Binocular treatment of amblyopia using videogames (BRAVO): study protocol for a randomised controlled trial

Cindy X Guo, Raiju J Babu, Joanna M Black, William R Bobier, Carly S Y Lam, Shuan Dai, Tina Y Gao, Robert F Hess, Michelle Jenkins, Yannan Jiang, Lionel Kowal, Varsha Parag, Jayshree South, Sandra Elfride Staffieri, Natalie Walker, Angela Wadham, Benjamin Thompson, BRAVO study team, Taina Von Blaramberg, Stephen J Boswell, Arijit Chakraborty, Lily Chan, Simon Clavagnier, Patrick W C Ho, Colin Howe, Michelle H Jen, Lisa Kearns, Joanna Michie, Colleen Ng, John Faafetai Faatui, Peter Pang, Roberto Pieri, Rajkumar Nallour Raveendren, Daniel Spiegel, Stuart L Uren, Cindy X Guo, Raiju J Babu, Joanna M Black, William R Bobier, Carly S Y Lam, Shuan Dai, Tina Y Gao, Robert F Hess, Michelle Jenkins, Yannan Jiang, Lionel Kowal, Varsha Parag, Jayshree South, Sandra Elfride Staffieri, Natalie Walker, Angela Wadham, Benjamin Thompson, BRAVO study team, Taina Von Blaramberg, Stephen J Boswell, Arijit Chakraborty, Lily Chan, Simon Clavagnier, Patrick W C Ho, Colin Howe, Michelle H Jen, Lisa Kearns, Joanna Michie, Colleen Ng, John Faafetai Faatui, Peter Pang, Roberto Pieri, Rajkumar Nallour Raveendren, Daniel Spiegel, Stuart L Uren

Abstract

Background: Amblyopia is a common neurodevelopmental disorder of vision that is characterised by visual impairment in one eye and compromised binocular visual function. Existing evidence-based treatments for children include patching the nonamblyopic eye to encourage use of the amblyopic eye. Currently there are no widely accepted treatments available for adults with amblyopia. The aim of this trial is to assess the efficacy of a new binocular, videogame-based treatment for amblyopia in older children and adults. We hypothesise that binocular treatment will significantly improve amblyopic eye visual acuity relative to placebo treatment.

Methods/design: The BRAVO study is a double-blind, randomised, placebo-controlled multicentre trial to assess the effectiveness of a novel videogame-based binocular treatment for amblyopia. One hundred and eight participants aged 7 years or older with anisometropic and/or strabismic amblyopia (defined as ≥0.2 LogMAR interocular visual acuity difference, ≥0.3 LogMAR amblyopic eye visual acuity and no ocular disease) will be recruited via ophthalmologists, optometrists, clinical record searches and public advertisements at five sites in New Zealand, Canada, Hong Kong and Australia. Eligible participants will be randomised by computer in a 1:1 ratio, with stratification by age group: 7-12, 13-17 and 18 years and older. Participants will be randomised to receive 6 weeks of active or placebo home-based binocular treatment. Treatment will be in the form of a modified interactive falling-blocks game, implemented on a 5th generation iPod touch device viewed through red/green anaglyphic glasses. Participants and those assessing outcomes will be blinded to group assignment. The primary outcome is the change in best-corrected distance visual acuity in the amblyopic eye from baseline to 6 weeks post randomisation. Secondary outcomes include distance and near visual acuity, stereopsis, interocular suppression, angle of strabismus (where applicable) measured at baseline, 3, 6, 12 and 24 weeks post randomisation. Treatment compliance and acceptability will also be assessed along with quality of life for adult participants.

Discussion: The BRAVO study is the first randomised controlled trial of a home-based videogame treatment for older children and adults with amblyopia. The results will indicate whether a binocular approach to amblyopia treatment conducted at home is effective for patients aged 7 years or older.

Trial registration: This trial was registered in Australia and New Zealand Clinical Trials Registry ( ACTRN12613001004752 ) on 10 September 2013.

Keywords: Amblyopia; Binocular vision; Perceptual learning; Plasticity; Suppression; Videogame.

Figures

Fig. 1
Fig. 1
Study schematic. Legend: study flow from recruitment and screening to the final 24-week follow-up

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