Binocular game versus part-time patching for treatment of anisometropic amblyopia in Chinese children: a randomised clinical trial

High-Adherence Dichoptic Treatment Versus Patching in Anisometropic and Small Angle Strabismus Amblyopia: A Randomized Controlled Trial

PURPOSE

To compare the effectiveness and safety of a novel binocular eye-tracking-based-home-treatment (CureSight) to patching for the treatment of amblyopia.

DESIGN

Prospective, masked, multicenter randomized controlled trial.

METHODS

One hundred forty-nine children 4 to < 9 years with anisometropic, small-angle strabismic, or mixed-mechanism amblyopia were randomized to either binocular dichoptic treatment (n=75) or patching (n=74). The binocular dichoptic treatment group used the CureSight system for 90 min/day, 5 days/week for 16 weeks (120 hours). The patching group received 2-hour patching 7 days/week (224 hours). The primary outcome was the mean improvement from baseline in amblyopic eye visual acuity (VA) to week 16 in both study groups (non-inferiority of ≤0.10 logarithm of the minimum angle of resolution [logMAR]).

RESULTS

In the modified intent-to-treat (mITT) group, the mean improvement from baseline at week 16 in the binocular treatment group was noninferior to patching group improvement (0.034 logMAR [95% CI -0.009 to 0.076]). In the per-protocol (PP) dataset, the mean improvement from baseline at week 16 in the binocular treatment group was superior to patching group improvement (0.05 logMAR ([95% CI; 0.007 to 0.097]). There was no significant between-group difference in the magnitude of improvement in stereoacuity in the mITT and the PP datasets. Median adherence in the mITT binocular treatment group (94.0%) was also significantly higher than in the patching group (83.9%; p=0.0038).

CONCLUSIONS

A binocular, eye-tracking-based amblyopia home treatment is noninferior to, and produced better visual outcomes than, patching in children with anisometropic, small angle strabismus and mixed mechanism amblyopia.

Evaluating Eye Tracking During Dichoptic Video Viewing With Varied Fellow Eye Contrasts in Amblyopia

Purpose

This study uses eye tracking to investigate how varying fellow eye (FE) contrast during dichoptic video viewing influences eye movement patterns, and their associations with interocular suppression, visual acuity, and stereoacuity deficit in amblyopia.

Methods

Eye movements of 27 amblyopic and 8 healthy control participants were recorded during dichoptic viewing of stationary dots and videos with FE contrasts (100%, 50%, 25%, and 10%). Analysis included durations the amblyopic and FE spent in different stimulus regions, fixation switches, and eye deviation, and correlating these with suppression, visual acuity, and stereoacuity.

Results

Participants with pronounced suppression, visual acuity, and stereoacuity deficits demonstrated reduced amblyopic eye fixation in the amblyopic eye (AE) region at 100% FE contrast. Lowering FE contrast increased amblyopic eye duration in stimuli presented within the AE region, notably in anisometropic and treated strabismic participants, and strabismic participants exhibiting fixation switches during viewing of dichoptic stationary dots. Even at lower FE contrasts, participants with greater stereoacuity and visual acuity deficits continued to exhibit diminished AE fixation in the AE region. Increased eye deviation was seen in strabismic participants with lowering of FE contrasts.

Conclusions

Dichoptic contrast modulation holds promise for reducing suppression with responses varying by amblyopia type and visual function deficits. Larger strabismic angles may hinder binocular benefits of dichoptic treatments. Fixation switches may serve as an indicator of favorable outcomes. Eye tracking is crucial for understanding these dynamics, providing essential insights into visual attention dynamics of the FE and AE, and may serve as a valuable tool in optimization of amblyopia treatments.

Patch-free streaming contrast-rebalanced dichoptic cartoons versus patching for treatment of amblyopia in children aged 3 to 5 years: a pilot, randomized clinical trial

BACKGROUND

We developed and tested a dichoptic treatment designed for younger children that can be viewed freely and involves a dichoptic manipulation of a popular animation series that enables contrast-rebalancing without disrupting fusion. Our aim was to assess whether this novel amblyopia treatment is superior to patching in children aged 3-5 years.

METHODS

A total of 34 children with amblyopia were randomly assigned to contrast-rebalanced dichoptic cartoons (4 hours/week) or patching (14 hours/week) for 2 weeks. Children in the cartoon group continued watching cartoons for an additional 2 weeks. Designed to target the youngest and most treatable children, the dichoptic cartoons presented the entire scene to the amblyopic eye at 100% contrast, while the fellow eye view was presented at reduced contrast with the main character omitted. Best-corrected visual acuity (BCVA), stereoacuity, suppression, and manual dexterity were measured at each visit.

RESULTS

After 2 weeks, improvement in amblyopic eye BCVA was greater for dichoptic treatment than for patching, with a mean improvement of 0.11 ± 0.08 versus 0.06 ± 0.09 logMAR, respectively (P = 0.04). Stereoacuity, suppression, and manual dexterity did not improve significantly more in the dichoptic group than the patching group at 2 weeks. After 4 weeks of dichoptic cartoon treatment, mean visual acuity improvement in the dichoptic group was 0.16 logMAR (95% CI, 0.10-0.21).

CONCLUSIONS

In our study cohort, a contrast-rebalanced dichoptic cartoon was more effective than patching in treating childhood amblyopia after 2 weeks. Dichoptic cartoons that rebalance contrast to overcome suppression provide an additional treatment option for amblyopia in young children.

Computer-Assisted Visual Training in Children and Adolescents with Developmental Visual Disorders

BACKGROUND

In this systematic review, we address the question whether children and adolescents with developmental visual disorders benefit from computer-assisted visual training.

METHODS

Systematic literature searches were carried out in three bibliographic databases (initial search in October 2021) and trial registries. Included were randomized controlled trials that evaluated the efficacy of computer-assisted visual training in children and adolescents with developmental visual disorders in comparison to no training, sham training, or conservative treatment.

RESULTS

The inclusion criteria were met by 17 trials (with a total of 1323 children and adolescents) focusing on binocular or monocular computer-assisted visual training for the treatment of amblyopia. In these trials, visual training was carried out for 2 to 24 weeks, either as "stand alone" therapy or in addition to occlusion therapy. Six trials showed a statistically significant difference in favor of the visual training for the outcome "best corrected visual acuity of the amblyopic eye." However, this difference was small and mostly below the threshold of clinical relevance of -0.05 logMAR (equivalent to an improvement of 0.5 lines on the eye chart, or 2.5 letters per line). Only few data were available for the outcomes "binocular vision" and "adverse events"; the differences between the groups were similarly small.

CONCLUSION

The currently available data do not permit any firm conclusions regarding the efficacy of visual training in children and adolescents with amblyopia. Moreover, treatment adherence was often insufficient and the treatment durations in the trials was relatively short. No results from randomized trials have yet been published with respect to other developmental visual disorders (refractive errors, strabismus).

Characterizing amblyopic perception under non-rivalrous viewing conditions

Current assessments of interocular interactions in amblyopia often use rivalrous stimuli, with conflicting stimuli in each eye, which does not reflect vision under typical circumstances. Here we measure interocular interactions in observers with amblyopia, strabismus with equal vision, and controls using a non-rivalrous stimulus. Observers used a joystick to continuously report the perceived binocular contrast of dichoptic grating stimuli, identical except that the stimulus was contrast-modulated independently in each eye over time. Consistent with previous studies, a model predicting the time-course of perceived contrast found increased amblyopic eye attenuation, and reduced contrast normalization of the fellow eye by the amblyopic eye, in amblyopic participants compared to controls. However, these suppressive interocular effects were weaker than those found in previous studies, suggesting that rivalrous stimuli may overestimate the effects of amblyopia on interocular interactions during naturalistic viewing conditions.

Effectiveness of binocular therapy as a complementary treatment of part-time patching in older amblyopic children: a randomized clinical trial

PURPOSE

To assess the effectiveness of combined use of stereoscopic 3D video movies and part-time patching in treating older amblyopic children with poor response or compliance to traditional patching treatments and comparing this combined treatment with patching alone.

METHODS

Thirty-two children aged 5-12 years with amblyopia associated with anisometropia, strabismus, or both were recruited in a randomized clinical trial. Eligible participants were assigned randomly to the combined and patching groups. Here, binocular treatment refers to using the Bangerter filter to blur the fellow eye and subsequently watching a close-up 3D movie with large parallax. The primary outcome was amblyopic eye (AE) best-corrected visual acuity (BCVA) improvement at six weeks. In addition, secondary outcomes included BCVA of AE improvement at three weeks and change of stereoacuity.

RESULTS

Of 32 participants, mean (SD) age was 6.63 (1.46) years, and 19 (59%) were female. At 6 weeks, mean (SD) amblyopic eye VA improved by 0.17 ± 0.08 logMAR (2-sided 95% CI, 0.13 to 0.22; F = 57.2, p < 0.01) and 0.05 ± 0.04 logMAR (2-sided 95% CI, 0.05 to 0.09; F = 8.73, p = 0.01) in the combined and patching groups, respectively. The difference was statistically significant (mean difference, 0.13 logMAR [1.3 line]; 95% CI, 0.08-0.17 logMAR [0.8-1.7 lines]; t25 = 5.65, p < 0 .01). After treatment, only the combined group had significantly improved stereoacuity, such as binocular function score (median [interquartile range], 2.30 [2.23 to 2.68] vs. 1.69 [1.60 to 2.30] log arcsec; paired, z = -3.53, p < 0.01), and mean stereoacuity gain was 0.47 log arcsec (± 0.22). Changes in other types of stereoacuity were similar.

CONCLUSION

Our laboratory-based binocular treatment strategy engaged a high level of compliance that led to a substantial gain in visual function after a short period of treatment for older amblyopic children having poor response or compliance to traditional patching treatments. Notably, the improving stereoacuity showed a greater advantage.

Learning to see in depth

Stereopsis provides us with a vivid impression of the depth and distance of objects in our 3- dimensional world. Stereopsis is important for a number of everyday visual tasks, including (but not limited to) reaching and grasping, fine visuo-motor control, and navigating in our world. This review briefly discusses the neural substrate for normal binocular vision and stereopsis and its development in primates; outlines some of the issues and limitations of stereopsis tests and examines some of the factors that limit the typical development of stereopsis and the causes and consequences of stereo-deficiency and stereo-blindness. Finally, we review several approaches to improving or recovering stereopsis in both neurotypical individuals and those with stereo-deficiency and stereo-blindness and outline some emerging strategies for improving stereopsis.

Amblyopia and fixation eye movements

Amblyopia is a neurodevelopmental disorder caused by abnormal visual experience in early life that affects 3-5% of the population. Amblyopia results in a host of monocular and binocular visual afferent function deficits including reduced visual acuity, contrast sensitivity, depth perception, interocular suppression, and efferent function abnormalities such as unstable and inaccurate fixation. Conventional treatments such as patching therapy and newer dichoptic treatments are not always successful as 30-40% of patients experience recurrence/regression of amblyopia. There are numerous review articles focused on visual afferent function deficits and treatment modalities and outcomes in amblyopia. Recently, the advent of high spatial and temporal resolution eye trackers has spurred studies on fixation eye movements (FEMs) in healthy controls and neurologic and ophthalmic disorders. In this focused review, we will summarize studies evaluating FEM abnormalities in amblyopia. We will first describe the common devices and techniques used to quantify fixation abnormalities, and then highlight the importance of systematically evaluating the eye movements under different viewing conditions and describe the parameters crucial in assessing FEM abnormalities in amblyopia. We will summarize the evidence suggesting that FEM abnormalities are not limited to the amblyopic eye only but also affects the fellow eye and that FEM abnormalities can serve as biomarkers to predict the impact of amblyopia on visual functions. Beyond diagnosis, we will discuss the treatment and prognostic implications of the evaluation of FEM abnormalities in clinical practice.

Binocular treatment for individual with amblyopia: A systematic review and meta-analysis

OBJECTIVE

To assess the efficacy of binocular treatment for individual with amblyopia.

METHODS

In this meta-analysis, a comprehensive search of literatures was performed from PubMed, Embase, Cochrane Library and Web of Science databases up to December 21, 2020. Sensitivity analysis was performed for all outcomes. The Begg's test was used to assess the publication bias. Heterogeneity test was conducted for each effect indicator. Indicators were analyzed by random-effects model when the heterogeneity statistic I2 ≥ 50%, on the contrary, indicators were analyzed by fixed-effect model. Standard mean difference (SMD) or weighted mean difference (WMD) was adopted as effect indicators, and the effect amount was expressed as 95% confidence intervals (CIs).

RESULTS

A total of 13 literatures including 1146 participants were finally enrolled, with 595 in the intervention group and 551 in the control group. The results indicated that the improvement of amblyopic eye visual acuity [SMD: 0.882, 95%CI: (0.152, 1.613), P = 0.018] in binocular treatment group was better than that in control group. And binocular treatment could improve stereo acuity in individual with amblyopia [WMD: 0.138, 95%CI: (0.068, 0.208), P < 0.001].

CONCLUSION

Binocular treatment may be beneficial to visual acuity, stereo acuity and binocular function improvement for individual with amblyopia. In clinical practice, binocular treatment can be used as one of the treatments for individual with amblyopia.

Fixation instability, astigmatism, and lack of stereopsis as factors impeding recovery of binocular balance in amblyopia following binocular therapy

Dichoptic therapy is a promising method for improving vision in pediatric and adult patients with amblyopia. However, a systematic understanding about changes in specific visual functions and substantial variation of effect among patients is lacking. Utilizing a novel stereoscopic augmented-reality based training program, 24 pediatric and 18 adult patients were trained for 20 h along a three-month time course with a one-month post-training follow-up for pediatric patients. Changes in stereopsis, distance and near visual acuity, and contrast sensitivity for amblyopic and fellow eyes were measured, and interocular differences were analyzed. To reveal what contributes to successful dichoptic therapy, ANCOVA models were used to analyze progress, considering clinical baseline parameters as covariates that are potential requirements for amblyopic recovery. Significant and lasting improvements have been achieved in stereoacuity, interocular near visual acuity, and interocular contrast sensitivity. Importantly, astigmatism, fixation instability, and lack of stereopsis were major limiting factors for visual acuity, stereoacuity, and contrast sensitivity recovery, respectively. The results demonstrate the feasibility of treatment-efficacy prediction in certain aspects of dichoptic amblyopia therapy. Furthermore, our findings may aid in developing personalized therapeutic protocols, capable of considering individual clinical status, to help clinicians in tailoring therapy to patient profiles for better outcome.

Recent Treatment Advances in Amblyopia

Occlusion therapy has a long history as the gold standard treatment for amblyopia. Over the past two decades, large multicenter randomized controlled trials and objective dose-monitoring studies have characterized the effects of refractive correction, patching, and atropine penalization, providing insights into the impact of factors such as age and treatment dose. More recent approaches, whose development has been accelerated by advances in technology, are designed to provide different stimulation to the amblyopic eye and the fellow eye. This review explores a variety of such dichoptic approaches, categorized according to whether they primarily feature requisite use of the amblyopic eye in the face of fellow-eye masking, integration of visual information from both eyes, or reduction of stimulus salience in the fellow eye. It is still unclear whether dichoptic treatments are superior to traditional, low-cost treatment methods or whether their therapeutic mechanisms are fundamentally different from those of established treatments. Expected final online publication date for the Annual Review of Vision Science, Volume 8 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Randomized clinical trial of streaming dichoptic movies versus patching for treatment of amblyopia in children aged 3 to 7 years

Contrast-rebalanced dichoptic movies have been shown to be an effective binocular treatment for amblyopia in the laboratory. Yet, at-home therapy is a more practical approach. In a randomized clinical trial, we compared dichoptic movies, streamed at-home on a handheld 3D-enabled game console, versus patching as amblyopia treatment. Sixty-five amblyopic children (3–7 years; 20/32–125) were randomly assigned to one of two parallel arms, binocular treatment (3 movies/week) or patching (14 h/week). The primary outcome, change in best corrected visual acuity (BCVA) at the 2-week visit was completed by 28 and 30, respectively. After the primary outcome, both groups of children had the option to complete up to 6 weeks of binocular treatment. At the 2-week primary outcome visit, BCVA had improved in the movie (0.07 ± 0.02 logMAR; p < .001) and patching (0.06 ± 0.01 logMAR; p < 0.001) groups. There was no significant difference between groups (CI₉₅%: − 0.02 to 0.04; p = .48). Visual acuity improved in both groups with binocular treatment up to 6 weeks (0.15 and 0.18 logMAR improvement, respectively). This novel, at-home, binocular movie treatment improved amblyopic eye BCVA after 2 weeks (similar to patching), with additional improvement up to 6 weeks. Repeated binocular visual experience with contrast-rebalanced binocular movies provides an additional treatment option for amblyopia.

Clincaltrials.gov identifier: NCT03825107 (31/01/2019).

Recent Advances in Screening and Treatment for Amblyopia

Amblyopia is the most common cause of monocular visual impairment in children, with a prevalence of 2-3%. Not only is visual acuity reduced in one eye but binocular vision is affected, fellow eye deficits may be present, eye-hand coordination and reading can be affected, and self-perception may be diminished. New technologies for preschool vision screening hold promise for accessible, early, and accurate detection of amblyopia. Together with recent advances in our theoretical understanding of amblyopia and technological advances in amblyopia treatment, we anticipate improved visual outcomes for children affected by this very common eye condition. This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.

Comparison of binocular game and patching in treating mild to moderate anisometropic amblyopia: a study protocol for a randomized controlled trial

BACKGROUND

Amblyopia, as a neurodevelopmental preventable visual disorder, affects approximately 1.1 % in Asia. A binocular approach to treating amblyopia has been recently proposed. Whether the binocular playing game treatment is comparable to patching treatment needs further randomized clinical trials. To address this, the present research, designs, develops, and evaluates a new binocular game to treat amblyopia.

METHODS

This study has been designed as a non-inferiority, randomized, two parallel-group, controlled trial. Forty-four patients between 4 and 12 years diagnosed with amblyopia will be randomly assigned to the control and intervention groups. In the intervention group, amblyopia treatment is provided with red-green anaglyphic glasses and a red filter placed in front of the amblyopic eye, along with a game to be played for 30 min twice a day. Those in the control group will receive patch therapy according to amblyopia treatment study protocol. The primary outcome is to change visual acuity in the amblyopic eye from the baseline to 3 months after randomization.

ETHICS AND DISSEMINATION

The Ethics Committee of Mashhad University of Medical sciences' approval date was February 28, 2018, with a reference code of IR.MUMS.fm.REC.1396.783. Thus far, the recruitment of participants has not been completed and is scheduled to end in September 2021. The results will be disseminated in a peer-reviewed journal.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials IRCT20180217038768N1 . Registered on 22 April 2019.

Binocular treatment for amblyopia: A meta-analysis of randomized clinical trials

BACKGROUND

To date, there is still no consensus regarding the effect of binocular treatment for amblyopia. The purpose of this systematic review and meta-analysis was to summarize the available evidence to determine whether binocular treatment is more effective than patching in children with amblyopia.

METHODS

Four electronic databases (PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials) were searched for studies that compared binocular treatment and patching in children with amblyopia. The outcome measures were visual acuity and stereopsis. Pooled effects sizes were calculated with a random-effect model. The standardized difference in means (SDM) with 95% confidence intervals (CI) was calculated. Sensitivity analysis and assessment of publication bias were performed.

RESULTS

Five randomized clinical trials were included. No significant difference in visual acuity between patients treated with binocular treatment and patching was observed (SDM = -0.12; 95% CI: -0.45-0.20; P = 0.464). No significant difference in stereopsis between patients treated with binocular treatment and patching was observed (SDM = -0.07; 95% CI: -0.61-0.48; P = 0.809). For both variables, the between-study heterogeneity was high (respectively, I2 = 61% and I2 = 57%).

CONCLUSIONS

This meta-analysis found no convincing evidence supporting the efficacy of binocular treatment as an alternative to conventional patching. Therefore, the binocular treatment cannot fully replace traditional treatment but, to date, it can be considered a valid complementary therapy in peculiar cases. Further studies are required to determine whether more engaging therapies and new treatment protocols are more effective.

Efficacy of vision-based treatments for children and teens with amblyopia: a systematic review and meta-analysis of randomised controlled trials

Objective

To identify differences in efficacy between vision-based treatments for improving visual acuity (VA) of the amblyopic eye in persons aged 4-17 years old.

Data sources

Ovid Embase, PubMed (Medline), the Cochrane Library, Vision Cite and Scopus were systematically searched from 1975 to 17 June 2020.

Methods

Two independent reviewers screened search results for randomised controlled trials of vision-based amblyopia treatments that specified change in amblyopic eye VA (logMAR) as the primary outcome measure. Quality was assessed via risk of bias and GRADE (Grading of Recommendations, Assessment, Development, and Evaluations).

Results

Of the 3346 studies identified, 36 were included in a narrative synthesis. A random effects meta-analysis (five studies) compared the efficacy of binocular treatments versus patching: mean difference -0.03 logMAR; 95% CI 0.01 to 0.04 (p<0.001), favouring patching. An exploratory study-level regression (18 studies) showed no statistically significant differences between vision-based treatments and a reference group of 2-5 hours of patching. Age, sample size and pre-randomisation optical treatment were not statistically significantly associated with changes in amblyopic eye acuity. A network meta-analysis (26 studies) comparing vision-based treatments to patching 2-5 hours found one statistically significant comparison, namely, the favouring of a combination of two treatment arms comparing combination and binocular treatments, against patching 2-5 hours: standard mean difference: 2.63; 95% CI 1.18 to 4.09. However, this result was an indirect comparison calculated from a single study. A linear regression analysis (17 studies) found a significant relationship between adherence and effect size, but the model did not completely fit the data: regression coefficient 0.022; 95% CI 0.004 to 0.040 (p=0.02).

Conclusion

We found no clinically relevant differences in treatment efficacy between the treatments included in this review. Adherence to the prescribed hours of treatment varied considerably and may have had an effect on treatment success.

Comparison between binocular therapy and patching for treatment of amblyopia: a meta-analysis of randomised controlled trials

Several studies have compared binocular therapy and patching for the treatment of amblyopia. However, most of them involved a small number of cases and reported controversial results. Thus, the benefit of binocular therapy remains to be confirmed. We conducted a meta-analysis to evaluate the efficacy of binocular therapy versus patching and to testify whether binocular therapy could become supplementary method in children with amblyopia. Randomised controlled trials that evaluated the efficacy of binocular therapy for amblyopia versus patching were identified using PubMed, Embase, Cochrane Library, Ovid, Web of Science, ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform. Data screening, extraction and quality assessment were performed independently by two researchers. Six trials were identified and analysed to compare binocular therapy (708 eyes) with patching (664 eyes) for change in best-corrected visual acuity and stereoacuity. Efficacy estimates were evaluated by standard mean difference (SMD) and 95% CI. The best-corrected visual acuity in binocular group was better than that of in patching group (SMD=-0.21 logarithm of the minimum angle of resolution (log MAR), 95% CI of -0.50 to 0.08 log MAR, p=0.003). The results showed statistically significant difference in the change of best-corrected visual acuity between the groups, but not in stereoacuity. Binocular therapy may be a promising treatment of conditions affecting visual acuity, and could be applied as a supplementary method to patching for amblyopia in clinical practice. The present analysis showed that some children with amblyopia may benefit from binocular therapy. Nevertheless, larger randomised controlled clinical trials are required to confirm these findings.