Preliminary results from the use of the novel Interactive binocular treatment (I-BiT) system, in the treatment of strabismic and anisometropic amblyopia

Randomized Controlled Trial of Patching versus Dichoptic Stimulation Using Virtual Reality for Amblyopia Therapy

Purpose: To compare the outcomes of patching to dichoptic stimulation using virtual reality (VR) in moderate and severe amblyopia.Methods: This study was conducted on 86 subjects with unilateral anisometropic and mixed amblyopia. The subjects were randomized to the VR or patching group. The VR group received treatment using the Vivid Vision software (Vivid Vision Inc., San Francisco, USA) with each subject receiving weekly 2 h-sessions for 10 weeks. The patching group was prescribed patching for 10 weeks. Best-corrected visual acuity (BCVA) was measured using a single crowded letter in an ETDRS chart before, after 10 weeks of treatment, and after another 10 weeks of cessation of treatment. Near stereoacuity was measured using the TNO test.Results: Forty-two patients were randomized to the patching group and 44 to the VR group. The median age of the subjects was 12.0 (range 6.0 to 37.0) years. In the VR group, mean amblyopic eye BCVA showed statistically significant improvement by 0.89 line (95% confidence interval {CI}, 0.73 to 1.35 lines; p < 0.001) after 10 weeks of therapy, and after another 10 weeks of follow-up by 1.32 lines from baseline (95% CI, 1.15 to 1.7 lines; p < 0.001). Regarding the patching group, mean BCVA showed statistically significant improvement after 10 weeks by 1.38 lines (95% CI, 0.82 to 1.8 lines; p < 0.001), and after another 10 weeks by 1 line from baseline (95% CI, 0.06-0.147; 0.6 to 1.47 lines; p < 0.001). There was no significant difference between both groups at any time-point (p values >0.05). No serious adverse events were noted. Adults and severe amblyopes in the VR group showed more significant VA improvement than their counterparts in the patching group.Conclusions: Amblyopes treated using VR dichoptic treatment demonstrated statistically significant VA improvement after 10 and 20 weeks of follow-up that is comparable to patching.

A pilot non-randomized trial of smartphone-based anaglyph system for treatment of adult amblyopia through VR (Virtual Reality)

Purpose

To evaluate the effectiveness of amblyopia treatment through a smartphone-based anaglyph system by virtual reality (VR) in adult patients.

Methods

A total of 10 subjects diagnosed with anisometropic amblyopia were enrolled during the study period. Best Corrected Visual Acuity (BCVA), stereoacuity, and contrast acuity were evaluated during three visits (at presentation, 3 months and 6 months) of smartphone-based anaglyph video run in the VR mode. All the amblyogenic factors including stereopsis, color vision, and contrast acuity were compared using Friedman two-way analysis of variance. Statistical significance was considered if P < 0.05.

Results

Mean BCVA in amblyopic eye improved significantly from a logMAR value of 0.73 ± 0.64 before Virtual reality vision therapy (VRVT) to a post-training VRVT value of 0.48 ± 0.44 (P < 0.01). Mean stereoacuity changed from a value of 560.00 ± 301.58 before VRVT to a value of 263.00 ± 143.58 seconds of arc after training (VRVT) (P < 0.01). Mean accommodation changes from a value of 15.00 ± 7.40 before training or VRVT to value of 12.60 ± 6.10 cm after training (P < 0.01). Mean contrast acuity changes from a value of 1.21 ± 0.72 at presentation to a value of 1.52 ± 0.49 log unit after VRVT.

Conclusion

A smartphone-based anaglyph system using VR vision therapy appears to be an effective treatment option for amblyopia in adults.

Binocular vision therapy for the treatment of Amblyopia-A review

Amblyopia is a monocular or binocular reduction in visual acuity that results from prolonged visual deprivation in the early years of life. It is second only to refractive error as a cause of poor vision in children. The gold standard treatment of amblyopia includes patching and, less commonly, atropine penalization and filters. These therapies are aimed at improvements in the visual acuity of the amblyopic eye alone. They have compliance and psychosocial issues and gains are accrued after prolonged periods. Experimental studies have demonstrated the presence of binocular cortical communication even in amblyopes and neural plasticity in late childhood as well as adulthood. On this basis, binocular vision therapy aimed at the stimulation of both eyes rather than forced use of the amblyopic eye was developed. Such therapies involve visual tasks designed in such a way that they can be completed only by binocular viewing. These tasks vary from simple game play using red-green glasses, to engaging 3D games and movie viewing. Preliminary data suggest that binocular vision therapy has led to lasting improvements in visual acuity and can be a useful adjunct, if not replacement, to the conventional treatment of amblyopia. In this article, we aim to describe the various binocular vision therapies and review the available literature on the same.

Applications and implications for extended reality to improve binocular vision and stereopsis

Extended reality (XR) devices, including virtual reality (VR), augmented reality (AR), and mixed reality (MR) devices, are immersive technologies that can swap or merge the natural environment with virtual content (e.g., videogames, movies, or other content). Although these devices are widely used for playing videogames and other applications, they have one distinct feature that makes them potentially very useful for the measurement and treatment of binocular vision anomalies-they can deliver different content to the two eyes simultaneously. Indeed, horizontally shifting the images in the two eyes (thereby creating binocular disparity) can provide the user with a compelling percept of depth through stereopsis. Because these devices are stereoscopic, they can also be used as high-tech synoptophores, in which the images to the two eyes differ in contrast, luminance, size, position, and content for measuring and treating binocular anomalies. The inclusion of eye tracking in VR adds an additional dimension to its utility in measuring and treating binocular vision anomalies, as well as other conditions. This paper describes the essential requirements for testing and treating binocular anomalies and reviews current studies in which XR devices have been used to measure and treat binocular vision anomalies.

Amblyopia: A review of unmet needs, current treatment options, and emerging therapies

Amblyopia is a global public health issue with extensive, multifaceted impacts on vision and quality of life (QoL) for both patients and families. Geographical variation exists in the management of amblyopia, with traditional mainstay treatments, optical correction, and fellow eye occlusion most successful when implemented at an early age. In recent years, however, studies demonstrating meaningful improvements in older children and adults have challenged the concept of a complete loss of visual processing plasticity beyond the critical period of visual development, with growing evidence supporting the potential efficacy of emerging, more engaging, binocular therapies in both adults and children. Binocular approaches aim to restore deficits in amblyopia that extend beyond monocular visual acuity impairment, including binocular fusion and visuomotor skills. In view of this, incorporating outcome measures that evaluate the visual performance and functional ability of individuals with amblyopia will provide a clearer understanding of the effect of amblyopia on QoL and a more comprehensive evaluation of amblyopia therapies.

Design and assessment of amblyopia, strabismus, and myopia treatment and vision training using virtual reality

Background

Virtual reality is a relatively new intervention that has the potential to be used in the treatment of eye and vision problems. This article reviews the use of virtual reality-related interventions in amblyopia, strabismus, and myopia research.

Methods

Sources covered in the review included 48 peer-reviewed research published between January 2000 and January 2023 from five electronic databases (ACM Digital Library, IEEE Xplore, PubMed, ScienceDirect and Web of Science). To prevent any missing relevant articles, the keywords, and terms used in the search included "VR", "virtual reality", "amblyopia", "strabismus," and "myopia". Quality assessment and data extraction were performed independently by two authors to form a narrative synthesis to summarize findings from the included research.

Results

Total number of 48 references were reviewed. There were 31 studies published on amblyopia, 18 on strabismus, and 6 on myopia, with 7 studies overlapping amblyopia and strabismus. In terms of technology, smartphone-based virtual reality headset viewers were utilized more often in amblyopia research, but commercial standalone virtual reality headsets were used more frequently in myopia and strabismus-related research. The software and virtual environment were mostly developed based on vision therapy and dichoptic training paradigms.

Conclusion

It has been suggested that virtual reality technology offers a potentially effective tool for amblyopia, strabismus, and myopia studies. Nonetheless, a variety of factors, especially the virtual environment and systems employed in the data presented, must be explored before determining whether virtual reality can be effectively applied in clinical settings. This review is significant as the technology in virtual reality software and application design features have been investigated and considered for future reference.

Preliminary Study of Short-Term Visual Perceptual Training Based on Virtual Reality and Augmented Reality in Postoperative Strabismic Patients

The study aimed to explore the potential effect of short-term visual perceptual training based on virtual reality (VR) and augmented reality (AR) platforms in postoperative strabismic patients. We enrolled 236 postoperative strabismic patients, among whom 111 patients received VR-based training, and 125 patients received AR-based training. The stereoacuity of 1.5 m and dynamic stereopsis were improved by VR training; meanwhile, AR training exhibited more improvement in stereoacuity of 0.8 and 1.5 m, dynamic and coarse stereopsis. It was suggested that the visual perceptual training based on VR and AR technology can be potentially applied in postoperative strabismus treatment to promote the recovery of binocular vision.

Study protocol for a randomized controlled trial of the NEIVATECH virtual reality system to improve visual function in children with anisometropic amblyopia

BACKGROUND

Interest in developing alternative methods for the treatment of amblyopia has long been a topic of interest among clinicians and researchers, as prescribed occlusion and penalization therapies do not always provide an effective response and are associated with a high risk of recurrence and non-compliance. Here, we present the protocol of a small-scale RCT to evaluate the safety and clinical efficacy of a novel VR-based system designed to provide binocular vision training to children with anisometropic amblyopia.

METHODS

We aim to recruit a total of 60 children with anisometropic amblyopia aged 5-17 years with no previous treatment for amblyopia other than refractive correction from the pediatric ophthalmology units of the University Clinical Hospital of Valladolid and the Vithas Medimar International Hospital of Alicante. Children who meet the eligibility criteria and consent to participate will be randomly assigned to a three-month intervention group of 18 half-hour in-office therapy sessions with the NEIVATECH system (group A) or to a parallel group receiving 2 hours of conventional patching per day at home for the same period of time (group B). Assessments of visual function will be carried out before the intervention and at 1, 2 and 3 months, with changes in distance BCVA being the primary outcome measure to be considered. Patient safety, compliance, satisfaction and acceptance to treatment will also be assessed after therapy as other valuable outcome measures. In addition, a rsfMRI scan will be performed on a subgroup of 5 patients from each group at the pre-intervention visit and at the post-intervention visit to test the effects of both therapies on neural plasticity in the visual cortex.

DISCUSSION

The NEIVATECH system has been conceived as a serious game designed to provide binocular vision training to anisometropic amblyopic children by complementing the concepts of perceptual learning, dichoptic training and gamification in an immersive VR environment. We hope that this novel approach may lead to greater improvements in vision performance than those provided so far by conventional patching in anisometropic amblyopic children.

TRIAL REGISTRATION

This protocol was registered with ClinicalTrials.gov ( NCT04819386 ) on 29 March 2021.

Stereopsis Only: Validation of a Monocular Depth Cues Reduced Gamified Virtual Reality with Reaction Time Measurement

The visual depth perception is composed of monocular and binocular depth cues. Studies show that in absence of binocular depth cues the performance of visuomotor tasks like pointing to or grasping objects is limited. Thus, binocular depth cues are of great importance for motor control required in everyday life. However, binocular depth cues like retinal disparity (basis for stereopsis) might be influenced due to developmental disorders of the visual system. For example, amblyopia in which one eye's visual input is not processed leads to loss of stereopsis. The primary amblyopia treatment is occlusion of the healthy eye to force the amblyopic eye to train. However, improvements in stereopsis are poor. Therefore, binocular treatments arose that equilibrate both eyes' visual input to enable binocular vision. However, most approaches rely on divided stimuli which do not account for loss of stereopsis. We created a Virtual Reality (VR) with reduced monocular depth cues in which a stereoscopic task is shown to both eyes simultaneously, consisting of two balls jumping towards the user. One ball appears closer to the user which must be identified. To evaluate the task performance the reaction time is measured. We validated our approach with 18 participants with stereopsis under three contrast settings including one leading to monocular vision. The number of correct responses reduces from 90% under binocular vision to 52% under monocular vision corresponding to random guessing. Our results indicate that it is possible to disable monocular depth cues and create a dynamic stereoscopic task inside a VR.

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.

Binocular versus standard occlusion or blurring treatment for unilateral amblyopia in children aged three to eight years

BACKGROUND

Current treatments for amblyopia, typically patching or pharmacological blurring, have limited success. Less than two-thirds of children achieve good acuity of 0.20 logMAR in the amblyopic eye, with limited improvement of stereopsis, and poor adherence to treatment. A new approach, based on presentation of movies or computer games separately to each eye, may yield better results and improve adherence. These treatments aim to balance the input of visual information from each eye to the brain.  OBJECTIVES: To determine whether binocular treatments in children, aged three to eight years, with unilateral amblyopia result in better visual outcomes than conventional patching or pharmacological blurring treatment.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register), MEDLINE, Embase, ISRCTN, ClinicalTrials.gov, and the WHO ICTRP to 19 November 2020, with no language restrictions.

SELECTION CRITERIA

Two review authors independently screened the results of the search for relevant studies. We included randomised controlled trials (RCTs) that enrolled children between the ages of three and eight years old with unilateral amblyopia. Amblyopia was classed as present when the best-corrected visual acuity (BCVA) was worse than 0.200 logMAR in the amblyopic eye, with BCVA 0.200 logMAR or better in the fellow eye, in the presence of an amblyogenic risk factor, such as anisometropia, strabismus, or both. To be eligible, children needed to have undergone cycloplegic refraction and  ophthalmic examination, including fundal examination and optical treatment, if indicated, with stable BCVA in the amblyopic eye despite good adherence with wearing glasses. We included any type of binocular viewing intervention, on any device (e.g. computer monitors viewed with liquid-crystal display shutter glasses; hand-held screens, including mobile phones with lenticular prism overlay; or virtual reality displays). Control groups received standard amblyopia treatment, which could include patching or pharmacological blurring of the better-seeing eye. We included full-time (all waking hours) and part-time (between 1 and 12 hours a day) patching regimens. We excluded children who had received any treatment other than optical treatment; and studies with less than 8-week follow-up.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. The primary outcome of the review was the change from baseline of distance BCVA in the amblyopic eye after 16 (± 2) weeks of treatment, measured in logMAR units on an age-appropriate acuity test.

MAIN RESULTS

We identified one eligible RCT of conventional patching treatment versus novel binocular treatment, and analysed a subset of 68 children who fulfilled the age criterion of this review. We obtained data for the mean change in amblyopic eye visual acuity, adverse events (diplopia), and adherence to prescribed treatment at 8- and 16-week follow-up intervals, though no data were available for change in BCVA after 52 weeks. Risk of bias for the included study was considered to be low. The certainty of evidence for the visual acuity outcomes at 8 and 16 weeks of treatment and adherence to the study intervention was rated moderate using the GRADE criteria, downgrading by one level due to imprecision. The certainty of evidence was downgraded by two levels and rated low for the proportion of participants reporting adverse events due to the sample size.  Acuity improved in the amblyopic eye in both the binocular and patching groups following 16 weeks of treatment (improvement of -0.21 logMAR in the binocular group and -0.24 logMAR in the patching group, mean difference (MD) 0.03 logMAR (95% confidence interval (CI) -0.10 to 0.04; 63 children). This difference was non-significant and the improvements in both the binocular and patching groups are also considered clinically similar. Following 8 weeks of treatment, acuity improved in both the binocular and patching groups (improvement of -0.18 logMAR in the patching group compared to -0.16 logMAR improvement in the binocular-treatment group) (MD 0.02, 95% CI -0.04 to 0.08). Again this difference was statistically non-significant, and the differences observed between the patching and binocular groups are also clinically non-significant. No adverse event of permanent diplopia was reported. Adherence was higher in the patching group (47% of participants in the iPad group achieved over 75% compliance compared with 90% of the patching group).  Data were not available for changes in stereopsis nor for contrast sensitivity following treatment.

AUTHORS' CONCLUSIONS

Currently, there is only one RCT that offers evidence of the safety and effectiveness of binocular treatment. The authors are moderately confident that after 16 weeks of treatment, the gain in amblyopic eye acuity with binocular treatment is likely comparable to that of conventional patching treatment. However, due to the limited sample size and lack of long term (52 week) follow-up data, it is not yet possible to draw robust conclusions regarding the overall safety and sustained effectiveness of binocular treatment. Further research, using acknowledged methods of visual acuity and stereoacuity assessment with known reproducibility, is required to inform decisions about the implementation of binocular treatments for amblyopia in clinical practice, and should incorporate longer term follow-up to establish the effectiveness of binocular treatment. Randomised controlled trials should also include outcomes reported by users, adherence to prescribed treatment, and recurrence of amblyopia after cessation of treatment.

Video game treatment of amblyopia

Amblyopia is visual impairment characterized by a structurally normal eye showing significantly lower visual acuity than the fellow eye. Traditional treatment of amblyopia includes patching the good eye to force the amblyopic eye to work during normal daily activities; however, this approach is are limited by low compliance. Recently, researchers proposed a new treatment for amblyopia: video game playing. In the current review, we discuss whether video game playing can treat amblyopia, whether video game playing could better treat amblyopia than traditional treatments, and how the video game treats amblyopia and its possible mechanism. Based on results from our literature review and meta-analysis, we suggest there is strong evidence for the effectiveness of video game treatments. Moreover, multiple factors within and outside of video games could influence the treatment effect.

Applications of Extended Reality in Ophthalmology: Systematic Review

BACKGROUND

Virtual reality, augmented reality, and mixed reality make use of a variety of different software and hardware, but they share three main characteristics: immersion, presence, and interaction. The umbrella term for technologies with these characteristics is extended reality. The ability of extended reality to create environments that are otherwise impossible in the real world has practical implications in the medical discipline. In ophthalmology, virtual reality simulators have become increasingly popular as tools for surgical education. Recent developments have also explored diagnostic and therapeutic uses in ophthalmology.

OBJECTIVE

This systematic review aims to identify and investigate the utility of extended reality in ophthalmic education, diagnostics, and therapeutics.

METHODS

A literature search was conducted using PubMed, Embase, and Cochrane Register of Controlled Trials. Publications from January 1, 1956 to April 15, 2020 were included. Inclusion criteria were studies evaluating the use of extended reality in ophthalmic education, diagnostics, and therapeutics. Eligible studies were evaluated using the Oxford Centre for Evidence-Based Medicine levels of evidence. Relevant studies were also evaluated using a validity framework. Findings and relevant data from the studies were extracted, evaluated, and compared to determine the utility of extended reality in ophthalmology.

RESULTS

We identified 12,490 unique records in our literature search; 87 met final eligibility criteria, comprising studies that evaluated the use of extended reality in education (n=54), diagnostics (n=5), and therapeutics (n=28). Of these, 79 studies (91%) achieved evidence levels in the range 2b to 4, indicating poor quality. Only 2 (9%) out of 22 relevant studies addressed all 5 sources of validity evidence. In education, we found that ophthalmic surgical simulators demonstrated efficacy and validity in improving surgical performance and reducing complication rates. Ophthalmoscopy simulators demonstrated efficacy and validity evidence in improving ophthalmoscopy skills in the clinical setting. In diagnostics, studies demonstrated proof-of-concept in presenting ocular imaging data on extended reality platforms and validity in assessing the function of patients with ophthalmic diseases. In therapeutics, heads-up surgical systems had similar complication rates, procedural success rates, and outcomes in comparison with conventional ophthalmic surgery.

CONCLUSIONS

Extended reality has promising areas of application in ophthalmology, but additional high-quality comparative studies are needed to assess their roles among incumbent methods of ophthalmic education, diagnostics, and therapeutics.

Emergence of non-artificial intelligence digital health innovations in ophthalmology: A systematic review

The prominent rise of digital health in ophthalmology is evident in the current age of Industry 4.0. Despite the many facets of digital health, there has been a greater slant in interest and focus on artificial intelligence recently. Other major elements of digital health like wearables could also substantially impact patient-focused outcomes but have been relatively less explored and discussed. In this review, we comprehensively evaluate the use of non-artificial intelligence digital health tools in ophthalmology. 53 papers were included in this systematic review - 25 papers discuss virtual or augmented reality, 14 discuss mobile applications and 14 discuss wearables. Most papers focused on the use of technologies to detect or rehabilitate visual impairment, glaucoma and age-related macular degeneration. Overall, the findings on patient-focused outcomes with the adoption of these technologies are encouraging. Further validation, large-scale studies and earlier consideration of real-world barriers are warranted to enable better real-world implementation.

Virtual Reality Game Playing in Amblyopia Therapy: A Randomized Clinical Trial

PURPOSE

To compare the visual outcome of occlusion therapy with virtual reality game playing as a new therapy for children with amblyopia.

METHODS

This randomized clinical trial was performed on 50 children between 4 and 10 years old who had unilateral amblyopia. They were randomly divided into virtual reality and patching groups (n = 25 in each). The virtual reality group was trained binocularly using the virtual reality games through a head set for 1 hour per day 5 days a week for 4 weeks. Patients in the patching group occluded their non-amblyopic eyes 2, 4, and 6 hours for mild (best corrected visual acuity [BCVA] 0.2 to 0.3 logarithm of the minimum angle of resolution [logMAR]), moderate (0.3 to 0.6 logMAR), and severe (worse than 0.6 logMAR) amblyopia, respectively.

RESULTS

The mean BCVA based on logMAR units improved significantly in both groups (P < .0001), but the difference between the two groups was not significant (P = .59). BCVA based on the responded letters improved in both groups (virtual reality: P = .0001, patching: P = .001), and change in BCVA in the virtual reality group was higher than in the patching group (P = .002).

CONCLUSIONS

Virtual reality game playing was equal or superior to patching in an analysis of linear and letter BCVA, respectively. Therefore, applying this new amblyopia therapy is recommended. [J Pediatr Ophthalmol Strabismus. 2021;58(3):154-160.].

Amblyopia treatment: an evidence‐based approach to maximising treatment outcome

The basis of treatment for amblyopia (poor vision due to abnormal visual experience early in life) for 250 years has been patching of the unaffected eye for extended times to ensure a period of use of the affected eye. Over the last decade randomised controlled treatment trials have provided some evidence on how to tailor amblyopia therapy more precisely to achieve the best visual outcome with the least negative impact on the patient and the family. This review highlights the expansion of knowledge regarding treatment for amblyopia and aims to provide optometrists with a summary of research evidence to enable them to better treat amblyopia. Treatment for amblyopia is effective, as it reduces overall prevalence and severity of visual loss in this population. Correction of refractive error alone significantly improves visual acuity, sometimes to the point where further amblyopia treatment is not required. Atropine penalisation and patch occlusion are effective in treating amblyopia. Lesser amounts of occlusion or penalisation have been found to be just as effective as greater amounts. Recent evidence has highlighted that occlusion or penalisation in amblyopia treatment can create negative changes in behaviour in children and impact on family life. These complications should be considered when prescribing treatment because they can negatively affect compliance. Studies investigating the maximum age at which treatment of amblyopia can still be effective and the importance of near activities during occlusion are ongoing.

Emerging therapies for amblyopia

Traditional therapies to treat amblyopia, such as optical correction or occlusion/penalization of the non-amblyopic eye, are efficacious but are not without limitations such as poor adherence and decreased success with increasing age. Recently, there has been an interest in new amblyopia therapies, some using binocular techniques, through a variety of platforms including video games, movies, and virtual reality. Overall, available efficacy results for these treatments are highly variable.

Effects of Immersive Virtual Reality Headset Viewing on Young Children: Visuomotor Function, Postural Stability, and Motion Sickness

PURPOSE

To assess the safety of VR 3D headset (virtual reality 3-dimensional binocular-stereoscopic near-eye display) use in young children. Product safety warnings that accompany VR headsets ban their use in children under age 13 years.

DESIGN

Prospective, interventional, before-and-after study.

METHODS

Recordings were obtained in 50 children (29 boys) aged 4-10 years (mean 7.2 ± 1.8 years). Minimum binocular corrected distance visual acuity (CDVA) was 20/50 (logarithm of the minimum angle of resolution [logMAR] 0.4) and stereoacuity 800 seconds of an arc or better. A Sony PlayStation VR headset was worn for 2 sequential play sessions (of 30 minutes each) of a first-person 3D flying game (Eagle Flight) requiring head movement to control flight direction (pitch, yaw, and roll axes). Baseline testing preceded VR exposure, and each VR session was followed by post-VR testing of binocular CDVA, refractive error, binocular eye alignment (strabismus), stereoacuity, and postural stability (imbalance). Visually induced motion sickness was probed using the Simulator Sickness Questionnaire modified for pediatric use (Peds SSQ). Visual-vestibulo-ocular reflex (V-VOR) adaptation was also tested pre- vs post-trial in 5 of the children. Safety was gauged as a decline or change from baseline in any visuomotor measure.

RESULTS

Forty-six of 50 children (94%) completed both VR play sessions with no significant change from baseline in measures of binocular CDVA (P = .89), refractive error (P = .36), binocular eye alignment (P = .90), or stereoacuity (P = .45). Postural stability degraded an average 9% from baseline after 60 minutes of VR exposure (P = .06). Peds SSQ scores increased a mean 4.7%-comparing pretrial to post-trial-for each of 4 symptom categories: eye discomfort (P = .02), head/neck discomfort (P = .03), fatigue (P = .03), and motion sickness (P = .01). None of the children who finished both trial sessions (94%) asked to end the play, and the majority were disappointed when play was halted. V-VOR gain remained unaltered in the 5 children tested. Three children (6% of participants) discontinued the trial during the first 10 minutes of the first session of VR play, 2 girls (aged 5 and 6 years) and 1 boy (aged 7 years). The girls reported discomfort consistent with mild motion sickness; the boy said he was bored and the headset was uncomfortable. No child manifested aftereffects ("flashbacks") in the days following the VR exposure.

CONCLUSION

Young children tolerate fully immersive 3D virtual reality game play without noteworthy effects on visuomotor functions. VR play did not induce significant post-VR postural instability or maladaption of the vestibulo-ocular reflex. The prevalence of discomfort and aftereffects may be less than that reported for adults.

The Potential of Virtual Reality for Inducing Neuroplasticity in Children with Amblyopia

In recent years, virtual reality (VR) has emerged as a new safe and effective tool for neurorehabilitation of different childhood and adulthood conditions. VR-based therapies can induce cortical reorganization and promote the activation of different neuronal connections over a wide range of ages, leading to contrasted improvements in motor and functional skills. The use of VR for the visual rehabilitation in amblyopia has been investigated in the last years, with the potential of using serious games combining perceptual learning and dichoptic stimulation. This combination of technologies allows the clinician to measure, treat, and control changes in interocular suppression, which is one of the factors leading to cortical alterations in amblyopia. Several clinical researches on this issue have been conducted, showing the potential of promoting visual acuity, contrast sensitivity, and stereopsis improvement. Indeed, several systems have been evaluated for amblyopia treatment including the use of different commercially available types of head mounted displays (HMDs). These HMDs are mostly well tolerated by patients during short exposures and do not cause significant long-term side effects, although their use has been occasionally associated with some visual discomfort and other complications in certain types of subjects. More studies are needed to confirm these promising therapies in controlled randomized clinical trials, with special emphasis on the definition of the most adequate planning for obtaining an effective recovery of the visual and binocular function.

Binocular Treatment of Amblyopia: A Report by the American Academy of Ophthalmology

PURPOSE

To review the published literature assessing the efficacy of binocular therapy for the treatment of amblyopia compared with standard treatments.

METHODS

Literature searches with no date restrictions and limited to the English language were conducted in January 2018 and updated in April 2019 in the PubMed database and the Cochrane Library database with no restrictions. The search yielded 286 citations, and the full text of 50 articles was reviewed. Twenty articles met the inclusion criteria for this assessment and were assigned a level of evidence rating by the panel methodologist. Six studies were rated level I, 1 study was rated level II, and 13 studies were rated level III because of the impact on the development and popularization of this technology.

RESULTS

Two of the level I and II studies reviewed described a significant improvement in visual acuity in the binocular group versus standard patching standard treatment (the total number of patients in these 2 studies was 147). However, the 5 studies that failed to show a visual improvement from binocular therapy compared with standard treatments were larger and more rigorously designed (the total number of patients in these 5 studies was 813). Level I and II studies also failed to show a significant improvement over baseline in sensory status, including depth of suppression and stereopsis of those treated with binocular therapy. Several smaller level III case series (total number of patients in these 13 studies was 163) revealed more promising results than the binocular treatments studied in the level I and II studies, especially using treatments that are more engaging and are associated with better compliance.

CONCLUSIONS

There is no level I evidence to support the use of binocular treatment as a substitute for current therapies for amblyopia (including patching and optical treatment). Furthermore, 2 large randomized controlled trials showed inferior performance compared with standard patching treatment. On the basis of this review of the published literature, binocular therapy cannot be recommended as a replacement for standard amblyopia therapy. However, more research is needed to determine the potential benefits of proposed binocular treatments in the future.

Contribution of Short-Time Occlusion of the Amblyopic Eye to a Passive Dichoptic Video Treatment for Amblyopia beyond the Critical Period

Dichoptic movie viewing has been shown to significantly improve visual acuity in amblyopia in children. Moreover, short-term occlusion of the amblyopic eye can transiently increase its contribution to binocular fusion in adults. In this study, we first asked whether dichoptic movie viewing could improve the visual function of amblyopic subjects beyond the critical period. Secondly, we tested if this effect could be enhanced by short-term monocular occlusion of the amblyopic eye. 17 subjects presenting stable functional amblyopia participated in this study. 10 subjects followed 6 sessions of 1.5 hour of dichoptic movie viewing (nonpatched group), and 7 subjects, prior to each of these sessions, had to wear an occluding patch over the amblyopic eye for two hours (patched group). Best-corrected visual acuity, monocular contrast sensitivity, interocular balance, and stereoacuity were measured before and after the training. For the nonpatched group, mean amblyopic eye visual acuity significantly improved from 0.54 to 0.46 logMAR (p < 0.05). For the patched group, mean amblyopic eye visual acuity significantly improved from 0.62 to 0.43 logMAR (p < 0.05). Stereoacuity improved significantly when the data of both groups were combined. No significant improvement was observed for the other visual functions tested. Our training procedure combines modern video technologies and recent fundamental findings in human plasticity: (i) long-term plasticity induced by dichoptic movie viewing and (ii) short-term adaptation induced by temporary monocular occlusion. This passive dichoptic movie training approach is shown to significantly improve visual acuity of subjects beyond the critical period. The addition of a short-term monocular occlusion to the dichoptic training shows promising trends but was not significant for the sample size used here. The passive movie approach combined with interocular contrast balancing even over such a short period as 2 weeks has potential as a clinical therapy to treat amblyopia in older children and adults.

Comparison between patching and interactive binocular treatment in amblyopia: A randomized clinical trial

Purpose

To compare the effect of amblyopia therapy on cases who received interactive binocular treatment (I-BiT™) with those who received standard patching of the dominant eye with placebo I-BiT™.

Methods

In this randomized clinical trial, 38 unilateral amblyopic children (3–10 years old) were studied. All unilateral amblyopic children who had best corrected visual acuity (BCVA) worse than 0.30 logMAR or a difference of two Snellen lines of BCVA between their two eyes were included, and children who did not complete at least 75% of amblyopia treatment were excluded from this study. Eventually, a total of 19 and 21 subjects were included in case and control groups, respectively. Cases played I-BiT™ games, while controls had standard patch therapy and played with placebo I-BiT™ games, both for one month. All subjects were examined at baseline and after one-month therapy.

Results

BCVA improved significantly in both groups after one-month treatment (case: P = 0.003, control: P < 0.001), while in comparison with each other, there was not any difference between them (P = 0.52). Although stereopsis improved in the case (P < 0.001) and control (P < 0.001), there was no significant difference between them pre and post-therapy. Our children played games for about 6 h total during one month in both groups, and their compliance was 87.5% and 76% in cases and controls, respectively. Two children were excluded due to their lower compliance of playing I-BiT™ games (n = 38).

Conclusions

I-BiT™ game and patching with placebo game had similar BCVA improvement in amblyopic children after one-month treatment. It is suggested to conduct further randomized clinical trials with a larger sample size and longer duration of study and assessment of its recurrence.

Clinical investigation plan for the use of interactive binocular treatment (I-BiT) for the management of anisometropic, strabismic and mixed amblyopia in children aged 3.5-12 years: a randomised controlled trial

Background

Amblyopia (lazy eye) affects the vision of approximately 2% of all children. Traditional treatment consists of wearing a patch over their ‘good’ eye for a number of hours daily, over several months. This treatment is unpopular and compliance is often low. Therefore, results can be poor. I-BiT is a system, based on stereo technology using shutter glasses, designed to treat amblyopia using dichoptic stimulation. This trial uses a redesigned system for home use and includes eye-tracking capability.

Methods/design

This is a randomised controlled trial involving three groups of 40 patients each, aged between 3.5 and 12 years, with a diagnosis of (1) anisometropic amblyopia, (2) mixed or strabismic amblyopia prior to strabismic surgery and (3) mixed or strabismic amblyopia who have just undergone strabismus surgery. They will be randomised in a 1:1 ratio between I-BiT and control and will receive treatment, at home over a 6-week period. Their visual acuity will be assessed independently at baseline, mid-treatment (week 3), at the end of treatment (week 6) and, for those receiving the active I-BiT treatment, 4 weeks after completing treatment (week 10).

The primary endpoint will be the change in visual acuity from baseline to the end of treatment. Secondary endpoints will be additional visual acuity measures, patient acceptability, compliance and the incidence of adverse events.

Discussion

This is a randomised controlled trial using the redesigned I-BiT™ system to determine if this is a feasible treatment strategy for the management of anisometropic, strabismic and mixed amblyopia.

Trial registration

ISRCTN Number/Clinical trials.gov, ID: NCT02810847. Registered on 23 June 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3523-0) contains supplementary material, which is available to authorized users.

New advances in amblyopia therapy I: binocular therapies and pharmacologic augmentation

Amblyopia therapy options have traditionally been limited to penalisation of the non-amblyopic eye with either patching or pharmaceutical penalisation. Solid evidence, mostly from the Pediatric Eye Disease Investigator Group, has validated both number of hours a day of patching and days per week of atropine use. The use of glasses alone has also been established as a good first-line therapy for both anisometropic and strabismic amblyopia. Unfortunately, visual acuity equalisation or even improvement is not always attainable with these methods. Additionally, non-compliance with prescribed therapies contributes to treatment failures, with data supporting difficulty adhering to full treatment sessions. Interest in alternative therapies for amblyopia treatment has long been a topic of interest among researchers and clinicians alike. Incorporating new technology with an understanding of the biological basis of amblyopia has led to enthusiasm for binocular treatment of amblyopia. Early work on perceptual learning as well as more recent enthusiasm for iPad-based dichoptic training have each generated interesting and promising data for vision improvement in amblyopes. Use of pharmaceutical augmentation of traditional therapies has also been investigated. Several different drugs with unique mechanisms of action are thought to be able to neurosensitise the brain and enhance responsiveness to amblyopia therapy. No new treatment has emerged from currently available evidence as superior to the traditional therapies in common practice today. But ongoing investigation into the use of both new technology and the understanding of the neural basis of amblyopia promises alternate or perhaps better cures in the future.

An action video game for the treatment of amblyopia in children: A feasibility study

The gold-standard treatment for childhood amblyopia remains patching or penalizing the fellow eye, resulting in an average of about a one line (0.1 logMAR) improvement in visual acuity following ≈120 h of patching in children 3-8 years old. However, compliance with patching and other treatment options is often poor. In contrast, fast-paced action video games can be highly engaging, and have been shown to yield broad-based improvements in vision and attention in adult amblyopia. Here, we pilot-tested a custom-made action video game to treat children with amblyopia. Twenty-one (n = 21) children (mean age 9.95 ± 3.14 [se]) with unilateral amblyopia (n = 12 anisometropic and n = 9 strabismic) completed 20 h of game play either monocularly, with the fellow eye patched (n = 11), or dichoptically, with reduced contrast to the fellow eye (n = 10). Participants were assessed for visual acuity (VA), stereo acuity and reading speed at baseline, and following 10 and 20 h of play. Additional exploratory analyses examined improvements after 6-10 weeks of completion of training (follow-up). Following 20 h of training, VA improved, on average, by 0.14 logMAR (≈38%) for the dichoptic group and by 0.06 logMAR (≈15%) for the monocular group. Similarly, stereoacuity improved by 0.07 log arcsec (≈17%) following dichoptic training, and by 0.06 log arcsec (≈15%) following monocular training. Across both treatment groups, 7 of the 12 individuals with anisometropic amblyopia showed improvement in stereoacuity, whereas only 1 of the 9 strabismic individuals improved. Most improvements were largely retained at follow-up. Our feasibility study therefore suggests that the action video game approach may be used as an effective adjunct treatment for amblyopia in children, achieving results similar to those of the gold-standard treatment in shorter duration.

Television Video Games in the Treatment of Amblyopia in Children Aged 4-7 Years

AIM

To investigate the role of television video games in childhood amblyopia treatment.

METHOD

This prospective, randomized, interventional study included 40 patients between 4-7 years of age, with unilateral amblyopia (visual acuity in amblyopic eye between 1-0.6 LogMAR equivalents) attending the squint clinic at a tertiary eye hospital. All patients were prescribed optimal spectacle correction and occlusion therapy, i.e. full time patching according to patient's age, was initiated after six weeks.; full-time patching according to patient's age was initiated after 6 weeks. Subjects were randomly divided into two groups of 20 each. Patients in the first group, Group A (control), were prescribed patching alone. Patients in the second group, Group B (study), were made to play action video games, with the help of a commercial television set, along with patching. They attended 12 half-hour sessions each, at weekly intervals. Follow-up assessments included best corrected visual acuity (BCVA) (both distance and near) and stereoacuity measurements at 3, 6, 9, and 12 weeks.

RESULTS

The mean age of patients was 6.03 ± 1.14 years. The distance BCVA in the amblyopic eye showed a significant improvement at final follow-up (12 weeks) in both groups: from 0.84 ± 0.19 to 0.55 ± 0.21 LogMAReq in Group A and 0.89 ± 0.16 to 0.46 ± 0.22 LogMAReq in Group B. However, improvement in BCVA was significantly better in group B at all visits (P=0.002, 12 weeks). The study group also had a significantly better outcome in terms near visual acuity improvement (P = 0.006, 12 weeks). There was also greater stereoacuity improvement in group B, with 7 patients improving to 100 secs of arc or better.

CONCLUSION

Video games supplemental to occlusion may be considered favorable for visual development in amblyopic children, and the study encourages further research on this subject.

Use of video games for the treatment of amblyopia

PURPOSE OF REVIEW

To review the literature up to recent for the use of videos, videogames and dichoptic stimulation as a treatment for amblyopia.

RECENT FINDINGS

There have been three strategies explored. The first is to use videos and videogames monocularly with the normal eye covered. The second is dichoptic stimulation with a common background presented to both eyes and an enriched foreground to the amblyopic eye. The third are games specifically designed to generate stereopsis. Most work has focused on the second of these approaches but both of the first two approaches seem to give a similar improvement of 0.1-0.2 logMAR. One large randomized control trial (RCT) has published showing that dichoptic stimulation is not inferior to patching but no evidence that it was superior. It also showed that video games have their own compliance problems and a second smaller RCT did suggest that videogames, with a game designed by a gaming company, was superior. Most of the work done has had methodological issues and should be considered exploratory rather than definitive.

SUMMARY

Dichoptic stimulation is a viable treatment option for the treatment of amblyopia. The first trial results have shown results that are not superior to patching but they are not without methodological issues. There is sufficient encouragement to justify further research in this area.

The role of Interactive Binocular Treatment system in amblyopia therapy

Purpose

To determine the role of Interactive Binocular Treatment (I-BiT™) as a complementary method of patching in amblyopia therapy.

Methods

In this randomized clinical trial study, 50 unilateral amblyopic children (25 male/25 female) between 3 and 10 years with either best corrected visual acuity (BCVA) ≤20/30 in the amblyopic eye or a difference of BCVA ≥ 2 lines between the two eyes were included. They were randomly classified into the case and control groups (25 in each). Patching was recommended in both groups, and cases also received I-BiT™. Cases were asked to play I-BiT™ games through appropriate glasses with conjugate colored filters. Moving and fixed targets were shown to the amblyopic and non-amblyopic eyes, respectively. Playing games was continued 20 min in each session for 5 days a week within one month (total time: 6.6 h). Patching was continued for one month more in both groups to evaluate the continuous effect of I-BiT™. BCVA was measured at baseline, one month after beginning I-BiT™, and one month after cessation of I-BiT™.

Results

BCVA of amblyopic eyes in cases and controls were 0.34 ± 0.14 and 0.33 ± 0.17LogMAR at baseline which improved to 0.17 ± 0.14 and 0.26 ± 0.17 at one month, respectively. The difference was significant in each group (p < 0.001 for cases and p = 0.024 for controls) with more improvement in the case group (p < 0.001). One month after cessation of I-BiT™, BCVA difference between the two groups was not statistically significant. There was no case with recurrence of amblyopia.

Conclusion

Based on our results, I-BiT™ seems to be effective in amblyopia therapy accompanied with patching. We recommend comparing I-BiT™ alone with patching in further studies.

ClinicalTrials.gov Identifier: NCT02740725.

Randomised controlled trial of video clips and interactive games to improve vision in children with amblyopia using the I-BiT system

Background

Traditional treatment of amblyopia involves either wearing a patch or atropine penalisation of the better eye. A new treatment is being developed on the basis of virtual reality technology allowing either DVD footage or computer games which present a common background to both eyes and the foreground, containing the imagery of interest, only to the amblyopic eye.

Methods

A randomised control trial was performed on patients with amblyopia aged 4–8 years with three arms. All three arms had dichoptic stimulation using shutter glass technology. One arm had DVD footage shown to the amblyopic eye and common background to both, the second used a modified shooter game, Nux, with sprite and targets presented to the amblyopic eye (and background to both) while the third arm had both background and foreground presented to both eyes (non-interactive binocular treatment (non-I-BiT) games).

Results

Seventy-five patients were randomised; 67 were residual amblyopes and 70 had an associated strabismus. The visual acuity improved in all three arms by approximately 0.07 logMAR in the amblyopic eye at 6 weeks. There was no difference between I-BiT DVD and non-I-BiT games compared with I-BiT games (stated primary outcome) in terms of gain in vision.

Conclusions

There was a modest vision improvement in all three arms. Treatment was well tolerated and safe. There was no difference between the three treatments in terms of primary stated outcomes but treatment duration was short and the high proportion of previously treated amblyopia and strabismic amblyopia disadvantaged dichoptic stimulation treatment.

Trial registration number

NCT01702727, results.

Binocular versus standard occlusion or blurring treatment for unilateral amblyopia in children aged three to eight years

BACKGROUND

Current treatments for amblyopia in children, occlusion and pharmacological blurring, have had limited success, with less than two-thirds of children achieving good visual acuity of at least 0.20 logMAR in the amblyopic eye, limited improvement of stereopsis, and poor compliance. A new treatment approach, based on the dichoptic presentation of movies or computer games (images presented separately to each eye), may yield better results, as it aims to balance the input of visual information from each eye to the brain. Compliance may also improve with these more child-friendly treatment procedures.

OBJECTIVES

To determine whether binocular treatments in children aged three to eight years with unilateral amblyopia result in better visual outcomes than conventional occlusion or pharmacological blurring treatment.

SEARCH METHODS

We searched the Cochrane Eyes and Vision Group Trials Register (last date of searches: 14 April 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 3), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to April 2015), EMBASE (January 1980 to April 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials.

SELECTION CRITERIA

Two review authors independently screened the results of the search in order to identify studies that met the inclusion criteria of the review: randomised controlled trials (RCTs) that enrolled participants between the ages of three and eight years old with unilateral amblyopia, defined as best-corrected visual acuity (BCVA) worse than 0.200 logMAR in the amblyopic eye, and BCVA 0.200 logMAR or better in the fellow eye, in the presence of an amblyogenic risk factor such as anisometropia, strabismus, or both. Prior to enrolment, participants were to have undergone a cycloplegic refraction and comprehensive ophthalmic examination including fundal examination. In addition, participants had to have completed a period of optical treatment, if indicated, and BCVA in the amblyopic eye had to remain unchanged on two consecutive assessments despite reportedly good compliance with glasses wearing. Participants were not to have received any treatment other than optical treatment prior to enrolment. We planned to include any type of binocular viewing intervention; these could be delivered on different devices including computer monitors viewed with LCD shutter glasses or hand-held screens including mobile phone screens with lenticular prism overlay. Control groups were to have received standard amblyopia treatment; this could include occlusion or pharmacological blurring of the better-seeing eye. We planned to include full-time (all waking hours) and part-time (between 1 and 12 hours a day) occlusion regimens.

DATA COLLECTION AND ANALYSIS

We planned to use standard methodological procedures expected by The Cochrane Collaboration. We had planned to meta-analyse the primary outcome, that is mean distance BCVA in the amblyopic eye at 12 months after the cessation of treatment.

MAIN RESULTS

We could identify no RCTs in this subject area.

AUTHORS' CONCLUSIONS

Further research is required to allow decisions about implementation of binocular treatments for amblyopia in clinical practice. Currently there are no clinical trials offering standardised evidence of the safety and effectiveness of binocular treatments, but results from non-controlled cohort studies are encouraging. Future research should be conducted in the form of RCTs, using acknowledged methods of visual acuity and stereoacuity assessment with known reproducibility. Other important outcome measures include outcomes reported by users, compliance with treatment, and recurrence of amblyopia after cessation of treatment.

Neuroimaging of amblyopia and binocular vision: a review

Amblyopia is a cerebral visual impairment considered to derive from abnormal visual experience (e.g., strabismus, anisometropia). Amblyopia, first considered as a monocular disorder, is now often seen as a primarily binocular disorder resulting in more and more studies examining the binocular deficits in the patients. The neural mechanisms of amblyopia are not completely understood even though they have been investigated with electrophysiological recordings in animal models and more recently with neuroimaging techniques in humans. In this review, we summarize the current knowledge about the brain regions that underlie the visual deficits associated with amblyopia with a focus on binocular vision using functional magnetic resonance imaging. The first studies focused on abnormal responses in the primary and secondary visual areas whereas recent evidence shows that there are also deficits at higher levels of the visual pathways within the parieto-occipital and temporal cortices. These higher level areas are part of the cortical network involved in 3D vision from binocular cues. Therefore, reduced responses in these areas could be related to the impaired binocular vision in amblyopic patients. Promising new binocular treatments might at least partially correct the activation in these areas. Future neuroimaging experiments could help to characterize the brain response changes associated with these treatments and help devise them.

A binocular iPad treatment for amblyopic children

PURPOSE

Monocular amblyopia treatment (patching or penalization) does not always result in 6/6 vision and amblyopia often recurs. As amblyopia arises from abnormal binocular visual experience, we evaluated the effectiveness of a novel home-based binocular amblyopia treatment.

METHODS

Children (4-12 y) wore anaglyphic glasses to play binocular games on an iPad platform for 4 h/w for 4 weeks. The first 25 children were assigned to sham games and then 50 children to binocular games. Children in the binocular group had the option of participating for an additional 4 weeks. Compliance was monitored with calendars and tracking fellow eye contrast settings. About half of the children in each group were also treated with patching at a different time of day. Best-corrected visual acuity, suppression, and stereoacuity were measured at baseline, at the 4- and 8-week outcome visits, and 3 months after cessation of treatment.

RESULTS

Mean (±SE) visual acuity improved in the binocular group from 0.47±0.03 logMAR at baseline to 0.39±0.03 logMAR at 4 weeks (P<0.001); there was no significant change for the sham group. The effect of binocular games on visual acuity did not differ for children who were patched vs those who were not. The median stereoacuity remained unchanged in both groups. An additional 4 weeks of treatment did not yield additional visual acuity improvement. Visual acuity improvements were maintained for 3 months after the cessation of treatment.

CONCLUSIONS

Binocular iPad treatment rapidly improved visual acuity, and visual acuity was stable for at least 3 months following the cessation of treatment.

Amblyopia treatment strategies and new drug therapies

Amblyopia is a unilateral or bilateral reduction of visual acuity secondary to abnormal visual experience during early childhood. It is one of the most common causes of vision loss and monocular blindness and is commonly associated with strabismus, anisometropia, and visual deprivation (in particular congenital cataract and ptosis). It is clinically defined as a two-line difference of best-corrected visual acuity between the eyes. The purpose of this study was to understand the neural mechanisms of amblyopia and summarize the current therapeutic strategies. In particular, the authors focused on the concept of brain plasticity and its implication for new treatment strategies for children and adults with amblyopia.

Interactive binocular treatment (I-BiT) for amblyopia: results of a pilot study of 3D shutter glasses system

PURPOSE

A computer-based interactive binocular treatment system (I-BiT) for amblyopia has been developed, which utilises commercially available 3D 'shutter glasses'. The purpose of this pilot study was to report the effect of treatment on visual acuity (VA) in children with amblyopia.

METHODS

Thirty minutes of I-BiT treatment was given once weekly for 6 weeks. Treatment sessions consisted of playing a computer game and watching a DVD through the I-BiT system. VA was assessed at baseline, mid-treatment, at the end of treatment, and at 4 weeks post treatment. Standard summary statistics and an exploratory one-way analysis of variance (ANOVA) were performed.

RESULTS

Ten patients were enrolled with strabismic, anisometropic, or mixed amblyopia. The mean age was 5.4 years. Nine patients (90%) completed the full course of I-BiT treatment with a mean improvement of 0.18 (SD=0.143). Six out of nine patients (67%) who completed the treatment showed a clinically significant improvement of 0.125 LogMAR units or more at follow-up. The exploratory one-way ANOVA showed an overall effect over time (F=7.95, P=0.01). No adverse effects were reported.

CONCLUSION

This small, uncontrolled study has shown VA gains with 3 hours of I-BiT treatment. Although it is recognised that this pilot study had significant limitations-it was unblinded, uncontrolled, and too small to permit formal statistical analysis-these results suggest that further investigation of I-BiT treatment is worthwhile.

Evaluation and development of a novel binocular treatment (I-BiT™) system using video clips and interactive games to improve vision in children with amblyopia ('lazy eye'): study protocol for a randomised controlled trial

Background

Amblyopia (lazy eye) affects the vision of approximately 2% of all children. Traditional treatment consists of wearing a patch over their ‘good’ eye for a number of hours daily, over several months. This treatment is unpopular and compliance is often low. Therefore results can be poor. A novel binocular treatment which uses 3D technology to present specially developed computer games and video footage (I-BiT™) has been studied in a small group of patients and has shown positive results over a short period of time. The system is therefore now being examined in a randomised clinical trial.

Methods/design

Seventy-five patients aged between 4 and 8 years with a diagnosis of amblyopia will be randomised to one of three treatments with a ratio of 1:1:1 - I-BiT™ game, non-I-BiT™ game, and I-BiT™ DVD. They will be treated for 30 minutes once weekly for 6 weeks. Their visual acuity will be assessed independently at baseline, mid-treatment (week 3), at the end of treatment (week 6) and 4 weeks after completing treatment (week 10). The primary endpoint will be the change in visual acuity from baseline to the end of treatment. Secondary endpoints will be additional visual acuity measures, patient acceptability, compliance and the incidence of adverse events.

Discussion

This is the first randomised controlled trial using the I-BiT™ system. The results will determine if the I-BiT™ system is effective in the treatment of amblyopia and will also determine the optimal treatment for future development.

Trial registration

ClinicalTrials.gov identifier: NCT01702727

Effects of digesting chondroitin sulfate proteoglycans on plasticity in cat primary visual cortex

Monocular deprivation (MD) during a critical period of postnatal development produces significant changes in the anatomy and physiology of the visual cortex, and the deprived eye becomes amblyopic. Extracellular matrix molecules have a major role in restricting plasticity such that the ability to recover from MD decreases with age. Chondroitin sulfate proteoglycans (CSPGs) act as barriers to cell migration and axon growth. Previous studies showing that degradation of CSPGs by the bacterial enzyme chondroitinase can restore plasticity in the adult rat visual cortex suggest a potential treatment for amblyopia. Here MD was imposed in cats from the start of the critical period until 3.5 months of age. The deprived eye was reopened, the functional architecture of the visual cortex was assessed by optical imaging of intrinsic signals, and chondroitinase was injected into one hemisphere. Imaging was repeated 1 and 2 weeks postinjection, and visually evoked potentials (VEPs) and single-cell activity were recorded. Immunohistochemistry showed that digestion of CSPGs had been successful. After 2 weeks of binocular exposure, some recovery of deprived-eye responses occurred when chondroitinase had been injected into the hemisphere contralateral to that eye; when injected into the ipsilateral hemisphere, no recovery was seen. Deprived-eye VEPs were no larger in the injected hemisphere than in the opposite hemisphere. The small number of neurons dominated by the deprived eye exhibited poor tuning characteristics. These results suggest that despite structural effects of chondroitinase in adult cat V1, plasticity was not sufficiently restored to enable significant functional recovery of the deprived eye.

Quantitative measurement of interocular suppression in children with amblyopia

In this study we explored the possibility of using a dichoptic global motion technique to measure interocular suppression in children with amblyopia. We compared children (5-16 years old) with unilateral anisometropic and/or strabismic amblyopia to age-matched control children. Under dichoptic viewing conditions, contrast interference thresholds were determined with a global motion direction-discrimination task. Using virtual reality goggles, high contrast signal dots were presented to the amblyopic eye, while low contrast noise dots were presented to the non-amblyopic fellow eye. The contrast of the noise dots was increased until discrimination of the motion direction of the signal dots reached chance performance. Contrast interference thresholds were significantly lower in the strabismic group than in the anisometropic and control group. Our results suggest that interocular suppression is stronger in strabismic than in anisometropic amblyopia.

Can perceptual learning be used to treat amblyopia beyond the critical period of visual development?

BACKGROUND

Amblyopia presents early in childhood and affects approximately 3% of western populations. The monocular visual acuity loss is conventionally treated during the 'critical periods' of visual development by occluding or penalising the fellow eye to encourage use of the amblyopic eye. Despite the measurable success of this approach in many children, substantial numbers of people still suffer with amblyopia later in life because either they were never diagnosed in childhood, did not respond to the original treatment, the amblyopia was only partially remediated, or their acuity loss returned after cessation of treatment.

PURPOSE

In this review, we consider whether the visual deficits of this largely overlooked amblyopic group are amenable to conventional and innovative therapeutic interventions later in life, well beyond the age at which treatment is thought to be effective.

RECENT FINDINGS

There is a considerable body of evidence that residual plasticity is present in the adult visual brain and this can be harnessed to improve function in adults with amblyopia. Perceptual training protocols have been developed to optimise visual gains in this clinical population. Results thus far are extremely encouraging; marked visual improvements have been demonstrated, the perceptual benefits transfer to new visual tasks and appear to be relatively enduring. The essential ingredients of perceptual training protocols are being incorporated into video game formats, facilitating home-based interventions.

SUMMARY

Many studies support perceptual training as a tool for improving vision in amblyopes beyond the critical period. Should this novel form of treatment stand up to the scrutiny of a randomised controlled trial, clinicians may need to re-evaluate their therapeutic approach to adults with amblyopia.

A computer-based anaglyphic system for the treatment of amblyopia

PURPOSE

Virtual reality (VR)-based treatment has been introduced as a potential option for amblyopia management, presumably without involving the problems of occlusion and penalization, including variable and unsatisfactory outcomes, long duration of treatment, poor compliance, psychological impact, and complications. However, VR-based treatment is costly and not accessible for most children. This paper introduces a method that encompasses the advantages of VR-based treatment at a lower cost.

METHODS

The presented system consists of a pair of glasses with two color filters and software for use on a personal computer. The software is designed such that some active graphic components can only be seen by the amblyopic eye and are filtered out for the other eye. Some components would be seen by both to encourage fusion. The result is that the patient must use both eyes, and specifically the amblyopic eye, to play the games.

RESULTS

A prototype of the system, the ABG InSight, was found capable of successfully filtering out elements of a certain color and therefore, could prove to be a viable alternative to VR-based treatment for amblyopia.

CONCLUSION

The anaglyphic system maintains most of the advantages of VR-based systems, but is less costly and highly accessible. It fulfills the means that VR-based systems are designed to achieve, and warrants further investigation.

Can human amblyopia be treated in adulthood?

Amblyopia is a common visual disorder that results in a spatial acuity deficit in the affected eye. Orthodox treatment is to occlude the unaffected eye for lengthy periods, largely determined by the severity of the visual deficit at diagnosis. Although this treatment is not without its problems (poor compliance, potential to reduce binocular function, etc) it is effective in many children with moderate to severe amblyopia. Diagnosis and initiation of treatment early in life are thought to be critical to the success of this form of therapy. Occlusion is rarely undertaken in older children (more than 10 years old) as the visual benefits are considered to be marginal. Therefore, in subjects where occlusion is not effective or those missed by mass screening programs, there is no alternative therapy available later in life. More recently, burgeoning evidence has begun to reveal previously unrecognized levels of residual neural plasticity in the adult brain and scientists have developed new genetic, pharmacological, and behavioral interventions to activate these latent mechanisms in order to harness their potential for visual recovery. Prominent amongst these is the concept of perceptual learning--the fact that repeatedly practicing a challenging visual task leads to substantial and enduring improvements in visual performance over time. In the normal visual system the improvements are highly specific to the attributes of the trained stimulus. However, in the amblyopic visual system, learned improvements have been shown to generalize to novel tasks. In this paper we ask whether amblyopic deficits can be reduced in adulthood and explore the pattern of transfer of learned improvements. We also show that developing training protocols that target the deficit in stereo acuity allows the recovery of normal stereo function even in adulthood. This information will help guide further development of learning-based interventions in this clinical group.

Randomised controlled trial of intermittent photic stimulation for treating amblyopia in older children and adults

The treatment of amblyopia is reviewed and it is noted that in addition to conventional 'passive treatment' in children with occlusion, it has been argued that 'active treatment' may be effective in older children and adults. Intermittent photic stimulation (IPS) is one such active treatment. In Study 1, we report a clinical audit of 21 patients treated with IPS, which demonstrated that the maximum improvement is reached after 6 half hour sessions. Study 2 is a double-masked randomised controlled trial comparing IPS with a control treatment in 30 participants aged 10-57 years. Using a sensitive staircase measure of visual acuity (VA), the IPS group improved by about one line (p = 0.0053). The mean improvement was significantly greater (unpaired t-test, p = 0.022) in the IPS group (mean 0.096; S.E.M. 0.029) than in the control group (mean 0.019; S.E.M. 0.022). The improvement occurred in participants with strabismic amblyopia, but not in those with anisometropic amblyopia. Follow up data after about 1 year showed that VA had regressed to pre-treatment levels. The results are discussed within the context of another development in active amblyopia therapy, perceptual learning. The literature on this therapy reveals improvements in VA of about 2.5 lines in older children and adults with anisometropic amblyopia. It is concluded that perceptual learning is likely a better treatment option than IPS for anisometropic amblyopes, and probably also for strabismic amblyopes although a randomised controlled trial is required. It is noted that the existence of effective treatments for adults does not detract from the need to treat amblyopia in younger children.

Virtual reality in paediatric rehabilitation: a review

OBJECTIVE

To provide a narrative review of studies regarding the outcomes of Virtual Reality (VR)-based treatment and rehabilitation programmes within the paediatric population.

METHODS

Studies related to the use of VR across a number of paediatric areas (e.g. cerebral palsy, autism, foetal alcohol syndrome and attention deficits) were identified and summarized.

RESULTS

Outcomes from the studies reviewed provide preliminary support for the use of VR.

CONCLUSION

VR may be an effective treatment method for specific disorders, although the generalizability of this literature is hindered by several methodological limitations, such as small samples and the absence of appropriate control participants.

Neural mechanisms of recovery following early visual deprivation

Natural patterned early visual input is essential for the normal development of the central visual pathways and the visual capacities they sustain. Without visual input, the functional development of the visual system stalls not far from the state at birth, and if input is distorted or biased the visual system develops in an abnormal fashion resulting in specific visual deficits. Monocular deprivation, an extreme form of biased exposure, results in large anatomical and physiological changes in terms of territory innervated by the two eyes in primary visual cortex (V1) and to a loss of vision in the deprived eye reminiscent of that in human deprivation amblyopia. We review work that points to a special role for binocular visual input in the development of V1 and vision. Our unique approach has been to provide animals with mixed visual input each day, which consists of episodes of normal and biased (monocular) exposures. Short periods of concordant binocular input, if continuous, can offset much longer episodes of monocular deprivation to allow normal development of V1 and prevent amblyopia. Studies of animal models of patching therapy for amblyopia reveal that the benefits are both heightened and prolonged by daily episodes of binocular exposure.

A psychophysical study of human binocular interactions in normal and amblyopic visual systems

During infancy and childhood, spatial contrast sensitivity and alignment sensitivity undergo maturation, and during this period the visual system has considerable plasticity. The purpose of this study was to compare the nature of interocular interactions of these spatial functions in normally sighted children and adults, and to study the extent to which interocular interactions are impaired in anisometropic amblyopia. Spatial functions were measured under three viewing conditions: monocular (fellow eye occluded), dichoptic (uniform stimulus presented to the fellow eye but with a peripheral fusion lock), and binocular. Measurements were made in each eye during monocular and dichoptic viewing. In the contrast sensitivity task, Gabor stimuli were presented in one of two temporal intervals. For the alignment task, a three-element Gabor stimulus was used. The task of the subject was to indicate the direction of displacement of the middle patch with respect to the outer patches. The findings indicate that in children, binocular contrast sensitivity was better than monocular (binocular summation) but so too was dichoptic sensitivity (dichoptic summation). The magnitude of binocular/dichoptic summation was significantly greater in children than in normally sighted adults for contrast sensitivity, but not for alignment sensitivity. In anisometropic amblyopes, however, we find that for the group as a whole the amblyopic eye does not benefit when the fellow eye views a dichoptic stimulus, compared to dark occlusion of that eye. In addition, we found considerable inter-individual variation within the amblyopic group. Implications of these findings for techniques used in vision therapy are discussed.

Assessment of a computer-based treatment for older amblyopes: the Glasgow Pilot Study

PURPOSE

There have been few viable alternatives to patching the better eye as a treatment of amblyopia for more than two centuries. The success of patching depends on compliance, which is problematic for up to 59% of children and their families.

METHODS

This pilot study trialled the interactive binocular treatment (I-BiT) system as an alternative amblyopia treatment in 12 older amblyopes (6.1-11.4 years, median 8.2), who had not complied with or responded to occlusion. Virtual reality images were projected to each eye simultaneously via a headset during eight treatment sessions of 25-min duration. Outcome measures were changes in high- (HCVA) and low-contrast log MAR acuity (LCVA) at 1 week, 4 weeks and a final follow-up (3-18 months) after the final treatment.

RESULTS

Sustained improvements in HCVA were observed in seven children (58%) and in LCVA in eight children (67%), including two for whom amblyopia was eliminated. Five children had visual acuities equivalent to 6/12 or better at least 6 months after stopping treatment, compared with one child prior to treatment. Significant improvements in HCVA occurred up to the fourth treatment; in LCVA to the seventh treatment.

CONCLUSION

Sustained improvements in visual acuity were observed for 58% of this small group of children using the I-BiT system, despite prior failure with conventional treatment. This offers hope for a potential time-saving alternative to patching, in which compliance can easily be monitored, but the results need to be validated by means of a randomised controlled trial.