Published Literature On Binocular Approach in Amblyopia Treatment

Title: Evaluation of the Efficacy of a New Dichoptic Digital Platform to Treat the Anisometropic and Isometropic Amblyopia

Authors: Md Oliullah Abdal 1, Faiza Bhombal 1, Gul J. Nankani 1,Sonia G. Nankani 1,Shruti Lad 1, Aditi Dholam 1,Richa Kumari 1,Jinal Mahajan 1 and David P. Piñero 2,3,*


The aim of the current study was to evaluate the results of a novel dichoptic training program using an online platform in a group of subjects with refractive amblyopia, performing a comparative analysis of unilateral and bilateral amblyopic cases. For this purpose, a retrospective study analysis of data of 161 children (4-13 years) who underwent dichoptic treatment with the Bynocs ® platform (Kanohi Eye Pvt. Ltd., India) was performed. In all cases, the therapy protocol consisted of sessions of training of 30 min daily 5 times a week for 6 weeks. Best corrected visual acuity (BCVA) in the non-dominant eye improved significantly with the treatment, with a mean change of 0.39 logMAR in the whole sample (p < 0.001). Regarding binocularity, the binocular function (BF) score also experienced a significant improvement (p < 0.001), with a mean change of 1.55 with therapy in the whole sample. The BCVA of the dominant eye only improved significantly (p < 0.001) in the isometropic amblyopic subgroup. In conclusion, the use of the dichoptic therapy with the digital platform evaluated allows an effective restoration of visual acuity and binocular function in children with anisometropic and isometropic amblyopia.

Title: Stimuli Characteristics and Psychophysical Requirements for Visual Training in Amblyopia: A Narrative Review

Authors: Carlos J. Hernandez-Rodriguez, David P. Piller°,* , Ainhoa Molina-Martin , Leon Morales-Quezada, Dolores de Fez, Luis Leal-Vega, Juan F. Arenillas and Maria Begolia Coco-Martin


Active vision therapy using perceptual learning and/or dichoptic or binocular environments has shown its potential effectiveness in amblyopia, but some doubts remain about the type of stimuli and the mode and sequence of presentation that should be used. A search was performed in PubMed, obtaining 143 articles with information related to the stimuli used in amblyopia rehabilitation, as well as to the neural mechanisms implied in such therapeutic process. Visual deficits in amblyopia and their neural mechanisms associated are revised, including visual acuity loss, contrast sensitivity reduction and stereopsis impairment. Likewise, the most appropriate stimuli according to the literature that should be used for an efficient rehabilitation of the amblyopic eye are described in detail, including optotypes, Gabor’s patches, random-dot stimuli and Vernier’s stimuli. Finally, the properties of these stimuli that can be modified during the visual training are discussed, as well as the psychophysical method of their presentation and the type of environment used (perceptual learning, dichoptic stimulation or virtual reality). Vision therapy using all these revised concepts can be an effective option for treating amblyopia or accelerating the treatment period when combining with patching. It is essential to adapt the stimuli to the patient’s individual features in both monocular and binocular training.

Title: Effect of dichoptic video game treatment on mild amblyopia – a pilot study

Authors: Peter C. K. Pang, Carly S. Y. Lam, Robert F. Hess, and Benjamin Thompson


Purpose: The effect of contrast-balanced dichoptic video game training on distance visual acuity (DVA) and stereo acuity has been investigated in severe-tomoderate amblyopia, but its effect on mild amblyopia and fixation stability has not been assessed. This pilot study aimed to evaluate the effect of home-based dichoptic video game on amblyopic eye DVA, stereo acuity and fixation stability in adults with mild amblyopia.

Methods: A randomized single-masked design was adopted. The active 6-week home-based treatment was an anaglyphic, contrast-balanced dichoptic video game, and the placebo was an identical non-dichoptic game. Participants (n = 23) had mild amblyopia (amblyopic DVA ≤ 0.28 log Minimum Angle of Resolution (logMAR)). The primary outcome was change in amblyopic DVA at 6 weeks postrandomization. Near visual acuity, stereo acuity and fixation stability (bivariate contour eclipse area) were also measured. Follow-up occurred at 12 and 24 weeks postrandomization.

Results: Mean amblyopic eye DVA was 0.21 0.06 and 0.18 0.06 logMAR for the active (n = 12) and placebo (n = 11) group, respectively. Amblyopic DVA improved significantly more in the active group (0.09 0.05) than in the placebo group (0.03 0.04 logMAR; p < 0.05). The difference between groups remained at 12 weeks postrandomization (p = 0.04) but not at 24 weeks (p = 0.43). Titmus stereo acuities improved significantly more in the active group (0.40 log arcsec) than in the placebo group (0.09 log arcsec) after 6 weeks of gameplay. The betweengroup difference was still present at 24 weeks postrandomization (p = 0.05). There were no differences between groups on any other secondary outcomes.

Title: Active Vision Therapy for Anisometropic Amblyopia in Children: A Systematic Review

Authors: Carlos J. Hernandez-Rodriguezl and David P. Piriero


The aim of the study was evaluation of the scientific evidence about the efficacy of vision therapy in children and teenagers with anisometropic amblyopia by performing a systematic literature review. Methods. A search was performed using 3 searching strategies in 4 different databases (PubMed, Web of Science, Scopus, and PruQuest). The quality of the included articles was evaluated using two tools for the risk of bias assessment, ROBINS-I for nonrandomized studies of intervention (NRSI), and ROB 2.0 for randomized clinical trials. Results. The search showed 1274 references, but only 8 of them passed the inclusion criteria after the complete text review. The articles that were finally included comprised 2 randomized control trials and 6 nonrandomized studies of intervention. These articles provided evidence supporting the efficacy of vision therapy for the treatment of aniso-metropic amblyopia in children and teenagers. Assessment of the risk of bias showed an appropriate risk of bias for the randomized control trials, but a high risk of bias for nonrandomized studies of intervention (NRSI). A main source of risk of bias for NRSI was the domain related to the measurements of the outcomes, due to a lack of double-blind studies. Conclusion. Vision therapy is a promising option for the treatment of anisometropic amblyopia in children and teenagers. However, the level of scientific evidence provided by the studies revised is still limited, and further randomized clinical trials are necessary to confirm the results provided to date and to optimize the vision therapy techniques by knowing the specific neural mechanisms involved.

Title: Binocular amblyopia treatment with contrast-rebalanced movies

Author: By Bynocs0


Binocular amblyopia treatments promote visual acuity recovery and binocularity by reba- lancing the signal strength of dichoptic images. Most require active participation by the amblyopic child to play a game or perform a repetitive visual task. The purpose of this study was to investigate a passive form of binocular treatment with contrast-rebalanced dichoptic movies.


A total of 27 amblyopic children, 4-10 years of age, wore polarized glasses to watch 6 contrast-rebalanced dichoptic movies on a passive 3D display during a 2-week period. Amblyopic eye contrast was 100%; fellow eye contrast was initially set to a lower level (20%-60%), which allowed the child to overcome suppression and use binocular vision. Fellow eye contrast was incremented by 10% for each subsequent movie. Best-corrected visual acuity, random dot stereoacuity, and interocular suppression were measured at base- line and at 2 weeks.


Amblyopic eye best-corrected visual acuity improved from 0.57 T 0.22 at baseline to 0.42 T 0.23 IogMAR (t26 5 8.09; P \ 0.0001; 95% CI for improvement, 0.11-0.19 log- MAR). Children aged 3-6 years had more improvement (0.21 T 0.11 IogMAR) than chil- dren aged 7-10 years (0.11 T 0.06 IogMAR; t25 5 3.05; P 5 0.005). Children with severe amblyopia ($0.7 IogMAR) at baseline experienced greater improvement (0.24 T 0.12 log- MAR) than children with moderate amblyopia at baseline (0.12 0.06 IogMAR; t25 5 3.49; P 5 0.002).

Title: Dichoptic therapy improves visual acuity in residual amblyopia - A Prospective trial

Authors: Md Oliullah Abdal M. Opt., Faiza Bhombal B Opt., Shruti Lad B Opt., Sonia Nankani MS, Gul Nankani MS.


  • Amblyopia is a developmental disorder with a binocular consequence; it has a prevalence of 2-5%. 
  • Patching is not very effective and is usually left with residual amblyopia in older children and adults. 
  • Deficits in Binocularity (fusion and stereopsis), hand-eye coordination saccades, and pursuits. 

Dhicoptic Treatments – Principles: A (contrast adjusted) stimulus is presented exclusively to each eye & the brain is forced to integrate the images into a single perception.  

Title: A Randomized Trial of Binocular Dig Rush Game Treatment for Amblyopia in Children Aged 7 to 12 Years

Authors: Jonathan M. Holmes, BM, BCh,’ Ruth E. Manny, OD, PhD, Elizabeth L. Lazar, MS, MPH,’ Eileen E. Birch, PhD , Krista R. Kelly, PhD,’ Allison I. Summers, OD, MCR , Stacy R. Martinson, OD , Aparna Raghuram, OD, PhD, Jeffrey D. Colburn, MD, Christine Law, MD, Justin D. Marsh, MD,’° Derek P. Bitner, MD,’ Raymond T. Kraker, MSPH , David K. Wallace, MD, MPH”


Purpose: To compare visual acuity (VA) improvement in children aged 7 to 12 years with amblyopia treated with a binocular iPad game plus continued spectacle correction vs. continued spectacle correction alone.

Design: Multicenter randomized clinical trial.

Participants: One hundred thirty-eight participants aged 7 to 12 years with amblyopia (33-72 letters, i.e., approximately 20/200 to 20/40) resulting from strabismus, anisometropia, or both. Participants were required to have at least 16 weeks of optical treatment in spectacles if needed or demonstrate no improvement in amblyopic-eye visual acuity (VA) for at least 8 weeks prior to enrollment.

Methods: Eligible participants (mean age 9.6 years, mean baseline VA of 59.6 letters, history of prior amblyopia treatment other than spectacles in 96%) were randomly assigned to treatment for 8 weeks with the dichoptic binocular Dig Rush iPad game (prescribed for 1 hour per day 5 days per week) plus spectacle wear if needed (n 69) or continued spectacle correction alone if needed (n = 69).

Main Outcome Measures: Change in amblyopic-eye VA from baseline to 4 weeks, assessed by a masked examiner.

Results: At 4 weeks, mean amblyopic-eye VA letter score improved from baseline by 1.3 (2-sided 95% confidence interval [CI]: 0.1-2.6; 0.026 logMAR) with binocular treatment and by 1.7 (2-sided 95% CI: 0.4-3.0; 0.034 logMAR) with continued spectacle correction alone. After adjusment for baseline VA, the letter score dif-ference between groups (binocular minus control) was -0.3 (95% CI: -2.2 to 1.5, P 0.71, difference of -0.006 logMAR). No difference in letter scores was observed between groups when the analysis was repeated after 8 weeks of treatment (adjusted mean: -0.1, 98.3% CI: -2.4 to 2.1). For the binocular group, adherence data from the iPad indicated that slightly more than half of the participants (58% and 56%) completed 75% of prescribed treatment by the 4- and 8-week visits, respectively.

Title: Outcome of New Computer-Based Binocular Vision Therapy in Residual Amblyopia – A Pilot Study

Authors: Kothari Mihir, Vivek Rathod, Abdal Oli Ullah, and Lad Shruti


Aim: To assess the efficacy of dichoptic therapy in the management of residual amblyopia.

Methods: In this prospective cohort study, children aged ≥ 6 years or adults with isoametropic (inter eye acuity difference of ≥ 2

lines), anisometropic or strabismic residual amblyopia were treated with 6 hours/week of office therapy (group 1) and 2 hours/day

patching or 5 hours/week of home therapy (group 2) sans patching were evaluated after 6 weeks of therapy.

Results: In the office therapy group; 16 eyes of 11 children were included. 5 had bilateral (one eye more affected) and 6 had unilateral (anisometropic/strabismic/mixed) amblyopia. Mean age was 12.5 years. Mean improvement in bilateral amblyopia (n = 10) was 0.26, p < 0.01 (paired t test) and in unilateral amblyopia (n = 5) it was 0.28, p = 0.05. Maximum improvement in bilateral amblyopia was 0.48 (5 lines on logMAR chart) and in unilateral was 0.6 (6 lines). 4 patients with age > 18 years experienced mean 2.5 lines improvement. In home therapy group, seven eyes of seven patients aged 6 – 15 years were included. Five had strabismic amblyopia and 2 had anisometropic amblyopia. The best corrected vision improved in all with a mean 1.8 lines improvement (range 1 – 3 lines).

Conclusion: The new dichoptic therapies are promising treatment for patients with residual amblyopia. The office therapy along with part time patching was more effective than home therapy. Further studies are needed to identify the long-term efficacy of these therapies.

Title: Amblyopia and the binocular approach to its therapy

Authors: Robert F. Hess, Benjamin Thompson


There is growing evidence that abnormal binocular interactions play a key role in amblyopia. In particular, stronger suppression of the amblyopic eye has been associated with poorer amblyopic eye visual acuity and a new therapy has been described that directly targets binocular function and has been found to improve both monocular and binocular vision in adults and children with amblyopia. Furthermore, non-invasive brain stimulation techniques that alter excitation and inhibition within the visual cortex have been shown to improve vision in the amblyopic eye. The aim of this review is to summarize this previous work and interpret the therapeutic effects of binocular therapy and non-invasive brain stimulation in the context of three potential neural mechanisms; active inhibition of signals from the amblyopic eye, attenuation of information from the amblyopic eye, and metaplasticity of synaptic long term potentiation and long term depression.

Title : A Game Platform for Treatment of Amblyopia

Authors: Benjamin Thompson, Jeffrey R. Blum, Goro Maehara, Robert F. Hess, and Jeremy R. Cooperstock


We have developed a prototype device for take-home use that can be used in the treatment of amblyopia. The therapeutic scenario we envision involves patients first visiting a clinic, where their vision parameters are assessed and suitable parameters are determined for therapy. Patients then proceed with the actual therapeutic treatment on their own, using our device, which consists of an Apple iPod Touch running a specially modified game application. Our rationale for choosing to develop the prototype around a game stems from multiple requirements that such an application satisfies. First, system operation must be sufficiently straightforward that ease-of-use is not an obstacle. Second, the application itself should be compelling and motivate use more so than a traditional therapeutic task if it is to be used regularly outside of the clinic. This is particularly relevant for children, as compliance is a major issue for current treatments of childhood amblyopia. However, despite the traditional opinion that treatment of amblyopia is only effective in children, our initial results add to the growing body of evidence that improvements in visual function can be achieved in adults with amblyopia.