Overminus Lens Therapy for Children 3 to 10 Years of Age With Intermittent Exotropia: A Randomized Clinical Trial

Key Points

Question  Does overminus lens therapy improve distance control in children with intermittent exotropia?

Findings  This randomized clinical trial found that mean distance exotropia control was significantly better among 386 children aged 3 to 10 years treated with overminus spectacles vs nonoverminus spectacles for 12 months; however, after weaning off overminus spectacles, there was little or no difference in distance control between groups. Myopic shift was approximately one-third diopter greater in the overminus than in the nonoverminus group.

Meaning  Overminus lens therapy improved distance exotropia control in children 3 to 10 years of age but was associated with greater myopic shift, and the improved control did not persist after overminus treatment was discontinued.

Importance  This is the first large-scale randomized clinical trial evaluating the effectiveness and safety of overminus spectacle therapy for treatment of intermittent exotropia (IXT).

Objective  To evaluate the effectiveness of overminus spectacles to improve distance IXT control.

Design, Setting, and Participants  This randomized clinical trial conducted at 56 clinical sites between January 2017 and January 2019 associated with the Pediatric Eye Disease Investigator Group enrolled 386 children aged 3 to 10 years with IXT, a mean distance control score of 2 or worse, and a refractive error between 1.00 and −6.00 diopters (D). Data analysis was performed from February to December 2020.

Interventions  Participants were randomly assigned to overminus spectacle therapy (−2.50 D for 12 months, then −1.25 D for 3 months, followed by nonoverminus spectacles for 3 months) or to nonoverminus spectacle use.

Main Outcomes and Measures  Primary and secondary outcomes were the mean distance IXT control scores of participants examined after 12 months of treatment (primary outcome) and at 18 months (3 months after treatment ended) assessed by an examiner masked to treatment group. Change in refractive error from baseline to 12 months was compared between groups. Analyses were performed using the intention-to-treat population.

Results  The mean (SD) age of 196 participants randomized to overminus therapy and 190 participants randomized to nonoverminus treatment was 6.3 (2.1) years, and 226 (59%) were female. Mean distance control at 12 months was better in participants treated with overminus spectacles than with nonoverminus spectacles (1.8 vs 2.8 points; adjusted difference, −0.8; 95% CI, −1.0 to −0.5; P < .001). At 18 months, there was little or no difference in mean distance control between overminus and nonoverminus groups (2.4 vs 2.7 points; adjusted difference, −0.2; 95% CI, −0.5 to 0.04; P = .09). Myopic shift from baseline to 12 months was greater in the overminus than the nonoverminus group (−0.42 D vs −0.04 D; adjusted difference, −0.37 D; 95% CI, −0.49 to −0.26 D; P < .001), with 33 of 189 children (17%) in the overminus group vs 2 of 169 (1%) in the nonoverminus group having a shift higher than 1.00 D.

Conclusions and Relevance  Children 3 to 10 years of age had improved distance exotropia control when assessed wearing overminus spectacles after 12 months of overminus treatment; however, this treatment was associated with increased myopic shift. The beneficial effect of overminus lens therapy on distance exotropia control was not maintained after treatment was tapered off for 3 months and children were examined 3 months later.

Trial Registration  ClinicalTrials.gov Identifier: NCT02807350

Overminus lens therapy is a nonsurgical treatment option for childhood intermittent exotropia (IXT), in which an optical correction with more minus power than the cycloplegic refractive error is worn.^1,2 Overminus lenses are typically used as a temporary treatment to improve control of IXT in young children before considering surgery^3-7 or orthoptics.^4,7 Some authors have reported success in maintaining good control and binocular function after gradually decreasing the strength of the overminus lenses over time and ultimately discontinuing the overminus lenses.^5,6

Most previous studies of overminus spectacles are retrospective case series or small prospective studies without comparison groups.^3-10 However, a previous pilot randomized clinical trial found that, compared with observation, short-term (8-week) distance IXT control improved while wearing overminus spectacles of −2.50 diopters (D).¹¹

Quiz Ref IDThe present randomized clinical trial of children 3 to 10 years of age evaluated the effectiveness of overminus lens therapy for improving distance IXT control while wearing overminus lenses, after 12 months of overminus treatment, and 3 months after the overminus lens treatment was tapered off. In addition, potential adverse effects on refractive error and symptoms associated with use of overminus spectacles were monitored.

The study was conducted according to the tenets of the Declaration of Helsinki¹² by the Pediatric Eye Disease Investigator Group at 56 academic- and community-based clinical sites. An independent data and safety monitoring committee provided oversight. The study was designed in 2016 and is listed on ClinicalTrials.gov.¹³ This study followed the Consolidated Standards of Reporting Trials (CONSORT) reporting guideline. The full trial protocol is available in Supplement 1. The protocol and informed consent forms, compliant with the Health Insurance Portability and Accountability Act, were approved by institutional review boards for each site, and a parent or guardian (hereafter referred to as parent) of each study participant gave written informed consent. Study participants received $50 compensation per visit.

Eligible children were 3 to younger than 11 years of age with cycloplegic spherical equivalent (SE) refractive error between −6.00 D and 1.00 D inclusive, and IXT of moderate or poor control and meeting specified magnitude criteria (Box). Additional eligibility criteria are shown in the Box.

Box Section Ref ID

Testing at enrollment was performed through the participant’s habitual correction. Control of the exodeviation was measured at distance (6 m) and near (0.3 m) using the IXT Office Control Score,¹⁴ which ranges from 0 (phoria) to 5 (constant exotropia) (eTable 1 in Supplement 2). Control levels 3 to 5 were assigned based on the duration of manifest exotropia during a 30-second period before any dissociation. If no exotropia was observed during this period, control levels 0 to 2 were assigned based on the longest time to reestablishing fusion following 3 consecutive 10-second periods of dissociation. Control was measured at the beginning, middle, and end (3 tests total) of a 20- to 40-minute office examination, and the mean level was used.^15-17 The following tests were performed sequentially by the same study-certified examiner (pediatric optometrist, pediatric ophthalmologist, or certified orthoptist): first control assessment; stereoacuity using the Randot Preschool Stereoacuity test (Stereo Optical Co, Inc) at 40 cm; second control assessment; cover-uncover test; prism and alternate cover test (PACT) at distance and near; PACT retesting at distance with −2.00 D lenses over the habitual correction to assess the ratio of accommodative convergence to accommodation; and third control assessment. Distance visual acuity was assessed using an optotype method. Cycloplegic refraction was performed within 2 months prior to enrollment; cycloplegic autorefraction was also performed at clinical sites that had an autorefractor.

In addition, each child completed an IXT Symptom Survey¹⁸ to assess IXT-related symptoms, and the parent completed a 7-item Spectacles Symptom Survey to assess issues related to overminus spectacle wear (eg, headache, eyestrain, and looking over glasses). Health-related quality of life was assessed using the Intermittent Exotropia Questionnaire (IXTQ)^19,20 for each child (separate version for 5- to 7-year-old children vs ≥8-year-old children) and parent. Participants were randomly assigned 1:1 using a permuted block design stratified by site and distance control (2 to <3, 3 to <4, 4 to 5 points), to either overminus or nonoverminus spectacles.

Participants assigned to the overminus group were prescribed spectacles with −2.50 D added to the spherical power of the cycloplegic refraction to be worn for 12 months. Participants were then weaned by wearing −1.25 D overminus lenses for 3 months, before discontinuing overminus lenses and wearing nonoverminus spectacles until the 18-month visit.

Participants assigned to the nonoverminus group were prescribed spectacles that fully corrected astigmatism, anisometropia, and myopia based on the cycloplegic refraction to be worn for 18 months. For participants with SE hyperopia, the sphere power that resulted in a SE plano lens were prescribed for the less hyperopic eye, with symmetrical reduction in the fellow eye.

To keep participants masked, the spectacle prescription was sealed in an envelope, and spectacle lenses were changed in both treatment groups at 12 and 15 months. In both treatment groups, spectacles were worn full time. No other IXT treatments were allowed unless the participant met motor or stereo deterioration criteria (eTable 2 in Supplement 2), after which treatment was at investigator discretion.

On observing greater myopic shift in the overminus group, the data and safety monitoring committee discontinued overminus lens treatment in November 2019. When implemented in December 2019, the study had completed 345 (89%) 12-month visits, 303 (78%) 15-month visits, and 250 (65%) 18-month visits.

Follow-up visits occurred at 6, 12 (primary outcome), 15, and 18 months (secondary outcome) (±1 month) after randomization. Telephone calls were completed at 1, 3, 9, 13, and 16 months after randomization to verify receipt of new spectacles and to maintain rapport with the family.

At each follow-up visit, the spectacle prescription was verified, and adherence with spectacle wear was rated based on parental report of the percentage of wear time during waking hours: excellent (>75%), good (51%-75%), fair (26%-50%), or poor (≤25%). Participants and parents then completed the symptom and IXTQ surveys. With participants wearing their current (ie, study) spectacles, an examiner masked to treatment group measured near stereoacuity, performed 3 IXT control assessments (at the beginning, middle, and end of the masked examination) at distance and near, the cover-uncover test, and the PACT at distance and near, in the order described for enrollment. If near stereoacuity had worsened by 2 or more octaves from baseline or to nil, it was retested (eTable 2 in Supplement 2). If stereoacuity remained decreased, it was then retested on a subsequent day (within a month) to confirm or refute meeting stereo deterioration criteria. A cycloplegic refraction was performed by an unmasked examiner at 12-month visits; cycloplegic autorefraction was also performed when available at the clinical site.

Assuming an SD of 1.8 points in the IXT control score based on a prior pilot study by members of our group,¹¹ 2-sided α = .05, a power of 90%, and up to 10% loss to follow-up, a sample size of 384 (192 per group) was needed to detect a difference in mean 12-month and mean 18-month distance control scores (overminus − nonoverminus), assuming the true mean difference was −0.65 points or larger.

The primary analysis was an intention-to-treat treatment group comparison of mean distance control score after 12 months of treatment using analysis of covariance (ANCOVA) adjusting for baseline values of distance control, age, refractive error, and distance (eAppendix in Supplement 2). Multiple imputation using the Markov chain Monte Carlo model²¹ with baseline adjustment factors (distance control, age, refractive error, and distance PACT) and follow-up control scores was performed to impute missing control scores for each treatment group separately in the primary analysis (eAppendix in Supplement 2). Sensitivity analyses were conducted to evaluate the effects of missing data handling on study results (eAppendix in Supplement 2). The primary analysis was repeated within baseline subgroups in exploratory analyses.

Using the same ANCOVA model as the primary analysis, the mean 18-month distance control scores were compared between treatment groups. As a sensitivity analysis, the 18-month analysis was repeated, limited to 292 participants who completed the full treatment and weaning period (ie, had completed the 15-month visit) prior to early discontinuation of overminus by the data and safety monitoring committee.

Additional secondary outcomes related to the exodeviation (control and magnitude) and stereoacuity were compared between treatment groups using ANCOVA models adjusted for the baseline level of the outcome. The cumulative probabilities of deterioration by 12 and by 18 months were calculated by treatment group using Cox proportional hazards models.

As a safety outcome, mean 12-month SE cycloplegic refractive error was compared between treatment groups using ANCOVA adjusting for baseline refractive error and age. The risk ratio between treatment groups for the proportion of participants with an increase in SE myopia from baseline to 12 months of higher than 1.00 D was also calculated using the Farrington-Manning score method.²²

Item responses for the IXT Child Symptom Survey¹⁸ and the Parent Spectacle/Symptom Survey and median scores for the child and parent IXTQ²⁰ components were tabulated. The IXTQ domain scores were compared between treatment groups at 12 and 18 months using the Wilcoxon rank sum test.

We adjusted P values to control the false discovery rate²³ at 5% separately for IXTQ domain scores and for all other secondary outcomes (eAppendix in Supplement 2). All analyses were conducted using SAS, version 9.4 (SAS Institute Inc).

Between January 2017 and January 2019, 386 children were enrolled at 56 sites, with 196 children assigned to overminus lens therapy and 190 children to nonoverminus lens treatment. Baseline demographic characteristics (age: mean [SD], 6.3 [2.1] years; range, 3.0-11.0 vs 3.0-10.7 years; sex: 226 [59%] female; 112 [57%] vs 114 [60%] girls) and clinical characteristics appeared similar in the treatment groups (Table 1).

The overall completion rate was 93% for the 12-month follow-up and 86% for the 18-month follow-up. Twelve-month follow-up was incomplete for 7 of 196 participants (4%) in the overminus group and 21 of 190 participants (11%) in the nonoverminus group (Figure). Eighteen-month follow-up was incomplete for 20 of 196 participants (10%) in the overminus group and 35 of 190 participants (18%) in the nonoverminus group (Figure). Of 331 participants who completed the 18-month visit, only 292 (88%) completed the full treatment and weaning protocol. Clinical characteristics of those with incomplete vs complete 18-month follow-up are provided in eTable 3 in Supplement 2. All examiners assessing outcome measures were masked to the participants’ assigned treatment.

Spectacle wear adherence was reported as excellent for 149 children in the overminus group and 144 children in the nonoverminus group, which was 76% of each treatment group, at 12 months (eTable 4 in Supplement 2). Two participants in each treatment group received nonstudy IXT treatment before 12 months.

Quiz Ref IDThe overminus group, wearing their study spectacles, had better mean (SD) distance control after 12 months of treatment (1.8 [1.3] points) compared with the nonoverminus group (2.8 [1.5] points) (adjusted treatment group difference, −0.8 points; 95% CI, −1.0 to −0.5 points; P < .001) (Table 2; eFigure 1 in Supplement 2). Mean distance control scores were imputed for 34 participants (10 in overminus and 24 in nonoverminus). Several sensitivity analyses that were completed (eAppendix in Supplement 2) yielded results similar to the primary analysis.

Treatment group differences in secondary outcomes favored the overminus group, except for little or no difference in stereoacuity (Table 2). In exploratory analyses, a 12-month treatment effect favoring the overminus group was observed across all baseline subgroups, including baseline distance control, baseline SE refractive error, age, accommodative convergence to accommodation ratio, sex, and race/ethnicity (eFigure 2 in Supplement 2).

At the 18-month visit (3 months after overminus spectacles were discontinued), the mean distance control was 2.4 points for 176 participants in the overminus group vs 2.7 points in 155 participants in the nonoverminus group (adjusted treatment group difference, −0.2; 95% CI, −0.5 to 0.04; P = .09) (Table 2). Mean distance control scores were imputed for 68 participants (29 in overminus and 39 in nonoverminus). There were little or no differences between treatment groups for secondary outcomes at 18 months (Table 2).

Based on cycloplegic retinoscopy, the overminus group showed a greater SE myopic change than the nonoverminus group (−0.42 vs −0.04 D; adjusted treatment group difference, −0.37 D; 95% CI, −0.49 to −0.26 D; P < .001). Of 189 children in the overminus group, 33 (17%) had higher than 1.00 D of myopic shift compared with 2 of 169 children (1%) in the nonoverminus group, with a risk ratio of 14.8 (95% CI, 4.0-182.6) (Table 3). The increased myopic shift in the overminus vs nonoverminus groups occurred particularly in children who already had myopia compared with children with emmetropia or hyperopia at baseline (Table 3). Cycloplegic autorefraction data were available in one-third of participants and yielded results similar to the cycloplegic retinoscopy findings (Table 3). The overminus and nonoverminus groups appeared similar in development of esotropia (4 of 189 [2%] vs 4 of 169 [2%]), 2 or more line decrease in visual acuity (12 of 189 [6%] vs 10 of 169 [6%]), and amblyopia treatment prescribed by 12 months (2 of 189 [1%] vs (1 of 169 [1%]).

At 12 months, the frequency of most IXT symptoms appeared relatively similar between treatment groups, except more children in the overminus group (71 of 189 [38%]) reported that their eyes hurt sometimes or always compared with the nonoverminus group (37 of 169 [22%]) (eTable 5 in Supplement 2). Parent-reported symptom and spectacle data are given in eTable 6 in Supplement 2.

At 12 months, health-related quality of life was scored as 78.8 (overminus) vs 71.5 (nonoverminus) on the psychosocial subscale, 75.1 (overminus) vs 70.6 (nonoverminus) on the function subscale, and 68.7 (overminus) vs 54.2 (nonoverminus) on the surgery subscale of the parent IXTQ; little or no difference was observed in the child IXTQ scores between treatment groups. At 18 months, there were no treatment group differences in the child or the parent IXTQ scores (eTable 7 in Supplement 2).

Quiz Ref IDThis randomized clinical trial of 3- to 10-year-old children with IXT found that the overminus group had a better distance IXT control score while wearing overminus spectacles at 1 year after study treatment compared with the nonoverminus group, but this treatment effect did not persist after the participants were weaned off the overminus spectacles. In addition, the overminus group had a greater myopic shift at 12 months compared with the nonoverminus group, with the risk of higher than 1.00 D of myopic shift during this period being approximately 15 times that of the nonoverminus group.

Improved IXT control while wearing overminus spectables has been reported in a previous pilot randomized clinical trial,¹¹ 2 prospective observational studies without comparison groups,^6,9 and retrospective case series reports.^3,5 Aside from the pilot randomized clinical trial, the present trial differs from the previous studies in study design, strength of overminus power used, treatment duration, and outcome measures, making comparisons across studies difficult. The 0.8-point mean improvement in the distance IXT control score while wearing overminus spectacles at 12 months in the present study is nearly identical to the 0.75-point mean improvement found in the previous 8-week pilot randomized clinical trial that evaluated the same overminus lens power.¹¹ Taken together, these 2 studies suggest that there is a relatively fast response to overminus spectacles after treatment initiation, which then appears to remain stable over time, given that IXT control was essentially the same at 8 weeks, 6 months, and 12 months. Exploratory analyses found a 12-month treatment benefit of overminus lens therapy across age, refractive error, distance IXT control, and the ratio of accommodative convergence to accommodation.

In the present study, the treatment benefit observed at 12 months did not persist after the participants were weaned off their overminus lenses. Two retrospective studies^5,6 have reported differing success rates of improved control after discontinuation of overminus spectacle therapy; however, neither study had a control group. In the present study, a modest improvement in distance control occurred from baseline to 18 months in both treatment groups, indicating the importance of a control group to differentiate whether the improved control was due to overminus treatment or to other factors, such as spontaneous improvement unrelated to the overminus lens treatment or regression to the mean. In clinical practice, overminus lenses are typically weaned over an extended period, either by gradually reducing the overminus lens power^5,6 (eg, 0.50-D steps)⁶ or wear time,²⁴ given satisfactory control with the reduced overminus lens power in a clinical examination. In the present study, a 50% reduction in overminus lens power was prescribed for only 3 months, after which the lenses were discontinued regardless of exotropia control. In contrast to a more gradual and dynamic weaning procedure, the present study used a standardized, fixed overminus lens reduction of short duration that did not require numerous control assessments to improve feasibility for a multicenter clinical trial. A different weaning method may have facilitated retention of the treatment effect observed at 12 months.

Previous retrospective studies^5,25-27 that evaluated refractive error changes with overminus spectacles concluded that overminus spectacle therapy was associated with no more myopic shift than what would normally be expected for the age group being treated. In the present study, we found a greater myopic shift associated with overminus lens treatment, particularly in children with myopia already present at baseline. The treatment group difference in myopic change found in the present study supports the suggestion that the overminus lens treatment was causative. The increased risk of myopic shift should be weighed against the potential benefits of overminus spectacles when discussing this treatment with parents.

Quiz Ref IDThis study has limitations. Although the 12-month follow-up completion rate was 93%, 3 times as many participants were lost to follow-up in the nonoverminus (21 [11%]) vs the overminus group (7 [4%]). This differential loss to follow-up was accounted for in the primary analysis by imputing missing 12-month data separately for each treatment group. Only 292 of 331 participants (88%) with 18-month data had completed the full treatment and weaning protocol; however, a sensitivity analysis limited to these participants yielded similar results. Another limitation is that refractive error was assessed with cycloplegic retinoscopy by an unmasked examiner, and cycloplegic autorefraction data were available for only 33% of participants. At present, it is unknown whether the myopic shift is permanent or temporary. We are collecting data on change in refractive error and axial length at 24 and 36 months in the extension phase of the present study.

In conclusion, after 12 months of overminus lens wear, children 3 to 10 years of age showed improved distance IXT control when assessed with their overminus spectacles; however, the treatment was associated with an increased risk of myopic shift. Because the beneficial treatment effect did not persist after the participants were weaned off overminus spectacles for 3 months and examined 3 months later, the utility of using our overminus lens treatment protocol as a primary therapy for IXT may be limited. When considering overminus lenses as a potential treatment to temporarily improve IXT control, clinicians and parents should weigh the potential benefit of better eye alignment against the increased risk of myopic shift, particularly in children who already have myopia.

Accepted for Publication: January 12, 2021.

Published Online: March 4, 2021. doi:10.1001/jamaophthalmol.2021.0082

Corresponding Author: Angela M. Chen, OD, MS, Jaeb Center for Health Research, 15310 Amberly Dr, Ste 350, Tampa, FL 33647 (pedig@jaeb.org).

Author Contributions: Ms Hercinovic had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Chen, Erzurum, Chandler, Melia, Suh, Kong, Kraker, Holmes, Cotter.

Acquisition, analysis, or interpretation of data: Chen, Chandler, Hercinovic, Melia, Bhatt, Vricella, Erickson, Miller, Marsh, Bodack, Martinson, Titelbaum, Gray, Holtorf, Kong, Kraker, Rahmani, Shah, Holmes, Cotter.

Drafting of the manuscript: Chen, Erzurum, Chandler, Hercinovic, Titelbaum, Kraker.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Chandler, Hercinovic, Melia, Kraker, Holmes.

Obtained funding: Kraker, Holmes, Cotter.

Administrative, technical, or material support: Bhatt, Vricella, Miller, Gray, Kong, Kraker, Rahmani, Holmes, Cotter.

Supervision: Chen, Erzurum, Chandler, Melia, Suh, Miller, Marsh, Kraker, Holmes, Cotter.

Conflict of Interest Disclosures: None reported.

Funding/Support: Research reported in this publication was supported by grants EY011751, EY023198, EY018810, and EY024333 from the National Eye Institute of the National Institutes of Health.

Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Members of the Pediatric Eye Disease Investigator Group (PEDIG):

Clinical Sites: Sites are listed in order by number of participants enrolled (in parentheses). Personnel are listed as (I) for Investigator, (C) for Coordinator, or (E) for Examiner.

Department of Ophthalmology, Texas Children’s Hospital, Houston, TX (22): Evelyn A. Paysse (I); Amit R. Bhatt (I); Kelsie B. Morrison (I); Irene T. Tung (I); Kimberly G. Yen (I); Gihan Romany (C). Children’s Hospital & Medical Center, Omaha, NE (22): Donny W. Suh (I); Whitney R. Brown (I); Rachel M. Smith (I); Carolyn Chamberlain (C); Samiksha Fouzdar Jain (E); Linda A. Morgan (E). Ticho Eye Associates, Chicago Ridge, IL (17): Benjamin H. Ticho (I); Megan Allen (I); Birva K. Shah (I); Deborah A. Clausius (C); Micaela N. Quebbemann (E). Virginia Pediatric Eye Center, Virginia Beach, VA (17): Eric Crouch (I); Earl R. Crouch, Jr (I); Stacy R. Martinson (I); Gaylord G. Ventura (C). Cincinnati Children’s Hospital, Cincinnati, OH (16): Michael E. Gray (I); Melissa L. Rice (I); Neil Vallabh (C); Shemeka Rochelle Forte (E); Miqua Lynn Stewart (E). Children's Mercy Hospitals and Clinics, Kansas City, MO (15): Amy L. Waters (I); Justin D. Marsh (I); Rebecca J. Dent (C); Adriana Marie Ferreira (E); Jennifer N. Qayum (E); Christina M. Twardowski (E). Greater Baltimore Medical Center, Baltimore, MD (14): Mary Louise Z. Collins (I); Allison A. Jensen (I); Maureen A. Flanagan (C); Saman Bhatti (E); Cheryl L. McCarus (E); Tiffany Talia Tolbert (E). Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL (14): Sudhi P. Kurup (I); Rebecca B. Mets-Halgrimson (I); Bahram Rahmani (I); Magdalena Stec (I); Janice B. Zeid (I); Hantamalala Ralay Ranaivo (C); Erika A. De Leon (E); Anthony Jeffrey Klauer (E); Vivian Tzanetakos (E); Laura McCoy Vrablec (E). College of Optometry, State University of New York, New York, NY (14): Marilyn Vricella (I); Monica Joao (C); Shelby Leach (E); Rochelle Mozlin (E); Daniella Rutner (E); Erica L. Schulman-Ellis (E). University Eye Center at Ketchum Health, Anaheim, CA (13): Susan A. Cotter (I); Angela M. Chen (I); Silvia Han (I); Catherine L. Heyman (I); Reena A. Patel (I); Dashaini V. Retnasothie (I); Sue M. Parker (C); Desireh Akhamzadeh (E); Kristine Huang (E). Houston Eye Associates, The Woodlands, TX (13): Aaron M. Miller (I); Jorie L. Jackson (C); Monsey L. Alexander (E); Angela C. Dillon (E). Boston Medical Center, Boston, MA (11): Stephen P. Christiansen (I); Kara C. LaMattina (I); Jenna R. Titelbaum (I); Marissa G. Fiorello (C); Merit Gorgy (C); Nina Tamashunas (C); Natalie Sadlak (C); Wanjiku G. Githere (C); Jiwoo Kim (C); Abigail R. Goldberg (C); Mary A. Tresvalles (C); Kelly M. Castle (E); Jennifer E. Lambert (E). Nemours Children’s Clinic, Jacksonville, FL (10): John W. Erickson (I); Amy Thrift (C); Charlotte Ann Louise Reaser (E). UPMC Children’s Eye Center of Children’s Hospital of Pittsburgh, Pittsburgh, PA (10): Ken K. Nischal (I); Craig A. Luchansky (I); Ellen B. Mitchell (I); Sara Otaibi (I); Matthew S. Pihlblad (I); Lauren M. Runkel (C); Kaajal Nanda (E); Katherine Sanchez (E); Christin L. Sylvester (E). Arkansas Children’s Hospital/University of Arkansas Medical Sciences, Little Rock, AR (9): Paul H. Phillips (I); Adriana Paula Grigorian (I); Hannah L. Holtorf (I); Beth Colon (C); Shawn L. Cupit (E). Southern College of Optometry, Memphis, TN (9): Marie I. Bodack (I); Randy C. Brafford (C); Alicia A. Groce (E); Marc B. Taub (E). Illinois College of Optometry (ICO), Chicago, IL (8): Yi Pang (I); Megan Allen (I); Huizi Yin (I); Elyse Nylin (C). Texas Tech University Health Science Center, Lubbock, TX (8): Lingkun Kong (I); Misty Rae Sisneros (C); Connie J. Crossnoe (E). Salus University/Pennsylvania College of Optometry, Philadelphia, PA (8): Erin C. Jenewein (I); Stanley W. Hatch (I); Jenny Myung (I); Ruth Y. Shoge (I); Karen E. Pollack (C); Mitchell M. Scheiman (E). UAB School of Optometry, Birmingham, Alabama (7): Tamara S. Oechslin (I); Marcela Frazier (I); Katherine K. Weise (I); Jenifer Montejo (C); Margaret Kathleen Bailey (E); Kristine B. Hopkins (E); Candice I. Turner (E). Concord Ophthalmologic Associates, Concord, NH (7): Christie L. Morse (I); Caroline C. Fang (E); Jacqueline Kathryn Gavin (E). Pediatric Ophthalmology, PC, Grand Rapids, Michigan (7): Patrick J. Droste (I); Robert J. Peters (I); Jan Hilbrands (C); Kylie L. Smith (E). Mayo Clinic, Rochester, MN (7): Erick D. Bothun (I); Brian G. Mohney (I); Tomohiko Yamada (I); Suzanne M. Wernimont (C); Adam M. Hauglid (E); Lindsay D. Klaehn (E); Andrea M. Kramer (E); Laura Lepor (E); Sarah R. Mickow (E). Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, KY (6): Christi M. Willen (I); Julia L. Stevens (I); Yvonne R. James (C); Michele Reg (C); John Mark Franklin (E). CHU-Sainte-Justine, Montreal (6): Rosanne Superstein (I); Maryse Thibeault (C); Afifa Argoubi (E); Charlotte Riguidel (E); Alexandra Rodrigues (E). Dean A. McGee Eye Institute, University of Oklahoma, Oklahoma City, OK (6): R. Michael Siatkowski (I); Janine E. Collinge (I); Maria E. Lim (I); Tammy Yanovitch (I); Alisha N. Brewer (C); Laurie Parrott (E); Lauren M. Pendarvis (E). Stanford University, Palo Alto, CA (6): Scott R. Lambert (I); Deborah Alcorn (I); Euna B. Koo (I); Naz Jehangir (C); Kristina Liu (C); Tawna L. Roberts (E); Amanda M. Yonkers (E). Wilmer Institute, Baltimore, MD (5): Michael X. Repka (I); Courtney Kraus (I); Xiaonong Liu (C); Alex Christoff (E). Indiana University School of Optometry, Bloomington, IN (5): Don W. Lyon (I); Katie S. Connolly (I); Kristy M. Dunlap (C). Pediatric Eye Specialists, Chattanooga, TN (5): Rachel L. Brown (I); Edward A. Peterson (I). Duke University Eye Center, Durham, NC (5): Nathan L. Cheung (I); Sarah K. Jones (C); Sandra Holgado (E); Rachel N. Loud (E); Ivonne J. Rodriguez (E). Helen DeVos Children’s Hospital Pediatric Ophthalmology, Grand Rapids, MI (5): Brooke E. Geddie (I); Julie A. Conley (I); Elisabeth T. Wolinski (C); Sonia Manuchian (E); Katie L. Patterson (E); Samantha K. Rosen (E). Children’s Eye Care PC, West Bloomfield, MI (5): Lisa Bohra (I); Elena M. Gianfermi (I); Susan Nicole Perzyk (C); Stephen Michael Burwell (E); Mary Ann DeYoung-Smith (E); Lauren Marozas (E); Judy Lynn Petrunak (E); Martha Mary Wright (E). Wolfe Eye Clinic, West Des Moines, IA (5): Derek P. Bitner (I); Alexis C. Hahn (C); Lisa M. Fergus (E). University of Florida, Gainesville, FL (4): Swati Agarwal-Sinha (I); Casey J. Beal (I); Shannon Hampton (C); Kati M. Ostvig (E). Midwestern University Therapy Institute, Glendale, AZ (4): Alicia E. Feis (I); Caitlin C. Miller (I); Kelly D. Varney (I); Tracy A. Bland (C); Christina A. Esposito (E); Matthew K. Roe (E). Riley Hospital for Children, Indianapolis, IN (4): Kathryn M. Haider (I); Charline S. Boente (I); Heather A. Smith (I); Michele E. Whitaker (C). The Emory Eye Center, Atlanta, GA (3): Jason H. Peragallo (I); Amy K. Hutchinson (I); Phoebe D. Lenhart (I); Natalie C. Weil (I); Judy L. Brower (C); Alex Frederick Lyons (E); Shane P. Mulvihill (E); Marla J. Shainberg (E). St Luke’s Children’s Ophthalmology, Boise, ID (3): Katherine A. Lee (I); Laurie A. Cartwright (C); Kevin R. Gertsch (E). The Ohio State University, Columbus, OH (3): Marjean T. Kulp (I); Jennifer S. Fogt (I); Steven T. Manning (I); Ann M. Morrison (I); Maureen D. Plaumann (I); Erica Rose Shelton (I); Freda Dallas (C); Nancy E. Stevens (C); Michelle J. Buckland (E); Andrew J. Toole (E). Nova Southeastern University College of Optometry, The Eye Institute, Ft Lauderdale, FL (3): Cristina L. Law (I); Deborah M. Amster (I); Amar Sayani (I); Felicia Jean Timmermann (C); Michael J. Au (E); Katherine E. Green (E); Jacqueline Rodena (E); Yin C. Tea (E); Julie A. Tyler (E). University of Houston College of Optometry, Houston, TX (3): Ruth E. Manny (I); Heather A. Anderson (I); Debra C. Currie (I); Muriel M. Martinez (I). Eye Care Associates, Inc, Poland, OH (3): S. Ayse Erzurum (I); Alysa Christiansen (C); Zainab Dinani (E). Western University College of Optometry, Pomona, CA (3): Ida Chung (I); Kimberly R. Walker (I); Jennifer Baker (C); Elaine C. Ramos (E). Akron Children’s Hospital, Akron, OH (2): Casandra S. Solis (I); Ana Juric (C); Isabel Ricker (C); Tawna Roberts (E); Palak B. Wall (E). The Eye Specialist Center, LLC, Munster, IN (2): Birva K. Shah (I); Benjamin H. Ticho (E). UCSF Department of Ophthalmology, San Francisco, CA (2): Alejandra de Alba Campomanes (I); Yizhuo Bastea-Forte (C); Laura Kate Chalkley (E); Karen Cooper (E). Pediatric Eye Associates, Wilmette, IL (2): Lisa C. Verderber (I); Deborah R. Fishman (I); Roberta A. Forde (C). Tufts Medical Center, Boston, MA (1): Catherine S. Choi (I); Sara Galinko (C); Shelley J. Klein (E). Alberta Children's Hospital, Calgary (1): William F. Astle (I); Emi Nicole Sanders (C); Catriona I. Kerr (E); Heather N. Sandusky (E); Shannon L. Steeves (E). Medical University of South Carolina, Storm Eye Institute, Charleston, SC (1): Edward W. Cheeseman (I); Mae M. Peterseim (I); Carol U. Bradham (C). Gundersen Health System, La Crosse, WI (1): David L. Nash (I); Sara R. Meyers (C); Fabiana Berns (E). Loma Linda University Eye Institute, Loma Linda, CA (1): Timothy W. Winter (I); Marcia M. Easterly (C); Rosalynn Nguyen-Strongin (E). University of Minnesota–Minnesota Lions Children’s Eye Clinic, Minneapolis, MN (1): Sara J. Downes (I); Sasha Strul (I); Ann M. Holleschau (C); Laura M. May (E); Kim S. Merrill (E); Anna I. Schweigert (E). OHSU Casey Eye Institute, Portland, OR (1): Allison I. Summers (I); Paula K. Rauch (C); Grant Andrew Casey (E); Kevin M. Woodruff (E). Pacific University College of Optometry, Portland, OR (1): Paula A. Luke (I); Richard London (I); Jayne L. Silver (C); Ryan C. Bulson (E); James J. Kundart (E).

PEDIG Coordinating Center–Tampa, FL: Raymond T. Kraker, Roy W. Beck, Gillaine Alvarez, Darrell S. Austin, Nicole M. Boyle, Danielle L. Chandler, Patricia L. Connelly, Courtney L. Conner, Trevano W. Dean, Quayleen Donahue, Brooke P. Fimbel, Robert J. Henderson, Amra Hercinovic, James E. Hoepner, Joseph D. Kaplon, Zhuokai Li, B. Michele Melia, Julianne L. Robinson, Jennifer A. Shah, David O. Toro, Rui Wu.

Intermittent Exotropia Study 5 Planning Committee: Angela M. Chen (Co-Chair), S. Ayse Erzurum (Co-Chair), Jonathan M. Holmes, Danielle L. Chandler, David A. Leske, Raymond T. Kraker, Roy W. Beck, Eileen E. Birch, Michael X. Repka, David K. Wallace, Allison A. Jensen, Reena A. Patel, B. Michele Melia, Courtney L. Conner.

PEDIG Executive Committee: Susan A. Cotter (Co-chair), Jonathan M. Holmes (Co-chair), Roy W. Beck, Eileen E. Birch, Angela M. Chen (2017-18), Stephen P. Christiansen (2018-present), Laura B. Enyedi (2014-16), S. Ayse Erzurum (2016-present), Donald F. Everett, Sharon F. Freedman (2016-18), William V. Good (2017-19), Raymond T. Kraker, Katherine A. Lee (2014-16), Richard London (2018-present), Vivian M. Manh (2016-18), Ruth E. Manny (2017-19), David G. Morrison (2018-19), Stacy L. Pineles (2019-present), Hantamalala Ralay Ranaivo (2019-present), Michael X. Repka, Scott T. Ruark (2018-19), Bonita R. Schweinler (2016-18), Jayne L. Silver (2014-16), Allison I. Summers (2019-present), Lisa C. Verderber (2015-17), David K. Wallace, Katherine K. Weise (2019-present).

Strabismus Steering Committee: Amit Bhatt (2019-present), Eileen E. Birch, Danielle L. Chandler, Angela M. Chen (2016-present), Patricia Cobb (2019), Susan A. Cotter, Eric R. Crouch (2015-18), Trevano W. Dean (2015-18), Sean P. Donahue (2010-present), S. Ayse Erzurum (2016-present), Michael E. Gray (2017), Kammi B. Gunton (2016-17), Sarah R. Hatt, Jonathan M. Holmes, Erin C. Jenewein (2018), Raymond T. Kraker, Courtney Kraus (2018), Sudhi P. Kurup (2019), Elizabeth L. Lazar (2014-18), Zhuokai Li (2020-present), Justin D. Marsh (2018-19), Michele Melia, David G. Morrison (2018-present), Yi Pang (2017-18), Sue M. Parker (2017-18), Reena Patel (2016-17), Michael X. Repka, Dashaini V. Retnasothie (2019), Tawna L. Roberts (2017), Allyson Sala (2016-17), Elyse Nylin (2019-present), Allison I. Summers (2018-present), Marilyn Vricella (2019-present), Tomohiko Yamada (2015-16).

National Eye Institute: Donald F. Everett.

Data and Safety Monitoring Committee: Marie Diener-West (chair), John D. Baker, Barry Davis, Dale L. Phelps, Stephen W. Poff, Richard A. Saunders, Lawrence Tychsen.

Meeting Presentation: This paper was presented at the Annual Meeting of the American Academy of Optometry; October 7, 2020; virtual meeting; and the Annual Meeting of the Association for Pediatric Ophthalmology and Strabismus; April 13, 2021; virtual meeting.

Data Sharing Statement: See Supplement 3.