A Randomized Trial of Binocular Dig Rush Game Treatment for Amblyopia in Children Aged 4 to 6 Years

Binocular treatment for amblyopia: a systematic review

PURPOSE

The treatment of unilateral amblyopia involves refractive adaptation, occlusion therapy or penalization with atropine drops. However, in recent years, the use of binocular digital therapy has shown promising results. Aim of this systematic review was to evaluate the effectiveness of binocular treatment of amblyopia compared with standard treatments or placebo therapy.

METHODS

This systematic review was conducted in accordance to PRISMA statement. Electronic literature was thoroughly searched for articles published between 2013 and May 2024, in the following electronic database; Pubmed, CENTRAL, MedlinePlus, Medline Europe, PLOS, Scopus, Clinicaltrials.gov. The review comprised randomized control trials (RCTs) including patients with unilateral amblyopia, who received binocular therapy or standard amblyopia or placebo treatment for more than two weeks and who had visual acuity assessment pre- and post-treatment. Only articles written in English were included. Risk of bias was assessed with the Rob2 tool, while study quality was evaluated with the modified Jadad scale.

RESULTS

Twenty RCTs, including 1769 patients, were incorporated into this systematic review. Twelve different types of binocular amblyopia treatments were identified and categorized into two main types. The first type involves the presentation of low-contrast images in the fellow eye, including stimuli presented only in the amblyopic eye. The second type combines this approach with complementary dichoptic deficits in the images presented to both eyes to encourage their simultaneous use.

CONCLUSION

Binocular amblyopia treatment has shown promising results in addressing unilateral anisometropic, strabismic or mixed type of amblyopia. Nevertheless, further randomized controlled trials are essential to establish the exact dosage, type and duration of binocular therapy as a standard component of amblyopia care.

Leveraging neural plasticity for the treatment of amblyopia

Amblyopia is a form of visual cortical impairment that arises from abnormal visual experience early in life. Most often, amblyopia is a unilateral visual impairment that can develop as a result of strabismus, anisometropia, or a combination of these conditions that result in discordant binocular experience. Characterized by reduced visual acuity and impaired binocular function, amblyopia places a substantial burden on the developing child. Although frontline treatment with glasses and patching can improve visual acuity, residual amblyopia remains for most children. Newer binocular-based therapies can elicit rapid recovery of visual acuity and may also improve stereoacuity in some children. Nevertheless, for both treatment modalities full recovery is elusive, recurrence of amblyopia is common, and improvements are negligible when treatment is administered at older ages. Insights derived from animal models about the factors that govern neural plasticity have been leveraged to develop innovative treatments for amblyopia. These novel therapies exhibit efficacy to promote recovery, and some are effective even at ages when conventional treatments fail to yield benefit. Approaches for enhancing visual system plasticity and promoting recovery from amblyopia include altering the balance between excitatory and inhibitory mechanisms, reversing the accumulation of proteins that inhibit plasticity, and harnessing the principles of metaplasticity. Although these therapies have exhibited promising results in animal models, their safety and ability to remediate amblyopia need to be evaluated in humans.

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, randomized controlled noninferiority trial.

SETTING

Multicenter, multinational, home treatment.

PARTICIPANTS

One hundred forty-nine children 4 to < 9 years with anisometropic, small-angle strabismic, or mixed-mechanism amblyopia were randomized to either binocular treatment (n=75) or patching (n=74).

INTERVENTIONS

The binocular 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).

MAIN OUTCOME MEASURES

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]). Other outcomes included changes in stereoacuity and binocular VA from baseline to week 16.

RESULTS

The mean improvement from baseline at week 16 in the binocular treatment group was noninferior to patching group improvement in the modified intent-to-treat (mITT) dataset (LS mean difference between groups in improvement from baseline: 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 (LS mean difference between groups in improvement from baseline: 0.05 logMAR ([95% CI; 0.007 to 0.097]). At week 16, both groups showed significant median improvement in stereoacuity, with no significant between-group difference in the magnitude of improvement in both the mITT and the PP datasets. Binocular VA was also improved in both groups (p<0.0001). 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

Binocular, eye-tracking-based amblyopia home treatment is at least as effective as patching.

Feasibility of a new 'balanced binocular viewing' treatment for unilateral amblyopia in children aged 3-8 years (BALANCE): results of a phase 2a randomised controlled feasibility trial

OBJECTIVES

This study aimed to evaluate the safety of dichoptic balanced binocular viewing (BBV) for amblyopia in children, plus feasibility, adherence, acceptability, trial methodology and clinical measures of visual function.

DESIGN

We carried out an observer-masked parallel-group phase 2a feasibility randomised controlled trial.

SETTING

Two study sites, a secondary/tertiary and a community site.

PARTICIPANTS

We enrolled 32 children aged 3-8 years with unilateral amblyopia who had completed optical adaptation where indicated. 20 children attended the 16-week exit visit (retention 63%).

INTERVENTIONS

Children were randomised to BBV (movies customised to interocular acuity difference at baseline) for 1 hour a day (active intervention) or standard management as per parental choice (part-time occlusion or atropine blurring, control). All interventions were used at home, daily for 16 weeks.

PRIMARY OUTCOME MEASURE

'VacMan suppression test' of interocular balance at 16 weeks from randomisation.

SECONDARY OUTCOME MEASURES

feasibility outcomes (recruitment and retention ratios, adherence with the allocated intervention); safety outcomes at other time points (changes in prevalence of diplopia, manifest strabismus, suppression/interocular balance on a range of tests); efficacy outcomes (clinical measures of visual function, such as best-corrected visual acuity, BCVA). Outcome measures were identical to those planned in the protocol.

RESULTS

Primary outcome: At baseline, values for the interocular balance point were higher (indicating greater suppression of the amblyopic eye) in the occlusion group than in the BBV group. These values shifted downwards on average for the occlusion group, significantly decreasing from baseline to week 16 (t8=4.49, p=0.002). Balance values did not change between baseline and week 16 for the BBV group (t9=-0.82, p=0.435). At 16 weeks, there was no statistical difference in interocular balance/suppression change over time between the two arms. The difference at follow-up between the arms, adjusted for baseline, was -0.02 (95% CI -0.28 to 0.23, p=0.87).

FEASIBILITY

We prescreened 144 records of potentially eligible children. Between 28 October 2019 and 31 July 2021, including an interruption due to the COVID-19 pandemic, 32 children were screened and randomised (recruitment rate 22%), 16 to BBV and 16 to standard treatment. 20 children attended the 16-week exit visit (retention 63%). Mean adherence with BBV as proportion of viewing time prescribed was 56.1% (SD36) at 8 and 57.9% (SD 30.2) at 16 weeks. Mean adherence with prescribed occlusion time was 90.1% (SD 19.7) at 8 and 59.2% (SD 24.8) at 16 weeks.

SECONDARY SAFETY/EFFICACY OUTCOMES

One child in the BBV arm reported transient double vision, which resolved; two reported headaches, which led to withdrawal. BCVA improved from mean 0.47 (SD0.18) logMAR at randomisation to 0.26 (0.14) with standard treatment, and from 0.55 (0.28) to 0.32 (0.26) with BBV. Outcomes at 16 weeks did not differ between treatments.

PARTICIPANT EXPERIENCE

Families were generally positive about BBV, but families found both patching and BBV difficult to integrate into family routines.

CONCLUSIONS

Recruitment rates indicate that a future phase 3 trial will require multiple sites or a longer enrolment period. Retention and adherence rates were lower than anticipated, which will influence future study designs. Dichoptic treatment may be equal to occlusion treatment in safety and efficacy; headaches may lead to discontinuation. Integration into family routines may constitute a barrier to implementation.

TRIAL REGISTRATION NUMBER

NCT03754153.

Harnessing brain plasticity to improve binocular vision in amblyopia: An evidence-based update

Amblyopia is a developmental visual disorder resulting from atypical binocular experience in early childhood that leads to abnormal visual cortex development and vision impairment. Recovery from amblyopia requires significant visual cortex neuroplasticity, i.e. the ability of the central nervous system and its synaptic connections to adapt their structure and function. There is a high level of neuroplasticity in early development and, historically, neuroplastic responses to changes in visual experience were thought to be restricted to a "critical period" in early life. However, as our review now shows, the evidence is growing that plasticity of the adult visual system can also be harnessed to improve vision in amblyopia. Amblyopia treatment involves correcting refractive error to ensure clear and equal retinal image formation in both eyes, then, if necessary, promoting the use of the amblyopic eye by hindering or reducing visual input from the better eye through patching or pharmacologic therapy. Early treatment in children can lead to visual acuity gains and the development of binocular vision in some cases; however, many children do not respond to treatment, and many adults with amblyopia have historically been untreated or undertreated. Here we review the current evidence on how dichoptic training can be used as a novel binocular therapeutic approach to facilitate visual processing of input from the amblyopic eye and can simultaneously engage both eyes in a training task that requires binocular integration. It is a novel and promising treatment for amblyopia in both children and adults.

Professional perspective and practice patterns of vision therapy in Spain

CLINICAL RELEVANCE

An analysis of the professional perspective of vision therapy (VT) by eye care professionals allows understanding the current controversies about this therapeutic option of which aspects can be improved for its correct application in clinical practice.

BACKGROUND

The aim of the current study was to analyse the perception of VT and the clinical protocols in this context followed among optometrists and ophthalmologists in Spain.

METHODS

A cross-sectional survey among Spanish optometrists and ophthalmologists. Google Forms tool was used to collect data via an online questionnaire divided into 4 sections (40 questions): consent to participate, demographic characteristics, opinion of the professional perspective of VT, and protocols. Only one submission from each email address was permitted by the survey tool.

RESULTS

A total of 889 Spanish professionals answered (age, 25-62 years): 848 optometrists (95.4%) and 41 ophthalmologists (4.6%). VT was considered as a scientifically-based procedure by 95.1% of participants, but its recognition and prestige was considered as low. The main cause reported for this was bad reputation or perception of placebo therapy (27.3%). The main indication of VT according to the surveyed professionals was convergence and/or accommodation problems (72.4%). Significant differences were found in the perception of VT among optometrists and ophthalmologists (p ≤ 0.027). A total of 45.3% of professionals reported performing VT in their current clinical practice. A combination of training sessions in office and home was regularly prescribed by 94.5% of them, but with significant variability in the duration of such sessions.

CONCLUSIONS

VT is perceived by Spanish optometrists and ophthalmologists as a therapeutic option with scientific basis, but with limited recognition and prestige, although with more negative perception among ophthalmologists. A great variability was found in the clinical protocols followed between specialists. Future efforts should be focused on creating internationally recognised evidence-based protocols for this therapeutic option.

Efficacy of Amblyopia Treatments in Children Up to Seven Years Old: A Systematic Review

Amblyopia is a neurodevelopmental disorder of the visual system that impairs the vision of millions of children worldwide. Amblyopia is best treated within the sensitive period of visual development when a child is up to seven years of age. Currently, the gold standard for early treatment of childhood amblyopia is patching, with new treatments emerging in recent years. We aim to evaluate the effectiveness of these newly developed treatments for amblyopia in children aged seven years and younger while comparing them to the current industry standard of patching. We searched online databases including PubMed, Google Scholar, and Cochrane Library for randomized controlled trials (RCTs), systematic reviews, meta-analyses, and narrative reviews relating to amblyopia treatment in children aged seven and younger. We only included articles and studies completed within the last five years and those written in the English language. After compiling a list of 297 articles, we removed duplicates, articles without an available full text, and those not relevant to our topic. Of the remaining 51 articles, we were left with 22 after reading abstracts and removing further irrelevant articles. We did a quality assessment on the remaining 22 articles and were left with 14 articles for our systematic review after removing eight low-quality articles. Of the 14 articles, we had eight RCTs, two systematic reviews, one comparative interventional study, and three narrative reviews. Seven of the articles contained data reinforcing the effectiveness of patching while comparing it to other treatment modalities. Three of the articles had data supporting spectacle correction, including a novel form called alternative flicker glass which delivers occlusion therapy via a spectacle frame with unique lenses, and ultimately deemed it at least as effective or more than patching. Data from three articles supported the use of surgery to successfully correct the angle of strabismus. Findings from five articles backed the use of pharmacologic therapy, specifically atropine when used alongside patching as a more effective alternative to patching solely. However, levodopa plus patching had no advantage over patching alone. Additionally, seven articles addressed the use of virtual reality (VR) and dichoptic therapy as prospective treatments for childhood amblyopia. VR therapy proved beneficial when used within one week after strabismus surgery. Dichoptic training was also effective in improving amblyopic-eye visual acuity when used on its own or in conjunction with spectacles. Furthermore, dichoptic movie therapy was found to be more effective than patching. Thus, we found multiple highly effective treatments for childhood amblyopia that are as effective or more than patching. Future studies should consider prescribing these treatments to larger cohorts while also performing a cost-benefit analysis for each treatment. In addition, more needs to be learned about the potential adverse side effects of these treatments, especially for pharmaceutical therapy.

Treatment of Anisometropic Amblyopia with a Dichoptic Digital Platform in Argentinian Children and Adults

PURPOSE

To evaluate and compare the results of dichoptic training in Argentinian children and adults with anisometropic amblyopia.

METHODS

Prospective non-comparative study enrolling 41 subjects with anisometropic amblyopia (age, 6-60 years old). Two groups were differentiated according to age, children (6-16 years, 24 subjects) and adults (>17 years, 17 subjects). All patients were treated with the Bynocs® platform (Kanohi Eye Pvt. Ltd, India) following a protocol of 30 sessions of training of 30 min daily 5 times a week for 6 weeks. Changes in corrected distance visual acuity (CDVA) and binocular function (BF) score with treatment were analyzed.

RESULTS

In the whole sample, CDVA in the amblyopic eye improved significantly, with a mean change of 0.30 logMAR (p < .001). Likewise, a significant improvement was also found in BF score (p < .001), with a mean change of 1.14 log units. The change achieved in CDVA was significantly correlated with the baseline CDVA in the amblyopic eye (r=-0.568, p < .001). Furthermore, no significant differences were found between age groups in the change achieved in CDVA (p = .431) and BF with therapy (p = .760).

CONCLUSIONS

Dichoptic training with the digital platform evaluated provides an effective improvement of visual acuity and binocular function in children and adults with anisometropic amblyopia.

Current Developments in the Management of Amblyopia with the Use of Perceptual Learning Techniques

Background and Objectives: Amblyopia is a neurodevelopmental disorder caused by interocular suppression of visual input, affecting visual acuity, stereopsis, contrast sensitivity, and other visual functions. Conventional treatment comprises occlusion of the sound eye. In recent years, novel therapies that deploy perceptual learning (PL) principles have been introduced. The purpose of this study is to assess the latest scientific data on this topic. Materials and Methods: For this purpose, we conducted a literature search for relevant studies published during the previous 4 years (2020-2023). Results: A plethora of visual perceptual learning protocols have been recently developed. Dichoptic video games, contrast rebalanced movies, and online perceptual training platforms are the main formats. Perceptual learning activates neuroplasticity, overcomes interocular suppression, and improves the visual impairments induced by amblyopia. Conclusions: This novel treatment is effective in both children and adults, as well as in patients non-responding to patching.

Risk of recurrence after cessation of dichoptic, binocular treatment of amblyopia

Contrast-rebalanced dichoptic games and videos have been shown to be an effective treatment for childhood amblyopia. Whether the visual acuity gains achieved with these binocular treatments are long-lasting has not been determined. In this prospective cohort study of 100 consecutive amblyopic children who improved by ≥0.2 logMAR or obtained ≤0.2 logMAR amblyopic eye visual acuity during a binocular treatment clinical trial, risk of recurrence was 24% (95% CI, 16%-35%) at up to 3 years' follow-up according to Kaplan-Meier survival analysis, which accounts for censored, truncated, and missing data. Risk of recurrence was similar among children who required additional treatment for residual amblyopia after 4-8 weeks of dichoptic treatment (n = 62 [19%]; 95% CI, 10%-34%) and those who did not (n = 38 [32%]; 95% CI, 18%-52%; P = 0.12). There was no association between recurrence and age, visual acuity at the end of binocular treatment, stereoacuity, or ocular alignment. In a secondary analysis to compare rates of recurrence with published data, risk of recurrence in the subset of children who had no additional treatment for residual amblyopia (28%) was similar to the reported recurrence after cessation of successful patching and atropine (24%) at 12 months. Children with successful binocular treatment of amblyopia require monitoring for recurrence of amblyopia.