Effectiveness of bright light therapy and combination with myopic defocus for controlling myopic eye growth in schoolchildren: study protocol for a randomised controlled trial (phase 1).

Introduction: Myopia and its complications can lead to irreversible visual impairment and even blindness, making this a worldwide public health concern for the 21st century. While treatments to slow myopia progression exist, their average efficacy is moderate. Bright light exposure, either in controlled animal models or naturally under sunlight for children, has demonstrated a protective effect against myopia development. This study hypothesises that bright light therapy (BLT), delivered via a home-based device mimicking sunlight, could slow myopia progression in schoolchildren.

Methods and analysis: We propose a 2-year, double-masked, randomised controlled trial to investigate the effectiveness of BLT and its combination with myopia control treatment in schoolchildren. Chinese schoolchildren aged 7-12 years will be recruited and randomly assigned to one of three arms in phase 1. Subjects will be instructed to perform a minimum of 45 mins of near tasks daily under either BLT (10 000 lux white Light Emitting Diode (LED) light) or placebo light therapy (500 lux white LED light). The control subjects will receive single-vision spectacles and placebo light therapy; the single treatment subjects will receive single-vision spectacles and BLT; and the combination treatment subjects will receive defocus-incorporated multiple segments spectacles and BLT. The primary and secondary outcome measures are changes in cycloplegic objective refraction and axial length over a 2-year period.Treatment dosage is indirectly measured using a monitoring sensor attached beneath the BLT lamp rather than a wearable light metre. Variations in dosage monitoring may influence the observed treatment efficacy.

Ethics and dissemination: The study has been approved by the Institutional Review Boards of The Hong Kong Polytechnic University (HSEARS 20180829002-05) and The University of Hong Kong/Hospital Authority Hong Kong West Cluster (UW 20-362). The study results will be disseminated in scientific conferences and peer-reviewed indexed journals.

Trial registration number: ClinicalTrials.gov identifier: NCT04923841.