Office-based vergence and anti-suppression therapy for the treatment of small-to-moderate angle intermittent exotropia: A randomised clinical trial.

PURPOSE: To evaluate the short-term (1 week after completion of treatment) effect of office-based vergence and anti-suppression therapy (OBVAT) on the Office Control Score when compared to observation alone in children with small-to-moderate angle intermittent exotropia (IXT). METHODS: In this single-masked (examiner masked), two-arm, single-centre randomised clinical trial, 40 participants, 6 to <18 years of age with untreated IXT, were randomly assigned to OBVAT or observation alone. Participants assigned to therapy received 60 min of OBVAT with home reinforcement once per week for 16 weeks. Therapy included vergence, accommodation and anti-suppression techniques. The primary outcome measure was the comparison of the distance Office Control Score between the two groups at the primary outcome visit (i.e., 17-week follow-up visit). RESULTS: At the primary outcome visit, the OBVAT group (n = 20) had a significantly better distance Office Control Score (adjusted mean difference: -0.9; 95% CI: -0.2 to -1.5; p = 0.008; partial eta squared: 0.19) than the observation group (n = 16). Participants from the OBVAT group were more likely than those from the observation group to have ≥1 point of improvement at the 17-week visit (OBVAT group: 75%; Observation group: 25%; p = 0.006). CONCLUSIONS: In this randomised clinical trial of participants aged 6 to <18 years with IXT, we found that the OBVAT group had a significantly better distance Office Control Score than the observation group at the 17-week visit. This study provides the first data from a randomised clinical trial demonstrating the effectiveness of OBVAT for improving the control of IXT. Eye care practitioners should consider OBVAT as a viable, non-surgical treatment option for IXT. A full-scale randomised clinical trial investigating the long-term effectiveness of OBVAT in treating IXT is warranted.

Divergence excess and basic exotropia types of intermittent exotropia: a major review. Part 1: prevalence, classification, risk factors, natural history and clinical characteristics.

INTRODUCTION: Intermittent exotropia (IXT) is a common form of strabismus. It is an outward deviation of one eye typically when viewing at distance. Symptoms include, but are not limited to double vision, eyes feeling tired, excessive blinking, and reduced quality of life. Its clinical characteristics are distinctive from other types of strabismus. This paper provides a comprehensive review of prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT. METHODS: Search strategies involving combination of keywords including intermittent exotropia, exotropia, divergences excess, basic exotropia, prevalence, incidence, classification, terminology, risk factor, natural history, observation, angle of deviation, control, control score, symptom, quality of life, suppression, anomalous retinal correspondence, AC/A, accommodative convergence/accommodation, accommodative convergence, convergence, accommodation, vergence, incomitance and vertical were used in Medline. All English articles from 1900/01/01 to 2020/09/01 were reviewed. The reference list of the identified article was also checked for additional relevant article. Studies focused on animal model or strabismus associated with neurologic disorder or injury were excluded. RESULTS: The estimated prevalence of IXT in children ranges from 0.1% to 3.7%. Hypoxia at birth and being female are potential risk factors of IXT. Using validated measures of control, multicenter prospective studies showed that the rate of conversion from IXT to constant exotropia is low. The angle of deviation is the most reported outcome measure in studies of IXT. It is often used to represent the severity of the condition and has been suggested as one of the four core outcomes for studies of the surgical management of IXT. Control of exodeviation is one of the four suggested core outcomes for study of surgery of IXT and is considered the main parameter of disease severity. Several validated tools for quality of life score are available to evaluate the subjective severity of IXT. DISCUSSION: We reviewed the prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT. Further research into these areas, especially its clinical characteristics (e.g. suppression, dual retinal correspondence), will increase our understanding of this condition and potentially lead to better management of this common form of strabismus.

Reliability of step vergence method for assessing fusional vergence in intermittent exotropia.

PURPOSE: To evaluate the reliability of the step vergence method in measuring fusional vergence in subjects with intermittent exotropia. METHODS: Thirty-two Chinese participants aged 7-20 years with intermittent exotropia (excluding the convergence insufficiency type) were enrolled in this prospective study. At the eligibility screening, visual acuity, cover test and the Office Control Score were performed. For eligible participants at study visit 1, negative and positive fusional vergence at distance and near, eye dominance and the fusion maintenance test were performed. All eligible participants returned for study visit 2 on the same day (2-4 h later), and the testing was repeated. The primary outcome measures were the intra-class correlation coefficient, coefficient of repeatability and smallest detectable change in the break and recovery points of negative and positive fusional vergence between the two study visits. RESULTS: The intra-class correlation coefficient for different vergence parameters ranged from 0.64 to 0.87. The coefficient of repeatability and the smallest detectable change for the distance positive fusional vergence break point were ±20.5 and 13.1 ∆, respectively. There was no significant difference in any vergence parameter between the first and second visits. The coefficient of repeatability and the smallest detectable change in all distance vergence parameters were high when compared to the mean value. The association between distance vergence parameters and the Office Control Score was significant only when including subjects who failed to fuse at the beginning of the test. CONCLUSION: The data demonstrate that measurement of fusional vergence with a prism bar has low repeatability in subjects with intermittent exotropia. In these individuals, convergence ability at distance is compromised, whereas other vergence parameters are not adversely affected. While the step vergence method is a valuable test in daily practice, caution is warranted when using it in clinical research.

Vision therapy for intermittent exotropia: A case series

Introduction: We evaluated the effectiveness of office-based vergence/accommodative therapy with home reinforcement for intermittent exotropia in a private practice environment. Methods: This was a retrospective chart review study. Patients who received office-based vision therapy for intermittent exotropia in a private optometric clinic were reviewed. Patients with intermittent exotropia treated with and without strabismus surgery were both included. The pre-therapy baseline data were compared to the re-evaluation data obtained at the last therapy session. All patients received office-based vergence/accommodative therapy administered by a trained therapist during a 60 min office visit every one to two weeks, combined with home reinforcement for a minimum of 15 min, five times per week. The primary outcome measure in this study was the change in the Office Control Score from the pre-therapy visit to the post-therapy visit. The hypothesis was that office-based vergence/accommodative therapy would significantly improve the Office Control Score. Results: Forty patients aged from 5 to 22 years old fulfilled the inclusion criteria. Eight of them were postoperative patients. After treatment, there was a change of −1.1 ± 1.6 (p < 0.001, z = 3.73, effect size: 0.42) and −1.1 ± 1.4 (p < 0.001, z = 4.26, effect size: 0.48) in distance and near Office Control Score, respectively. In the subgroup analysis, significant improvements in the Office Control Score were observed in both the operated and unoperated intermittent exotropes at distance and near. Conclusion: This study showed that office-based vergence/accommodative therapy with home reinforcement significantly improved the distance and near control of exodeviation in both operated and unoperated intermittent exotropia patients in a private practice environment. (AU)

Maintenance of normal fusion in intermittent exotropia.

PURPOSE: To evaluate the reliability of the Bagolini filter bar and striated lenses for measuring the fusion maintenance score, which is the ability of participants with intermittent exotropia to maintain normal sensorimotor fusion. METHODS: Thirty-two Chinese participants aged 7-20 years with intermittent exotropia (excluding the convergence insufficiency type) were enrolled in this prospective study. At the eligibility screening, visual acuity, cover test and assessment of the office control score were performed. At study visit 1, eligible participants underwent negative and positive fusional vergence tests at far and near, eye dominance test and the fusion maintenance test. All eligible participants returned for study visit 2 on the same day (2-4 h later) and the testing was repeated. The primary outcome measure was the intra-class correlation coefficient of the fusion maintenance score between the two study visits. RESULTS: The intra-class correlation coefficient of the fusion maintenance score was 0.84, indicating good reliability. There was no significant difference (mean difference = 0.05, p = 0.95) between the fusion maintenance scores for the first (5.62) and second study visits (5.57). The coefficient of repeatability and the smallest detectable change for the fusion maintenance scores were 7.6 and 6.3, respectively. The fusion maintenance score was significantly associated with the distance (Spearman correlation -0.57, p < 0.001) and near (Spearman correlation -0.4, p = 0.02) office control scores. CONCLUSION: These data demonstrate that the fusion maintenance score is a reliable tool to evaluate sensorimotor fusion in intermittent exotropia. These results suggest that the fusion maintenance score may be a useful outcome measure in future clinical trials to evaluate the effectiveness of treatments for intermittent exotropia.

Vision therapy for intermittent exotropia: A case series.

INTRODUCTION: We evaluated the effectiveness of office-based vergence/accommodative therapy with home reinforcement for intermittent exotropia in a private practice environment. METHODS: This was a retrospective chart review study. Patients who received office-based vision therapy for intermittent exotropia in a private optometric clinic were reviewed. Patients with intermittent exotropia treated with and without strabismus surgery were both included. The pre-therapy baseline data were compared to the re-evaluation data obtained at the last therapy session. All patients received office-based vergence/accommodative therapy administered by a trained therapist during a 60 min office visit every one to two weeks, combined with home reinforcement for a minimum of 15 min, five times per week. The primary outcome measure in this study was the change in the Office Control Score from the pre-therapy visit to the post-therapy visit. The hypothesis was that office-based vergence/accommodative therapy would significantly improve the Office Control Score. RESULTS: Forty patients aged from 5 to 22 years old fulfilled the inclusion criteria. Eight of them were postoperative patients. After treatment, there was a change of -1.1 ±â€¯1.6 (p < 0.001, z = 3.73, effect size: 0.42) and -1.1 ±â€¯1.4 (p < 0.001, z = 4.26, effect size: 0.48) in distance and near Office Control Score, respectively. In the subgroup analysis, significant improvements in the Office Control Score were observed in both the operated and unoperated intermittent exotropes at distance and near. CONCLUSION: This study showed that office-based vergence/accommodative therapy with home reinforcement significantly improved the distance and near control of exodeviation in both operated and unoperated intermittent exotropia patients in a private practice environment.

Office-based Vergence and Accommodative Therapy for the Treatment of Intermittent Exotropia: A Pilot Study.

SIGNIFICANCE: This study will help to demonstrate the potential value of office-based vergence/accommodative therapy for the treatment of intermittent exotropia and provide data that can be used for planning future clinical trials. PURPOSE: This study was designed to evaluate changes in the office control score after office-based vergence/accommodative therapy for intermittent exotropia. METHODS: This was a prospective, unmasked pilot study. Fourteen Chinese participants aged 6 to 18 years with intermittent exotropia (excluding the convergence insufficiency type) were enrolled. All participants received 60 minutes of office-based vergence/accommodative therapy with home reinforcement once per week for 12 weeks. Therapy included vergence, accommodation, saccades and pursuits, antisuppression, and monocular fixation in binocular field techniques. The primary outcome measure was the change in the office control score from the baseline visit to the 13-week outcome visit. RESULTS: All participants completed the study. The office control score at distance changed by -1.0 (95% confidence interval [CI] = -1.6 to -0.4; P = .005; Cohen's d effect size, 0.93). The distant Look And Cover, then Ten seconds Observation Scale for Exotropia score and distant Newcastle control score total score changed by -0.7 (95% CI, -1.2 to -0.2; P = .02; Cohen's d effect size, 0.55) and -1.9 (95% CI, -2.8 to -1.0; P < .001; Cohen's d effect size, 1.37), respectively. Although there was no significant change in the angle of distance exodeviation (-1.8 prism diopter [Δ] less exodeviation; 95% CI, -3.74 to 0.14Δ; P = .11), a significant change was observed in the near angle (-4.4Δ less exodeviation; 95% CI, -7.3 to -1.5Δ; P = .01; Cohen's d effect size, 0.79). There was no significant change in stereopsis or the Chinese Intermittent Exotropia Questionnaire score. CONCLUSIONS: In this select group of children with intermittent exotropia, 12 weeks of office-based vergence/accommodative therapy with home reinforcement resulted in a statistically and clinically significant improvement in the distance control of exodeviation and the near exodeviation magnitude. These results suggest that there is a need for a randomized clinical trial designed to determine the effectiveness of vision therapy as a treatment modality for intermittent exotropia.

Vergence and Accommodative Dysfunctions in Emmetropic and Myopic Chinese Young Adults.

PURPOSE: To investigate the association between refractive error and common binocular vision and accommodative dysfunctions in Chinese adults and to report the percentage of these disorders in this sample population. METHODS: This was a single-site, prospective cross-sectional clinic-based study. A total of 415 Chinese participants aged between 21 and 38 years were grouped into 4 refractive error groups (emmetropia, low, moderate, and high myopia) based on the spherical equivalent power of noncycloplegic refraction. Baseline testing including binocular vision and accommodative testing was performed on all eligible participants. A multiple-sign classification system was used to analyze these data for the diagnosis of common nonstrabismic binocular vision and accommodative dysfunctions. Associations between the diagnosis and refractive error groupings were examined by the chi-square test for the linear trend. RESULTS: Associations with refractive error groupings were found for convergence insufficiency (p=0.008, r = -0.13) and divergence insufficiency (p=0.008, r = 0.131). The 3 most common dysfunctions in this sample population were basic exophoria (10.8%), convergence insufficiency (9.6%), and divergence insufficiency (7.0%). Approximately 40% of the sample population demonstrated at least one type of binocular vision dysfunction. CONCLUSION: Convergence insufficiency and divergence insufficiency were associated with refractive error groupings. Binocular vision dysfunction was a common finding in this sample population.

Effect of Vision Therapy on Accommodative Lag in Myopic Children: A Randomized Clinical Trial.

SIGNIFICANCE: Accommodative dysfunction has been suggested to be related to the development and progression of myopia. Office-based accommodative/vergence therapy (OBAVT) improved accommodative facility in Chinese myopic children, but it is unclear if such improvement has a role in decreasing myopic progression. PURPOSE: The purpose of this study was to compare the effects of OBAVT with home reinforcement and office-based placebo therapy (OBPT) as a treatment to improve accommodative functions (i.e., lag, amplitude, and facility) in myopic children with poor accommodative accuracy. METHODS: This was a prospective, single-masked, randomized clinical trial. Thirty-four Chinese children 8 to 12 years old with myopia and at least 1 diopter of lag of accommodation measured by autorefraction were enrolled. The participants were randomly assigned to the OBAVT or OBPT group. The primary outcome measure was the change in the monocular lag of accommodation from the baseline visit to the 13-week visit measured by a Shin-Nippon open-field autorefractor. Secondary outcome measures were changes in accommodative amplitude and monocular accommodative facility. RESULTS: A total of 33 participants completed the study. After 12 weeks of treatment, there were significant improvements in the lag of accommodation in both the OBAVT and OBPT groups (OBAVT: -0.30 ± 0.29 diopters [P < .001; Cohen's d effect size, 1.29]; OBPT: -0.24 ± 0.30 diopters [P = .005; Cohen's d effect size, 1.24]). There was no statistically significant difference between the improvements in the two groups (P = .50). There was statistically significant improvement in monocular accommodative facility only in the OBAVT group (OBAVT: 7.7 ± 4.7 cycles per minute [P < .001; Cohen's d effect size, 2.20]; OBPT: 1.9 ± 4.4 cycles per minute [P = .072]). The change in the OBAVT group was statistically significantly larger than that in the OBPT group (P < .001). CONCLUSIONS: Office-based accommodative/vergence therapy was no more effective than OBPT in reducing the lag of accommodation in children 8 to 12 years old with low to moderate myopia. It did improve accommodative facility in Chinese myopic children, but it is unclear if such an improvement has a role in decreasing myopic progression.

Convergence insufficiency in Chinese high school students.

BACKGROUND: The frequency of convergence insufficiency was determined in a sample of Chinese high school students. The associations between the frequency of convergence insufficiency, gender, refractive error and accommodative insufficiency were investigated. METHODS: This was a single-site, prospective cross-sectional study. In total, 928 eligible teenagers (mean age 15.9 ± 0.8) from a local high school in Guangzhou, Guangdong Province, China participated in this study. Refraction and binocular vision tests were performed on all eligible participants. The following three signs were used to classify participants: sign 1, exophoria at near at least 4▵ greater than at far; sign 2, receded near point of convergence (≥ 6 cm break point); and sign 3, insufficient near positive fusional vergence (that is, failing Sheard's criterion or ≤ 15▵ break point). Diagnostic groups of convergence insufficiency classification were defined as follows: (1) 3-Sign convergence insufficiency (all three signs present); (2) 2-Sign convergence insufficiency (sign 1 plus sign 2 or 3); (3) 1-Sign convergence insufficiency (sign 1 only); and (4) no convergence insufficiency (that is, participants not classified into one of the above groups). RESULTS: The number and frequency of individuals with 3-Sign, 2-Sign, and 1-Sign convergence insufficiency as well as no convergence insufficiency group were 25 (2.7 per cent), 119 (12.8 per cent), 303 (32.6 per cent) and 481 (51.8 per cent), respectively. Gender (χ2 = 36.6, df = 3, p < 0.001), refractive error grouping (χ2 = 37.7, df = 9, p < 0.001) and accommodative insufficiency (χ2 = 15.4, df = 3, p = 0.002) were all significantly associated with convergence insufficiency. Male gender, hyperopia, or accommodative insufficiency were more likely to be classified with 3-Sign convergence insufficiency. The frequency of accommodative insufficiency was 9.5 per cent (88 of 928 participants). CONCLUSION: Compared to the data from school- and clinic-based populations in the USA and South Africa, the data from this sample of Chinese high school students showed a lower frequency of 3-Sign convergence insufficiency (2.7 per cent). Convergence insufficiency was associated with refractive error, gender and accommodative insufficiency.

Effect of Vision Therapy on Accommodation in Myopic Chinese Children.

Introduction. We evaluated the effectiveness of office-based accommodative/vergence therapy (OBAVT) with home reinforcement to improve accommodative function in myopic children with poor accommodative response. Methods. This was a prospective unmasked pilot study. 14 Chinese myopic children aged 8 to 12 years with at least 1 D of lag of accommodation were enrolled. All subjects received 12 weeks of 60-minute office-based accommodative/vergence therapy (OBAVT) with home reinforcement. Primary outcome measure was the change in monocular lag of accommodation from baseline visit to 12-week visit measured by Shinnipon open-field autorefractor. Secondary outcome measures were the changes in accommodative amplitude and monocular accommodative facility. Results. All participants completed the study. The lag of accommodation at baseline visit was 1.29 ± 0.21 D and it was reduced to 0.84 ± 0.19 D at 12-week visit. This difference (-0.46 ± 0.22 D; 95% confidence interval: -0.33 to -0.58 D) is statistically significant (p < 0.0001). OBAVT also increased the amplitude and facility by 3.66 ± 3.36 D (p = 0.0013; 95% confidence interval: 1.72 to 5.60 D) and 10.9 ± 4.8 cpm (p < 0.0001; 95% confidence interval: 8.1 to 13.6 cpm), respectively. Conclusion. Standardized 12 weeks of OBAVT with home reinforcement is able to significantly reduce monocular lag of accommodation and increase monocular accommodative amplitude and facility. A randomized clinical trial designed to investigate the effect of vision therapy on myopia progression is warranted.