez R.
      Validation of an objective method for the qualitative and quantitative assessment of binocular accommodative facility.
      ]. This method, known as the 2Q-AF test, combines the use of an open-field autorefractometer (WAM-5500, Grand Seiko Co. Ltd., Hiroshima, Japan) in continuous recording mode and a modified version of the Hart chart test, which includes far and near targets placed at 5 m and 40 cm, respectively. A more detailed description of the procedures required for data acquisition and analysis with the 2Q-AF test can be found in Vera et al. [
      • Vera J.
      • Redondo B.
      • Molina R.
      • Koulieris G.-A.
      • Jiménez R.
      Validation of an objective method for the qualitative and quantitative assessment of binocular accommodative facility.
      ]. Briefly, participants were asked to shift their focus of accommodation between the far and near targets when the letter became clear, and the refractive state was recorded with the autorefractometer. Data acquisition lasted for 60 s, and subsequent analyses allow us to obtain the number of cycles, percentage of incorrect cycles of accommodation and dis-accommodation, and mean magnitude of accommodative changes between the far and near targets. For the analysis of the accuracy of each accommodative change in the 2Q-AF test, a near error was considered to occur when the accommodative response for the near distance was greater (+1SD; i.e., more positive) than the baseline near measurement, whereas a far error was considered to occur accounted when the accommodative response for the far distance was smaller (−1SD; i.e., more negative) than the baseline far measurement. The mean magnitude of accommodative change was calculated as the average change between the two accommodative levels (i.e., far and near targets) in the facility test. The qualitative examination of accommodative facility was performed with the 2Q-AF score, which is calculated as described in equation (1).
      2Q-AFscore=cpm-cpm×%ofnearerrors+%offarerrors2
      (1)


      2.4 Study design and statistical analysis

      The present study followed a within-participants design to determine the short-term effects of wearing dual-focus soft contact lenses on the dynamics of the accommodative response and facility. The within-participants factors were the type of soft contact lens (MiSight, Proclear) and the target distance (500, 40, and 20 cm). The dependent variables were the lag and variability of the accommodative response, as well as the qualitative and quantitative measures of binocular accommodative facility.
      Firstly, the Shapiro–Wilk and Levene’s tests were performed to assess the normality of the data and the equality of variance, respectively (p > 0.05 in all cases). Subsequently, parametric statistics were applied for data analyses. For the dynamics of the accommodative response (lag and variability of accommodation), two separate two-way ANOVAs with the lens type (MiSight, Proclear) and the target distance (500, 40, and 20 cm) as the within-participants factors were conducted. The analysis of the binocular accommodative facilities was carried out by separate t-tests for related samples, considering the type of soft contact lenses as the only within-participants factor (MiSight, Proclear), for each of the measures derived from the binocular accommodative facility test. The level of significance was established at 0.05, and multiple comparisons were corrected with the Holm- Bonferroni procedure. Standardized effect sizes were reported by means of the partial ƞ2 (ƞ2p) for Fs and the Cohen’s d (d) for t-tests.

      3. Results

      Table 1 shows the descriptive values for the dynamic of the accommodative response (lag and variability of accommodation) and pupil size with both contact lens types.
      Table 1Descriptive (mean ± standard deviation) values of the dynamics of the accommodative response (lag and variability of accommodation) and pupil size while wearing the dual-focus and single vision soft contact lenses.
      Dual-focusSingle-vision
      Lag of accommodation (D)500 cm0.22 ± 0.670.13 ± 0.16
      40 cm1.27 ± 0.770.68 ± 0.37
      20 cm1.47 ± 0.841.01 ± 0.52
      Variability of accommodation (D)500 cm0.53 ± 0.110.23 ± 0.10
      40 cm0.82 ± 0.310.53 ± 0.19
      20 cm1.50 ± 0.561.15 ± 0.39
      Pupil size (mm)500 cm5.74 ± 0.815.51 ± 0.64
      40 cm5.40 ± 0.825.39 ± 0.74
      20 cm4.76 ± 0.904.67 ± 0.74
      There was a statistically significant effect for the lag of accommodation with the lens type (F1,23 = 9.74, p = 0.005, η2p = 0.30), target distance (F2,46 = 89.66, p < 0.001, η2p = 0.80), and the interaction “lens type × target distance” (F2,46 = 14.27, p < 0.001, η2p = 0.38). Post hoc comparison between the three targets distances revealed greater lags of accommodation at 20 cm than 40 cm (corrected p-value = 0.002, d = 0.65) and 500 cm (corrected p-value < 0.001, d = 2.63), as well as at 40 cm when compared to 500 cm (corrected p-value < 0.001, d = 1.97). The comparison between the dual-focus and single vision, contact lenses exhibited greater lags of accommodation for the dual-focus lenses at 40 cm (corrected p-value = 0.002, d = 0.90) and 20 (corrected p-value = 0.007, d = 0.75), but no differences were observed at far distance (corrected p-value = 0.510, d = 0.13) (Fig. 1, panel A).
      Figure thumbnail gr1
      Fig. 1Effects of using the dual-focus (MiSight; in red) and single vision (Proclear; in blue) soft contact lenses on the accommodative lag (panel A) and variability (panel B) at three viewing distances. * denotes a statistically significant difference between both types of soft contact lenses (corrected p-value < 0.05). Error bars show the standard error. All values are calculated across participants (n = 24). D = diopter.
      The analysis of the variability of accommodation showed statistically significant differences for the main effect of lens type (F1,23 = 37.69, p < 0.001, η2p = 0.62) and target distance (F2,46 = 145.50, p < 0.001, η2p = 0.86), but not for the interaction “lens type × target distance” (F2,46 = 0.300, p = 0.743, η2p = 0.01). Post hoc analysis between the three target distances demonstrated a lower stability of the accommodative response at 20 cm than 40 cm (corrected p-value < 0.001, d = 2.35) and 500 cm (corrected p-value < 0.001, d = 3.40), as well as at 40 cm when compared to 500 cm (corrected p-value < 0.001, d = 1.05). Pairwise comparisons between both lens types indicated a reduced stability of accommodation while wearing the dual-focus in comparison to the single vision lenses at 500 cm (corrected p-value < 0.001, d = 2.33), 40 cm (corrected p-value < 0.001, d = 1.25) and 20 cm (corrected p-value < 0.001, d = 0.67) (Fig. 1, panel B).
      Although it was beyond the aims of this study, an analysis of the pupil size while fixating at the three target distances with both lens types was carried out. Pupil size was associated with the target distance (F2,46 = 48.40, p < 0.001, η2p = 0.51), showing a smaller pupil diameter at closer distances. However, pupil size did not show statistically significant differences for the main effect of lens type (F1,23 = 1.63, p = 0.214) and the interaction “lens type × target distance” (F2,46 = 1.70, p = 0.194).
      For the binocular accommodative facility test, descriptive values and pairwise comparisons between the dual-focus and single vision soft contact lenses are shown in Table 2. The analysis of quantitative and qualitative binocular accommodative facility showed statistically significant differences for the number of cycles per minute (t23 = 2.34, p = 0.029, Coheńs d = 0.48) and the 2Q-AF score (t23 = 2.19, p = 0.039, Coheńs d = 0.45), observing a better performance with the single vision than the dual-focus soft contact lenses (Fig. 2).
      Table 2Descriptive (mean ± standard deviation) and statistical values for the parameters obtained with the binocular accommodative facility test while wearing the dual-focus and single vision soft contact lenses.
      Dual-focusSingle-visiontP-valueCohen’s d (95% CI)
      Number of cycles (cpm)27.75 ± 8.7934.29 ± 10.08−2.340.029−0.48 (−0.90 to −0.05)
      Under-accommodated (%)26.67 ± 18.383.46 ± 5.486.20<0.0011.27 (0.72 to 1.80)
      Under-relaxed (%)2.44 ± 6.6028.77 ± 19.40−7.26<0.001−1.48 (−2.06 to −0.90)
      Magnitude (D)1.62 ± 0.361.51 ± 0.391.3670.1850.28 (−0.13 to 0.68)
      Abbreviations: cpm = cycles per minute; D = diopters, CI = confidence interval.
      Figure thumbnail gr2
      Fig. 2Effects of using the dual-focus (MiSight; in red) and single vision (Proclear; in blue) soft contact lenses on the quantitative (panel A) and qualitative (panel B) measures of binocular accommodative facility. P-values and effect sizes (Coheńs d) are displayed above each comparison. The box plots represent 75th, 50th and 25th centiles. Horizontal lines and filled circles into the box represent median and mean values, respectively. The whiskers show the maximum and minimum values. All values are calculated across participants (n = 24). Note: The equation used for 2Q-AF score is reported in the text. cpm = cycles per minute.

      4. Discussion

      The present study was designed to assess the short-term effects of using dual-focus soft contact lenses for myopia control on the dynamics of the accommodative response and facility. The analysis of accommodative data evidenced greater lags of accommodation at near distances, and a lower stability of accommodation with the MiSight than the Proclear lenses at far and near distances. For the accommodative facility, wearing the MiSight lenses affected the frequency and precision of this visual ability negatively. Taken together, data from this study show that wearing dual-focus soft contact lenses significantly alters the dynamics of the accommodative response and facility in young myopes.
      Several clinical trials have demonstrated the effectiveness of the MiSight lenses in slowing changes in spherical equivalent refraction and axial length over multiple years [
      • Chamberlain P.
      • Peixoto-de-Matos S.C.
      • Logan N.S.
      • Ngo C.
      • Jones D.
      • Young G.
      A 3-year randomized clinical trial of MiSight lenses for myopia control.
      ,
      • Anstice N.S.
      • Phillips J.R.
      Effect of dual-focus soft contact lens wear on axial myopia progression in children.
      ,
      • Ruiz-Pomeda A.
      • Pérez-Sánchez B.
      • Valls I.
      • Prieto-Garrido F.L.
      • Gutiérrez-Ortega R.
      • Villa-Collar C.
      MiSight Assessment Study Spain (MASS). A 2-year randomized clinical trial.
      ]. However, in the short-term, the use of multifocal contact lenses for myopia control has been associated with a reduced accommodative response due to the use of the positive addition at near [
      • Gong C.R.
      • Troilo D.
      • Richdale K.
      Accommodation and phoria in children wearing multifocal contact lenses.
      ]. This is consistent with the findings of the current study since it was found a meaningful reduction of the accommodative magnitude at 40 and 20 cm (̴0.50D) while using the MiSight in comparison to the Proclear lenses. Remarkably, previous studies have suggested a positive association between accommodative lag and myopia progression [

      Price H, Allen PM, Radhakrishnan H, Calver R, Rae S, Theagarayan B, et al. The Cambridge anti-myopia study: Variables associated with myopia progression. Optom Vis Sci 2013;90:1274–83.

      ,
      • Gwiazda J.E.
      • Hyman L.
      • Norton T.T.
      • Hussein M.E.M.
      • Marsh-Tootle W.
      • Manny R.
      • et al.
      Accommodation and related risk factors associated with myopia progression and their interaction with treatment in COMET children.
      ]. With this study it is not possible to confirm that all participants were looking through the positive zone of the lens during the entire duration (or some moments) of the different visual tasks. Therefore, the impact of using (or not using) the added positive power of this optical design (i.e., dual-focus lenses) on the accommodative function, and its long-term effect on myopia control deserves to be explored in more detail.
      Regarding stability of accommodation, a number of studies have reported that myopes show a lower stability of accommodation than emmetropes [

      Lin W, Lin M, Chen Y, Chen H. Effects of near addition lenses and prisms on accommodative microfluctuations in chinese children. Optom Vis Sci 2016;93:488–96.

      ,

      Sreenivasan V, Irving EL, Bobier WR. Effect of near adds on the variability of accommodative response in myopic children. Ophthalmic Physiol Opt 2011;31:145–54.

      ,
      • Langaas T.
      • Riddell P.M.
      • Svarverud E.
      • Ystenaes A.E.
      • Langeggen I.
      • Bruenech J.R.
      Variability of the accommodation response in early onset myopia.
      ,
      • Harb E.
      • Thorn F.
      • Troilo D.
      Characteristics of accommodative behavior during sustained reading in emmetropes and myopes.
      ,
      • Day M.
      • Strang N.C.
      • Seidel D.
      • Gray L.S.
      • Mallen E.A.H.
      Refractive group differences in accommodation microfluctuations with changing accommodation stimulus.
      ]. In relation to the effects of using multifocal soft contact lenses on the stability of the accommodative response, Shibata and colleagues found differences in accommodative stability between multifocal and single vision soft contact lenses [
      • Shibata Y.
      • Uozato H.
      • Nakayama N.
      Accommodative micro-fluctuations wearing multifocal soft contact lenses.
      ]. The behaviour of the “steady-state” accommodation response is highly dependent on optical changes in the retinal image (e.g., spatial frequency, contrast, blur perception, etc.) [
      • Charman W.N.
      • Heron G.
      Microfluctuations in accommodation: An update on their characteristics and possible role.
      ], which may be linked to the greater levels of accommodative fluctuations observed with the dual-focus lenses for myopia control. A recent study by Garcia-Marqués et al [
      • García‐Marqués J.V.
      • Macedo‐De‐Araújo R.J.
      • Cerviño A.
      • García‐Lázaro S.
      • McAlinden C.
      • González‐Méijome J.M.
      Comparison of short-term light disturbance, optical and visual performance outcomes between a myopia control contact lens and a single-vision contact lens.
      ] found that using the MiSight lenses impairs photopic and mesopic contrast sensitivity, higher order aberrations, light disturbance and subjective perceptions of vision quality. It may also partially explain the heightened accommodative variability recorded with the dual-focus when compared to the single vision soft contact lenses as it has been demonstrated that accommodative variability is indicative of eye strain or visual fatigue [
      • Thiagarajan P.
      • Ciuffreda K.J.
      Visual fatigue and accommodative dynamics in asymptomatic individuals.
      ]. In addition, Garcia-Marques and colleagues [
      • García-Marqués J.V.
      • Macedo-de-Araújo R.
      • Lopes-Ferreira D.
      • Cerviño A.
      • García-Lázaro S.
      • González-Méijome J.M.
      Tear film stability over a myopia control contact lens compared to a monofocal design.
      ] found a slight reduction of pre-lens tear stability with the MiSight soft contact lenses, and thus, this may also contribute to the differences observed for the variability of the accommodative response. Furthermore, it is reasonable to expect that transitions between the two optical powers of the lens may induce an accommodative conflict causing the reduced stability observed with this contact lens design in far and near viewing.
      The 2Q-AF test allows to objectively acquire qualitative and quantitative measures of accommodative facility in free-viewing conditions [
      • Vera J.
      • Redondo B.
      • Molina R.
      • Koulieris G.-A.
      • Jiménez R.
      Validation of an objective method for the qualitative and quantitative assessment of binocular accommodative facility.
      ]. The ability of the visual system to stimulate and relax accommodation rapidly and accurately is of great relevance in real-word contexts (e.g., driving, sports practice, school), and has been demonstrated to be worse in myopes [
      • Pandian A.
      • Sankaridurg P.R.
      • Naduvilath T.
      • O'Leary D.
      • Sweeney D.F.
      • Rose K.
      • et al.
      Accommodative facility in eyes with and without myopia.
      ] and in eyes fitted with multifocal contact lenses [
      • Ozkan J.
      • Fedtke C.
      • Chung J.
      • Thomas V.
      • Chandra B.R.
      Short-term adaptation of accommodative responses in myopes fitted with multifocal contact lenses.
      ]. In line with this, a worse binocular accommodative facility performance was obtained with the dual-focus soft contact lenses for number of cycles/minutes and the AQ-AF metrics. Remarkably, Ozkan et al. [
      • Ozkan J.
      • Fedtke C.
      • Chung J.
      • Thomas V.
      • Chandra B.R.
      Short-term adaptation of accommodative responses in myopes fitted with multifocal contact lenses.
      ] found a significant reduction in monocular accommodative facility with multifocal soft contact lens wearing, as assessed with the ±2.00 DS lens flipper test, and they suggested that this effect may be due to the reduced visual performance achieved with multifocal designs. Therefore, it is reasonable to presume that the reduced binocular accommodative facility observed in the current study may be primarily attributed to the reduced visual performance obtained with the use of dual-focus soft contact lenses.
      This study provides evidence that dual-focus soft contact lenses for myopia management alter the dynamics of the accommodative response and facility, and although their effectiveness to slow myopia progression and axial elongation are well-documented [
      • Chamberlain P.
      • Peixoto-de-Matos S.C.
      • Logan N.S.
      • Ngo C.
      • Jones D.
      • Young G.
      A 3-year randomized clinical trial of MiSight lenses for myopia control.
      ,
      • Ruiz-Pomeda A.
      • Pérez-Sánchez B.
      • Valls I.
      • Prieto-Garrido F.L.
      • Gutiérrez-Ortega R.
      • Villa-Collar C.
      MiSight Assessment Study Spain (MASS). A 2-year randomized clinical trial.
      ], the impact of these lenses on ocular accommodation should be taken into consideration. These findings seem to be of relevance in clinical and applied settings, since the changes observed in accommodative response and facility could deteriorate visual performance in a range of daily activities as well as affect visual comfort during near work, as demonstrated in various studies [

      Tosha C, Borsting E, Ridder WH, Chase C. Accommodation response and visual discomfort. Ophthalmic Physiol Opt 2009;29:625–33.

      ,
      • Thiagarajan P.
      • Ciuffreda K.J.
      Visual fatigue and accommodative dynamics in asymptomatic individuals.
      ]. However, there are limitations that may restrict the generalizability of the current findings listed here. First, a specific type of soft contact lens for myopia control (i.e., multi-zone bifocal) was chosen, and the current results cannot be extrapolated to other optical designs. Second, the MiSight lenses contain a large central correction area of 3.36 mm surrounded by multiple refractive concentric rings of alternating distance and near powers, resulting to the retina receiving in-focus and out-of-focus images. In this case, pupil size plays an important role on visual performance with these lenses; as pupil size increases, the pupil area covered by the concentric rings increases. Future studies may consider the influence of pupil size or rings configuration of dual-focus soft contact lenses on ocular accommodation. Third, results from this study must be interpreted according to the cross-over, self-controlled design carried out in this work, and the long-term effects of using the MiSight lenses on the dynamics of the accommodative response and facility require further investigation. Fourth, changes in the dynamics of ocular accommodation have been associated with visual strain in symptomatic young subjects [

      Tosha C, Borsting E, Ridder WH, Chase C. Accommodation response and visual discomfort. Ophthalmic Physiol Opt 2009;29:625–33.

      ,
      • Thiagarajan P.
      • Ciuffreda K.J.
      Visual fatigue and accommodative dynamics in asymptomatic individuals.
      ] and during prolonged near viewing [
      • Redondo B.
      • Vera J.
      • Luque-Casado A.
      • García-Ramos A.
      • Jiménez R.
      Associations between accommodative dynamics, heart rate variability and behavioural performance during sustained attention: A test-retest study.
      ]. The external validity of these results to visually symptomatic individuals and during longer near tasks requires further investigation, since the experimental sample of the current study was formed by visually asymptomatic young adults and the near task was relatively short. Lastly, most investigations with MiSight lenses have been conducted in children, and it will be of interest to assess visual performance and comfort in this population, as children have different blur sensitivity than adults [
      • Labhishetty V.
      • Chakraborty A.
      • Bobier W.R.
      Is blur sensitivity altered in children with progressive myopia?.
      ].

      5. Conclusions

      This study found acute changes in the dynamics of accommodative response and facility as a consequence of wearing dual-focus soft contact lenses for myopia control. Greater accommodative lags and variability of accommodation were observed at near, and at far and near distances, respectively, when wearing the Mi-Sight bifocal than the single vision (i.e., Proclear) soft contact lenses. Also, the accommodative facility was quantitatively and qualitatively affected by the use of the dual-focus lenses. Eye care providers should be aware of these outcomes when prescribing these lenses for myopia management.

      Declaration of Competing Interest

      The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

      Acknowledgments

      This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. The authors thank all the participants who selflessly collaborated in this research. Funding for open access charge: Universidad de Granada / CBUA.

      References

        • Holden B.A.
        • Fricke T.R.
        • Wilson D.A.
        • Jong M.
        • Naidoo K.S.
        • Sankaridurg P.
        • et al.
        Global prevalence of myopia and high myopia and temporal trends from 2000 through 2050.
        Ophthalmology. 2016; 123: 1036-1042
        • Vu H.T.V.
        • Keeffe J.E.
        • McCarty C.A.
        • Taylor H.R.
        Impact of unilateral and bilateral vision loss on quality of life.
        Br J Ophthalmol. 2005; 89: 360-363
        • Saw S.-M.
        • Gazzard G.
        • Shih-Yen E.C.
        • Chua W.-H.
        Myopia and associated pathological complications.
        Ophthalmic Physiol Opt. 2005; 25: 381-391
        • Hsu C.-C.
        • Huang N.
        • Lin P.-Y.
        • Fang S.-Y.
        • Tsai D.-C.
        • Chen S.-Y.
        • et al.
        Risk factors for myopia progression in second-grade primary school children in Taipei: A population-based cohort study.
        Br J Ophthalmol. 2017; 101: 1611-1617
        • Huang P.-C.
        • Hsiao Y.-C.
        • Tsai C.-Y.
        • Tsai D.-C.
        • Chen C.-W.
        • Hsu C.-C.
        • et al.
        Protective behaviours of near work and time outdoors in myopia prevalence and progression in myopic children: A 2-year prospective population study.
        Br J Ophthalmol. 2020; 104: 956-961
        • Luong T.Q.
        • Shu Y.H.
        • Modjtahedi B.S.
        • Fong D.S.
        • Choudry N.
        • Tanaka Y.
        • et al.
        Racial and ethnic differences in myopia progression in a large, diverse cohort of pediatric patients.
        Investig Ophthalmol Vis Sci. 2020; 61: 1-8
        • Guo Y.
        • Liu L.J.
        • Tang P.
        • Lv Y.Y.
        • Feng Y.i.
        • Xu L.
        • et al.
        Outdoor activity and myopia progression in 4-year follow-up of Chinese primary school children: The Beijing Children Eye Study.
        PLoS ONE. 2017; 12: 1-4
        • Harrington S.C.
        • Stack J.
        • O’Dwyer V.
        Risk factors associated with myopia in schoolchildren in Ireland.
        Br J Ophthalmol. 2019; 103: 1803-1809
        • Liao C.
        • Ding X.
        • Han X.
        • Jiang Y.u.
        • Zhang J.
        • Scheetz J.
        • et al.
        Role of parental refractive status in myopia progression: 12-year annual observation from the guangzhou twin eye study.
        Investig Ophthalmol Vis Sci. 2019; 60: 3499-3506
        • Brennan N.A.
        • Toubouti Y.M.
        • Cheng X.
        • Bullimore M.A.
        Efficacy in myopia control.
        Prog Retin Eye Res. 2020; 27100923
        • Leo S.W.
        • Adio A.
        • Fernandez A.
        • Godts D.
        • Mojon D.
        • Salchow D.J.
        • et al.
        Current approaches to myopia control.
        Curr Opin Ophthalmol. 2017; 28: 267-275
      1. Ang M, Flanagan JL, Wong CW, Müller A, Davis A, Keys D, et al. Review: Myopia control strategies recommendations from the 2018 WHO/IAPB/BHVI Meeting on Myopia. Br J Ophthalmol 2020;104:1482–7.

        • Walline J.J.
        • Walker M.K.
        • Mutti D.O.
        • Jones-Jordan L.A.
        • Sinnott L.T.
        • Giannoni A.G.
        • et al.
        Effect of high add power, medium add power, or single-vision contact lenses on myopia progression in children: The BLINK randomized clinical trial.
        JAMA. 2020; 324: 571https://doi.org/10.1001/jama.2020.10834
        • Yam J.C.
        • Jiang Y.
        • Tang S.M.
        • Law A.K.P.
        • Chan J.J.
        • Wong E.
        • et al.
        Low-concentration atropine for myopia progression (LAMP) study.
        Ophthalmology. 2019; 126: 113-124
        • Cho P.
        • Cheung S.-W.
        Retardation of myopia in orthokeratology (ROMIO) study: A 2-year randomized clinical trial.
        Investig Ophthalmol Vis Sci. 2012; 53: 7077https://doi.org/10.1167/iovs.12-10565
        • Chamberlain P.
        • Peixoto-de-Matos S.C.
        • Logan N.S.
        • 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
        • Li S.-M.
        • Ji Y.-Z.
        • Wu S.-S.
        • Zhan S.-Y.
        • Wang B.o.
        • Liu L.-R.
        • et al.
        Multifocal versus single vision lenses intervention to slow progression of myopia in school-age children: A meta-analysis.
        Surv Ophthalmol. 2011; 56: 451-460
        • Li S.-M.
        • Kang M.-T.
        • Wu S.-S.
        • Meng B.o.
        • Sun Y.-Y.
        • Wei S.-F.
        • et al.
        Studies using concentric ring bifocal and peripheral add multifocal contact lenses to slow myopia progression in school-aged children: a meta-analysis.
        Ophthalmic Physiol Opt. 2017; 37: 51-59
        • Remón L.
        • Pérez-Merino P.
        • Macedo-de-Araújo R.J.
        • Amorim-de-Sousa A.I.
        • González-Méijome J.M.
        Bifocal and multifocal contact lenses for presbyopia and myopia control.
        J Ophthalmol. 2020; 2020: 1-18
        • Sankaridurg P.
        • Holden B.
        • Smith E.
        • Naduvilath T.
        • Chen X.
        • de la Jara P.L.
        • et al.
        Decrease in rate of myopia progression with a contact lens designed to reduce relative peripheral hyperopia: One-year results.
        Investig Ophthalmol Vis Sci. 2011; 52: 9362https://doi.org/10.1167/iovs.11-7260
        • Kang P.
        • McAlinden C.
        • Wildsoet C.F.
        Effects of multifocal soft contact lenses used to slow myopia progression on quality of vision in young adults.
        Acta Ophthalmol. 2017; 95: e43-e53
        • Kollbaum P.S.
        • Jansen M.E.
        • Tan J.
        • Meyer D.M.
        • Rickert M.E.
        Vision performance with a contact lens designed to slow myopia progression.
        Optom Vis Sci. 2013; 90: 205-214
        • Ruiz-Pomeda A.
        • Fernandes P.
        • Amorim-de-Sousa A.
        • González-Méijome J.M.
        • Prieto-Garrido F.L.
        • Pérez-Sánchez B.
        • et al.
        Light disturbance analysis in the controlled randomized clinical trial MiSight® Assessment Study Spain (MASS).
        Contact Lens Anterior Eye. 2019; 42: 200-205
        • García‐Marqués J.V.
        • Macedo‐De‐Araújo R.J.
        • Cerviño A.
        • García‐Lázaro S.
        • McAlinden C.
        • González‐Méijome J.M.
        Comparison of short-term light disturbance, optical and visual performance outcomes between a myopia control contact lens and a single-vision contact lens.
        Ophthalmic Physiol Opt. 2020; 40: 718-727
        • Cheng X.u.
        • Xu J.
        • Brennan N.A.
        Accommodation and its role in myopia progression and control with soft contact lenses.
        Ophthalmic Physiol Opt. 2019; 39: 162-171
      2. Price H, Allen PM, Radhakrishnan H, Calver R, Rae S, Theagarayan B, et al. The Cambridge anti-myopia study: Variables associated with myopia progression. Optom Vis Sci 2013;90:1274–83.

        • Gwiazda J.E.
        • Hyman L.
        • Norton T.T.
        • Hussein M.E.M.
        • Marsh-Tootle W.
        • Manny R.
        • et al.
        Accommodation and related risk factors associated with myopia progression and their interaction with treatment in COMET children.
        Investig Ophthalmol Vis Sci. 2004; 45: 2143https://doi.org/10.1167/iovs.03-1306
        • Ruiz-Pomeda A.
        • Pérez-Sánchez B.
        • Cañadas P.
        • Prieto-Garrido F.L.
        • Gutiérrez-Ortega R.
        • Villa-Collar C.
        Binocular and accommodative function in the controlled randomized clinical trial MiSight® Assessment Study Spain (MASS).
        Graefe’s Arch Clin Exp Ophthalmol. 2019; 257: 207-215
        • Schmid K.
        • Gifford K.
        • Chan P.
        • Christie B.
        • Crouther S.
        • Nahuysen O.
        • et al.
        The effects of aspheric and concentric multifocal soft contact lenses on visual quality, vergence and accommodation function in young adult myopes.
        Invest Ophthalmol Vis Sci. 2019; 60: 3893
        • Altoaimi B.H.
        • Kollbaum P.
        • Meyer D.
        • Bradley A.
        Experimental investigation of accommodation in eyes fit with multifocal contact lenses using a clinical auto-refractor.
        Ophthalmic Physiol Opt. 2018; 38: 152-163
        • Gong C.R.
        • Troilo D.
        • Richdale K.
        Accommodation and phoria in children wearing multifocal contact lenses.
        Optom Vis Sci. 2017; 94: 353-360
        • Kang P.
        • Wildsoet C.F.
        Acute and short-term changes in visual function with multifocal soft contact lens wear in young adults.
        Contact Lens Anterior Eye. 2016; 39: 133-140
      3. Theagarayan B, Radhakrishnan H, Allen PM, Calver RI, Rae SM, O’Leary DJ. The effect of altering spherical aberration on the static accommodative response. Ophthalmic Physiol Opt 2009;29:65–71.

        • Anstice N.S.
        • Phillips J.R.
        Effect of dual-focus soft contact lens wear on axial myopia progression in children.
        Ophthalmology. 2011; 118: 1152-1161
        • Shibata Y.
        • Uozato H.
        • Nakayama N.
        Accommodative micro-fluctuations wearing multifocal soft contact lenses.
        Invest Ophthalmol Vis Sci. 2012; 53: 4725
        • Ozkan J.
        • Fedtke C.
        • Chung J.
        • Thomas V.
        • Chandra B.R.
        Short-term adaptation of accommodative responses in myopes fitted with multifocal contact lenses.
        Eye Contact Lens. 2018; 44: S30-S37
      4. Lin W, Lin M, Chen Y, Chen H. Effects of near addition lenses and prisms on accommodative microfluctuations in chinese children. Optom Vis Sci 2016;93:488–96.

      5. Sreenivasan V, Irving EL, Bobier WR. Effect of near adds on the variability of accommodative response in myopic children. Ophthalmic Physiol Opt 2011;31:145–54.

        • Vera J.
        • Redondo B.
        • Molina R.
        • Koulieris G.-A.
        • Jiménez R.
        Validation of an objective method for the qualitative and quantitative assessment of binocular accommodative facility.
        Curr Eye Res. 2020; 45: 636-644
        • Faul F.
        • Erdfelder E.
        • Lang A.-G.
        • Buchner A.
        G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences.
        Behav Res Methods. 2007; 39: 175-191
        • Hofstetter H.W.
        A useful age-amplitude formula.
        Am J Optom Arch Am Acad Optom. 1950; 38: 42-45
      6. Conlon EG, Lovegrove WJ, Chekaluk E, Pattison PE. Measuring visual discomfort. Vis Cogn 1999;6:637–63.

        • Scheiman M.
        • Wick B.
        Clinical management of binocular vision: heterophoric, accommodative, and eye movement disorders.
        Lippincott Williams & Wilkins, Philadelphia2008
        • Altoaimi B.H.
        • Almutairi M.S.
        • Kollbaum P.S.
        • Bradley A.
        Accommodative behavior of young eyes wearing multifocal contact lenses.
        Optom Vis Sci. 2018; 95: 416-427
      7. Sheppard AL, Davies LN. Clinical evaluation of the Grand Seiko Auto Ref/Keratometer WAM-5500. Ophthalmic Physiol Opt 2010;30:143–51.

        • Win-Hall D.M.
        • Houser J.
        • Glasser A.
        Static and dynamic measurement of accommodation using the Grand Seiko WAM-5500 autorefractor.
        Optom Vis Sci. 2010; 87
        • Momeni‐moghaddam H.
        • Goss D.A.
        • Sobhani M.
        Accommodative response under monocular and binocular conditions as a function of phoria in symptomatic and asymptomatic subjects.
        Clin Exp Optom. 2014; 97: 36-42
      8. Tosha C, Borsting E, Ridder WH, Chase C. Accommodation response and visual discomfort. Ophthalmic Physiol Opt 2009;29:625–33.

        • Poltavski D.V.
        • Biberdorf D.
        • Petros T.V.
        Accommodative response and cortical activity during sustained attention.
        Vision Res. 2012; 63: 1-8
        • Ruiz-Pomeda A.
        • Pérez-Sánchez B.
        • Valls I.
        • Prieto-Garrido F.L.
        • Gutiérrez-Ortega R.
        • Villa-Collar C.
        MiSight Assessment Study Spain (MASS). A 2-year randomized clinical trial.
        Graefe’s Arch Clin Exp Ophthalmol. 2018; 256: 1011-1021
        • Langaas T.
        • Riddell P.M.
        • Svarverud E.
        • Ystenaes A.E.
        • Langeggen I.
        • Bruenech J.R.
        Variability of the accommodation response in early onset myopia.
        Optom Vis Sci. 2008; 85: 37-48
        • Harb E.
        • Thorn F.
        • Troilo D.
        Characteristics of accommodative behavior during sustained reading in emmetropes and myopes.
        Vision Res. 2006; 46: 2581-2592
        • Day M.
        • Strang N.C.
        • Seidel D.
        • Gray L.S.
        • Mallen E.A.H.
        Refractive group differences in accommodation microfluctuations with changing accommodation stimulus.
        Ophthalmic Physiol Opt. 2006; 26: 88-96
        • Charman W.N.
        • Heron G.
        Microfluctuations in accommodation: An update on their characteristics and possible role.
        Ophthalmic Physiol Opt. 2015; 35: 476-499
        • Thiagarajan P.
        • Ciuffreda K.J.
        Visual fatigue and accommodative dynamics in asymptomatic individuals.
        Optom Vis Sci. 2013; 90: 57-65
        • García-Marqués J.V.
        • Macedo-de-Araújo R.
        • Lopes-Ferreira D.
        • Cerviño A.
        • García-Lázaro S.
        • González-Méijome J.M.
        Tear film stability over a myopia control contact lens compared to a monofocal design.
        Clin Exp Optom. 2021; 00: 1-7
        • Pandian A.
        • Sankaridurg P.R.
        • Naduvilath T.
        • O'Leary D.
        • Sweeney D.F.
        • Rose K.
        • et al.
        Accommodative facility in eyes with and without myopia.
        Investig Ophthalmol Vis Sci. 2006; 47: 4725https://doi.org/10.1167/iovs.05-1078
        • Redondo B.
        • Vera J.
        • Luque-Casado A.
        • García-Ramos A.
        • Jiménez R.
        Associations between accommodative dynamics, heart rate variability and behavioural performance during sustained attention: A test-retest study.
        Vision Res. 2019; 163: 24-32
        • Labhishetty V.
        • Chakraborty A.
        • Bobier W.R.
        Is blur sensitivity altered in children with progressive myopia?.
        Vision Res. 2019; 154: 142-153