Short-Term Changes in Children’s Eye Size with Cyan (Blue-Green) Light: A Short Trial

What is the intervention? The intervention consists of single-vision spectacles (SVS, control treatment) and cyan light exposure (Cyan+SVS, treatment intervention) delivered via custom-designed cyan light-emitting glasses worn over the participant’s habitual single-vision spectacle (SVS) correction. This light emitting glasses were developed and validated by Chakraborty et al. (2024) in collaboration with EssilorLuxottica (Paris, France), and are designed to emit controlled cyan wavelength light (peak wavelength 500 nm, a total average irradiance of 3.0W/m² and maximum irradiance 3.10 W/m²) for ocular stimulation. Who delivers it and their relevant expertise? The intervention is self-administered by participants at home, under the supervision of their caregivers/parents. Participants and caregivers will receive standardised instructions and training from the research team, who have expertise in vision science, clinical research, and paediatric eye studies. How is it delivered? Treatment Intervention: This intervention is delivered through wearable cyan light-emitting glasses, which participants will wear at home during scheduled sessions. The glasses are worn over the participant’s habitual single-vision spectacle (SVS) correction (if applicable) while engaging in normal indoor activities. Control treatment: The control condition is delivered through single-vision spectacles (SVS). Participants will be instructed to wear SVS during all waking hours (except during sleep or water-based activities), seven days per week, for a period of 4 weeks, and to avoid using any other forms of optical correction, including sunglasses. How often and for how long? Treatment intervention: Participants will be instructed to wear the glasses for two 20-minute sessions per day (total daily exposure: 40 minutes): One session in the morning (7:00–11:00 am) and another session in the afternoon (1:00–6:00 pm). The two sessions must be separated by at least 3 hours. This regimen will be followed daily (7 days per week) for 4 weeks. Control treatment: Participants will be instructed to wear SVS during all waking hours (except during sleep or water-based activities), seven days per week, for a period of 4 weeks, and to avoid using any other forms of optical correction, including sunglasses. Washout period: Participants will be randomly assigned to receive either treatment intervention or control intervention during the first four weeks of the study. After completing the first intervention period (weeks 1 through 4), participants will undergo a one-week washout period (week 5), after which they will undergo baseline measurements and cross over to the alternate intervention (weeks 6 through 9). Where is it delivered? The intervention is delivered at the participant’s home environment, allowing use during routine indoor activities. Adherence Adherence will be monitored using a daily logbook completed by participants and their caregivers, documenting each session of light exposure. These records will be reviewed by the research team to monitor compliance with the intervention protocol, identify any missed sessions or deviations and support ongoing safety monitoring throughout the study.