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Purpose: This study aimed to identify baseline factors associated with greater myopia progression and axial elongation in children with myopia., Methods: This study performed a post hoc analysis of data from a 30-month randomized trial of atropine 0.01% versus placebo in children 5 to <13 years old with baseline spherical equivalent refractive error (SER) of -1.00 to -6.00 D, astigmatism of ≤1.50 D, and anisometropia of <1.00 D SER. Data from atropine 0.01% and placebo groups were pooled given outcomes were similar. Baseline factors of age, SER, axial length, race, sex, parental myopia, and iris color were evaluated for association with changes in SER and with changes in axial length at 30 months (24 months on treatment and then 6 months off) using backward model selection., Results: Among 187 randomized participants, 175 (94%) completed 30 months of follow-up. The mean change in SER was greater among younger children (-0.19 D per 1 year younger; 95% confidence interval [CI], -0.25 to -0.14 D; p<0.001) and children with higher myopia (-0.14 D per 1 D more myopia at baseline; 95% CI, -0.23 to -0.05 D; p=0.002). The mean change in axial length was also greater among younger children (0.13 mm per 1 year younger; 95% CI, 0.10 to 0.15 mm; p<0.001) and children with higher baseline myopia (0.04 mm per 1 D more myopia; 95% CI, 0.002 to 0.08; p=0.04)., Conclusions: Younger children with higher myopia had greater myopic progression and axial elongation over 30 months than older children with lower myopia. Developing effective treatments to slow the faster myopic progression in younger children should be a target of further research., Competing Interests: Conflict of Interest Disclosure: None of the authors have reported a financial conflict of interest. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding organizations., (Copyright © 2024 American Academy of Optometry.)

Significance: Exposure to long-wavelength light has been proposed as a potential intervention to slow myopia progression in children. This article provides an evidence-based review of the safety and myopia control efficacy of red light and discusses the potential mechanisms by which red light may work to slow childhood myopia progression.The spectral composition of the ambient light in the visual environment has powerful effects on eye growth and refractive development. Studies in mammalian and primate animal models (macaque monkeys and tree shrews) have shown that daily exposure to long-wavelength (red or amber) light promotes slower eye growth and hyperopia development and inhibits myopia induced by form deprivation or minus lens wear. Consistent with these results, several recent randomized controlled clinical trials in Chinese children have demonstrated that exposure to red light for 3 minutes twice a day significantly reduces myopia progression and axial elongation. These findings have collectively provided strong evidence for the potential of using red light as a myopia control intervention in clinical practice. However, several questions remain unanswered. In this article, we review the current evidence on the safety and efficacy of red light as a myopia control intervention, describe potential mechanisms, and discuss some key unresolved issues that require consideration before red light can be broadly translated into myopia control in children., Competing Interests: Conflict of Interest Disclosure: None of the authors have reported a financial conflict of interest. There was no sponsorship for the submitted review., (Copyright © 2023 American Academy of Optometry.)

Importance: Controlling myopia progression is of interest worldwide. Low-dose atropine eye drops have slowed progression in children in East Asia., Objective: To compare atropine, 0.01%, eye drops with placebo for slowing myopia progression in US children., Design, Setting, and Participants: This was a randomized placebo-controlled, double-masked, clinical trial conducted from June 2018 to September 2022. Children aged 5 to 12 years were recruited from 12 community- and institution-based practices in the US. Participating children had low to moderate bilateral myopia (-1.00 diopters [D] to -6.00 D spherical equivalent refractive error [SER])., Intervention: Eligible children were randomly assigned 2:1 to 1 eye drop of atropine, 0.01%, nightly or 1 drop of placebo. Treatment was for 24 months followed by 6 months of observation., Main Outcome and Measures: Automated cycloplegic refraction was performed by masked examiners. The primary outcome was change in SER (mean of both eyes) from baseline to 24 months (receiving treatment); other outcomes included change in SER from baseline to 30 months (not receiving treatment) and change in axial length at both time points. Differences were calculated as atropine minus placebo., Results: A total of 187 children (mean [SD] age, 10.1 [1.8] years; age range, 5.1-12.9 years; 101 female [54%]; 34 Black [18%], 20 East Asian [11%], 30 Hispanic or Latino [16%], 11 multiracial [6%], 6 West/South Asian [3%], 86 White [46%]) were included in the study. A total of 125 children (67%) received atropine, 0.01%, and 62 children (33%) received placebo. Follow-up was completed at 24 months by 119 of 125 children (95%) in the atropine group and 58 of 62 children (94%) in the placebo group. At 30 months, follow-up was completed by 118 of 125 children (94%) in the atropine group and 57 of 62 children (92%) in the placebo group. At the 24-month primary outcome visit, the adjusted mean (95% CI) change in SER from baseline was -0.82 (-0.96 to -0.68) D and -0.80 (-0.98 to -0.62) D in the atropine and placebo groups, respectively (adjusted difference = -0.02 D; 95% CI, -0.19 to +0.15 D; P = .83). At 30 months (6 months not receiving treatment), the adjusted difference in mean SER change from baseline was -0.04 D (95% CI, -0.25 to +0.17 D). Adjusted mean (95% CI) changes in axial length from baseline to 24 months were 0.44 (0.39-0.50) mm and 0.45 (0.37-0.52) mm in the atropine and placebo groups, respectively (adjusted difference = -0.002 mm; 95% CI, -0.106 to 0.102 mm). Adjusted difference in mean axial elongation from baseline to 30 months was +0.009 mm (95% CI, -0.115 to 0.134 mm)., Conclusions and Relevance: In this randomized clinical trial of school-aged children in the US with low to moderate myopia, atropine, 0.01%, eye drops administered nightly when compared with placebo did not slow myopia progression or axial elongation. These results do not support use of atropine, 0.01%, eye drops to slow myopia progression or axial elongation in US children., Trial Registration: ClinicalTrials.gov Identifier: NCT03334253.

Significance: Pre-participation physical evaluation and its vision screenings have been the mainstay of medical clearance for competitive play for decades. The ability of screening to address athlete's sports-specific vision needs is unknown., Methods: Fifty-eight intercollegiate football players consented to participate in a comprehensive, sports-specific eye examination in addition to the standard pre-participation vision screening. Sensitivity, specificity, and positive and negative predictive values were determined for screening's ability to detect athletes whose vision might improve with correction, athletes who had significant ocular findings that impact safety, and either of the two conditions together. The effect no recent eye examination added to pre-participation vision screening results was evaluated for change in screening yield. Descriptive statistics of the cohort and associations with no recent comprehensive eye examination were generated., Results: The pre-participation vision screening was able to identify three athletes not meeting visual acuity requirements for medical clearance to play without a comprehensive assessment. A failed screening was poorly able to identify athletes who might benefit from improved acuity (sensitivity, 9.1%; specificity, 100%), have sports-specific significant ocular findings (sensitivity, 10.5%; specificity, 97.3%), or have either together (sensitivity, 7.5%; specificity, 100%). Sixty percent (33/55) of athletes reported never having a comprehensive examination or one within the last 10 years. Fifty-eight percent (34/58) had improved best-corrected visual acuity after comprehensive examination, and 81% (47/58) had improved acuity or a sports-specific significant finding., Conclusions: The pre-participation vision screening was largely able to identify athletes meeting the minimum visual acuity requirement for athlete clearance. It poorly identified those who might benefit from improved vision with refractive correction and those in whom sport-specific significant eye findings were noted. Comprehensive eye care had a clear benefit for the majority of athletes tested. This benefit needs to be balanced with the potential added costs and time constraints to players and athletic department staff., Competing Interests: Conflict of Interest Disclosure: None of the authors have reported a conflict of interest., (Copyright © 2021 American Academy of Optometry.)

Objective: The main objective of this study was to assess whether objective vestibular, oculomotor, and balance functions were impaired in children with a current diagnosis of concussion with vestibular and/or ocular symptoms., Setting: Data were collected in a vestibular/ocular clinical laboratory. Patient participants were recruited from a concussion clinic in a children's hospital., Participants: Thirty-three children aged 8 to 17 years with a current diagnosis of concussion and vestibular and/or ocular symptoms and 30 children without concussion., Design: Cross-sectional single-visit study., Main Outcome Measures: Eye-tracking rotary chair oculomotor and vestibular measures, vestibular evoked potentials, and static posturography., Results: There were no statistically significant differences on any clinical measure between children with concussion and children without concussion. Younger children without concussion performed significantly worse on several rotary chair and balance measures compared with older children without concussion., Conclusions: No vestibular, oculomotor, or balance measures were significantly different between children with concussion and children without concussion, suggesting these measures may not be useful in the evaluation of a child with concussion and vestibular and/or oculomotor symptoms. Future research should investigate age effects and other vestibular and oculomotor tests to identify objective findings that better relate to vestibular and/or ocular symptoms in children with concussion., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Significance: Football helmet visors are popular among players and may increase safety. However, they may also be costly or impractical, or impair the evaluation of head and neck injury. Determining an objective list of vision-related clinical conditions may help meet risk-benefit ratios while increasing access to care to athletes with special needs., Purpose: The purpose of this study was to determine an objective list of vision-related conditions that may benefit from clear and tinted football helmet visor use in athletes., Methods: After comprehensive dilated eye examinations on 58 Division I collegiate football players at the University of Alabama at Birmingham between February 2017 and June 2018, an expert panel in vision care, sports medicine, and football equipment convened to determine vision-related conditions most important for clear or tinted football helmet visor use., Results: In August 2018, the list drafted by the expert vision and sports medical panel in which a clear football helmet visor might be justified included conditions associated with retinal detachment and unilateral or binocular vision loss as well as high refractive error, refractive surgery, corneal compromise, and other conditions, which would necessitate additional eye protection. Of the 58 players examined, 3 (5%) were determined to have eye conditions that would require a clear visor as deemed by the expert panel, and 3 (5%) were determined to have eye conditions for which a clear visor was recommended. No players met indications for a tinted visor including congenital eye conditions that limit useful vision in daylight or bright-light environments, acquired conditions that may increase light sensitivity, and light-induced systemic conditions., Conclusions: This objective list of eye and vision-related systemic conditions is intended to mitigate the risk of long-term eye damage and/or vision deprivation. Clear and especially tinted football helmet visors require the sports medicine team to evaluate factors that will maximize the vision, head, and neck health of the athlete while increasing accessibility to sports for individuals with unique abilities., Competing Interests: Conflict of Interest Disclosure: None of the authors have reported a financial conflict of interest., (Copyright © 2021 American Academy of Optometry.)

Background: Aside from racial and socioeconomic disparities in computerized neurocognitive testing and symptomology, there is a scarcity of research representing more diverse populations on other widely used tests for concussion, including vestibular and visual assessment., Aim: The aim of the study was to investigate if racial and socioeconomic differences exist on baseline vestibular/ocular motor screening (VOMS) and King-Devick (K-D) test performance in high school student-athletes., Methods: A total of 670 participants (66.1% White, 33.9% Black) with a mean age of 15.43±1.2 years were administered a baseline VOMS, average Near Point of Convergence (NPC) distance, and K-D test. The exposure variables included race (White or Black) and socioeconomic status (SES), defined as free and reduced lunch status (FRL or No-FRL). FRL status was determined by each participant's school SES. The outcome variables consisted of baseline VOMS item symptom provocation scores, average NPC distance, and K-D baseline time. A series of Mann-Whitney U tests were performed for K-D baseline time, NPC distance, and VOMS items with FRL status or race as a between-subject factor. Two multivariable linear regressions were run to assess the association of (1) K-D baseline times using FRL, race, sex, and corrected vision as variables in the model and (2) average NPC distance using FRL, race, sex, and corrected vision as variables in the model., Results: When adjusting for multiple comparisons, FRL athletes had slower (worse) K-D times ( P <0.001) than non-FRL athletes. Black athletes had significantly lower mean NPC distance compared to White athletes at baseline ( P =0.02) and FRL status athletes reported a significantly greater (worse) mean symptom provocation following the visual motion sensitivity item on the VOMS ( P =0.02); however, these findings were no longer significant following adjustments for multiple comparisons. No differences were noted for any remaining VOMS items. The first model explained 3.9% of the total variance of K-D baseline times, whereas the second model was not significant., Conclusions: Racial and SES differences existed on average NPC distance and the K-D test at baseline. Possible explanations for group differences may be neurobiological, anatomical, and/or disparity in nature. With a higher probability of undiagnosed and uncorrected vision impairment, vestibular dysfunction, and saccadic eye tracking deficits likely to be more apparent as a consequence of poverty or health inequities, it is important that healthcare providers, especially those that diagnose and treat concussions, understand that performance on the VOMS and K-D tests at baseline may be subject to sociodemographic factors of SES and race., Relevance for Patients: To provide the most culturally competent care, clinicians should consider sociodemographic variables of race and SES as social determinants of health worthy of attention on objective and subjective measures of baseline concussion assessment., Competing Interests: The authorship team has no conflicts of interest to report for this work., (Copyright: © Whioce Publishing Pte. Ltd.)

Purpose: To compare visual acuity (VA) and binocularity outcomes in moderately hyperopic children with normal VA and binocularity assigned to glasses versus observation., Design: Prospective randomized clinical trial (RCT)., Methods: One hundred nineteen 3- to 5-year-old children with hyperopia between +3.00D and +6.00D spherical equivalent were randomly assigned to glasses versus observation (with glasses prescribed if deteriorated for subnormal distance VA or near stereoacuity, or manifest strabismus). Follow-up occurred every 6 months. At 3 years, the treatment strategy was classified as "failed" if any of the following were met, both with and without correction: subnormal distance VA or stereoacuity; manifest strabismus; or strabismus surgery during follow-up., Results: Of 84 (71%) children who completed the primary outcome examination, failure occurred in five (12%; 95% confidence interval [CI]: 4%-26%) of 41 assigned to glasses and four (9%; 95% CI: 3%-22%) of 43 assigned to observation (difference = 3%; 95% CI: -12%-18%; P = .72). Deterioration prior to 3 years (requiring glasses per protocol) occurred in 29% (95% CI: 19%-43%) assigned to glasses and 27% (95% CI: 17%-42%) assigned to observation., Conclusions: In an RCT comparing glasses to observation for moderately hyperopic 3- to 5-year-old children with normal VA and binocularity, failure for VA or binocularity was not common. With insufficient enrollment and retention, our study was unable to determine whether immediate glasses prescription reduces failure rate, but low failure rates suggest that immediate glasses prescription for these children may not be needed to prevent failure for VA and/or binocularity., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background and Purpose: According to the most recent consensus statement on management of sport-related concussion (SRC), athletes with suspected SRC should receive a comprehensive neurological examination. However, which measures to include in such an examination are not defined. Our objectives were to (1) evaluate test-retest reliability and normative data on vestibular and balance tests in athletes without SRC; (2) compare athletes with and without SRC on the subtests; and (3) identify subtests for concussion testing protocols., Methods: Healthy athletes (n = 87, mean age 20.6 years; standard deviation = 1.8 years; 39 female and 48 male) and athletes with SRC (n = 28, mean age 20.7 years; standard deviation = 1.9 years; 11 female and 17 male) were tested using rotary chair, cervical vestibular-evoked myogenic potential (c-VEMP), and the Sensory Organization Test (SOT). A subset (n = 43) were tested twice. We analyzed reliability of the tests, and compared results between athletes with and without SRC., Results: Reliability ranged from poor to strong. There was no significant difference between athletes with and without SRC for tests of peripheral vestibular function (ie, rotary chair and c-VEMP). Athletes with SRC had significantly worse scores (P < 0.05) on vestibular-ocular reflex (VOR) cancellation gain, subjective visual vertical and horizontal variance, and all conditions of the SOT., Discussion and Conclusion: SRC did not affect medium frequency VOR or saccular function. SRC did affect the ability to use vestibular inputs for perception of vertical and postural control, as well as ability to cancel the VOR.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A274).

Significance: Oculomotor tests in concussion commonly show impairment in smooth pursuit and saccadic function. Honing in on the systems likely to be affected by concussion will streamline use of oculomotor function as a supplemental diagnostic and prognostic tool, as well as improve our understanding of the pathophysiology of concussion., Purpose: This study investigates oculomotor function between concussed and healthy collegiate athletes and determines measurement test-retest reliability of those tools., Methods: Eighty-seven healthy athletes were recruited from a U.S. Division 1 sports university and completed a 30-minute vestibular ocular testing battery in an enclosed rotary chair system equipped with 100-Hz eye-tracking goggles. Forty-three individuals completed the battery twice. Twenty-eight individuals with a current diagnosis of concussion also completed the battery. All participants were aged 18 to 24 years. Bivariate statistical tests examined differences in scores across groups, and intraclass coefficients were computed to test reliability., Results: Concussed individuals had significantly longer saccadic, visual, and dual-task reaction times and reduced saccadic accuracy. There was no difference in optokinetic reflex gain, but few concussed individuals tolerated the task. Reaction time latencies and optokinetic gain show moderate test-retest reliability. Smooth pursuit tasks and saccadic accuracies showed poor test-retest reliability., Conclusions: Saccadic latency was the most sensitive oculomotor function to change after concussion and was reliable over time. Saccadic accuracy was significantly lower in the concussed group but had poor retest reliability. Optokinetic gain may warrant more investigation because of its high test-retest reliability and symptom provocation in concussion, despite not showing a significant difference between groups.

Purpose: The King-Devick test (KD) has been studied as a remove-from-play sideline test in college-age athletes and older; however, studies in younger athletes are limited. A cross-sectional study of the KD and other vision correlates was completed on school-aged athletes during pre-season physicals for a variety of sports to determine the repeatability of the KD. The study also evaluated how convergence, alignment, or pupil function contributed to a slower King-Devick baseline reading., Methods: Seven hundred eighty-five athletes underwent vision screenings in a hospital or school setting by trained/certified staff as part of pre-season physicals. Six hundred nineteen had KD testing completed per the manufacturer's suggested protocol and repeated. Other baseline vision testing included visual acuity, Modified Thorington testing for alignment, convergence testing, and pupil function using the NeurOptics (NPI-200) NPi., Results: The mean fastest, error-minimized KD time for all participants was 43.9 seconds(s) (SD ± 11.6, range 24-120). Median KD time got faster (+) with age (p < 0.0001). The inter-class correlation coefficient for all scores was 0.92. The absolute mean time difference for any two tests was 3.5 s (SD ± 2.5, range 0-23). There was no association between the best KD time and reduced NPC (p = 0.63), Modified Thorington measure of alignment (p = 0.55), or NPi pupil function (p = 0.79). The Bland Altman repeated measure limits of agreement was ±6.5 seconds for those in the 10th to12th grades, and ±10.2 seconds for those in the 6th to 9th grades., Conclusions: King-Devick score in junior high and high school athletes is variable but gets faster and more repeatable with increasing age. The KD does not correlate significantly with reduced convergence, alignment, or pupil function. Based on grouped data, a slowing of 10 seconds for younger athletes and 6 seconds for older athletes on a second administration represents a true difference in testing speed. Within-player variability should be considered when removal-from-play decisions are influenced by KD results.

Purpose: Academic difficulty is reported in children with prolonged post-concussive symptoms. Despite growing evidence that vestibular-ocular and vision-specific dysfunction are common in children after concussion, vision is rarely mentioned in return-to-learn protocols. The purpose of this project was to evaluate a cohort of children with prolonged post-concussive symptoms to determine if vision symptoms are associated with those reporting academic difficulty., Methods: Data were obtained from the Children's of Alabama Concussion Clinic REDCap dataset from the period January 2007 to October 2013. From this dataset of 1033 concussion events, a cohort of 276 children aged 5 to 18 years with three or more concussion-related symptoms present for 10 days or more was identified. A cross-sectional cohort study was undertaken to evaluate the association of concussion symptoms, SCAT2 scores, and demographic and concussion severity markers to reported educational difficulty among children with prolonged post-concussive symptoms. Univariate and multivariate logistic regression techniques were used to model the association of reported educational difficulty to self-reported vision abnormalities., Results: Mean age was 13.8 years. Median time since the concussive event was 21 days, with 33% (95/276) reporting their concussion more than 30 days before data collection. Academic difficulty was reported by 29% (79/270) and vision abnormalities in 46% (128/274). After model reduction, vision symptoms (OR 2.17, 95% CI 1.02, 4.62), hearing disturbance (OR 2.39, 95% CI 1.06, 5.36), and concentration difficulty (OR 21.62, 95% CI 9.50, 44.47) remained associated with academic difficulty. For those with symptoms 30 days or more after concussion, only vision (OR 3.15, 95% CI 1.06, 9.38) and concentration difficulty (OR 15.33, 95% CI 4.99, 47.05) remained statistically significant., Conclusions: Vision problems were commonly reported in children with concussions and were independently associated with those reporting academic difficulty. Comprehensive vision assessment should be considered in children reporting academic difficulty and in the development of return-to-learn protocols.

Purpose: High-quality optical coherence tomography (OCT) macular scans make it possible to distinguish a range of normal and diseased states by characterising foveal pit shape. Existing mathematical models lack the flexibility to capture all known pit variations and thus characterise the pit with limited accuracy. This study aimed to develop a new model that provides a more robust characterisation of individual foveal pit variations., Methods: A Sloped Piecemeal Gaussian (SPG) model, consisting of a linear combination of a tilted line and a piecemeal Gaussian function (two halves of a Gaussian connected by a separate straight line), was developed to fit retinal thickness data with the flexibility to characterise different degrees of pit asymmetry and pit bottom flatness. It fitted the raw pit data between the two rims of the fovea to improve accuracy. The model was tested on 3488 macular scans from both eyes of 581 young adults (376 myopes and 206 non-myopes, mean (S.D.) age 21.9 (1.4) years). Estimates for retinal thickness, wall height and slope, pit depth and width were derived from the best-fitting model curve. Ten variations of Gaussian and Difference of Gaussian models were fitted to the same scans and compared with the SPG model for goodness of fit (by Root mean square error, RMSE), model complexity (by the Bayesian Information Criteria) and model fidelity., Results: The SPG model produced excellent goodness of fit (mean RMSE = 4.25 and 3.89 μm; 95% CI: 4.20, 4.30 and 3.86, 3.93 for fitting horizontal and vertical profiles respectively). The SPG model showed pit asymmetry, with average nasal walls 17.6 (11.6) μm higher and 0.96 (0.61) ° steeper than temporal walls and average superior walls 7.0 (12.2) μm higher and 0.41 (0.65) ° steeper than the inferior walls. The SPG model also revealed a continuum of human foveal shapes, from round bottoms to extended flat bottoms (up to 563 μm). 49.1% of foveal profiles were best fitted with a flat bottom >30 μm wide. Compared with the other tested models, the SPG was the preferred model overall based on the Bayesian Information Criteria., Conclusions: The SPG is a new parsimonious mathematical model that improves upon other models by accounting for wall asymmetry and flat pit bottoms, providing an excellent fit and more faithful characterisation of typical foveal pit shapes and their known variations. This new model may be helpful in distinguishing normal foveal shape variations by refractive status as well by other characteristics such as sex, ethnicity and age., (© 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.)

Background: Some children have residual amblyopia after treatment with atropine eyedrops for amblyopia due to strabismus and/or anisometropia. We conducted a randomized clinical trial to evaluate the effectiveness of augmenting the effect of atropine by changing the lens over the fellow eye to plano in children with residual amblyopia., Methods: A total of 73 children 3 to <8 years of age (mean, 5.8 years) with stable residual amblyopia (range, 20/32 to 20/160, mean 20/63(+1)) were enrolled after at least 12 weeks of atropine treatment of the fellow eye. Participants were randomly assigned to continuing weekend atropine alone or wearing a plano lens over the fellow eye (while continuing atropine). The primary outcome was assessed at 10 weeks, and participants were followed until improvement ceased., Results: At the 10-week primary outcome visit, amblyopic-eye visual acuity had improved an average of 1.1 lines with the plano lens and 0.6 lines with atropine only (difference adjusted for baseline visual acuity = + 0.5 line; 95% CI, -0.1 to +1.2). At the primary outcome or later visit when the best-measured visual acuity was observed, the mean amblyopic-eye improvement from baseline was 1.9 lines with the plano lens and 0.8 lines with atropine only., Conclusions: When amblyopic-eye visual acuity stops improving with atropine treatment, there may be a small benefit to augmenting atropine therapy with a plano lens over the fellow eye. However, the effect was not statistically significant, and the large confidence interval raises the possibility of no benefit or a benefit larger than we observed. A larger study would be necessary to get a more precise estimate of the treatment effect., (Copyright © 2015 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.)