Radiometric and safety assessment of a 'low-level red-light' myopia control device

Area of Science:

• Ophthalmology
• Biomedical Optics
• Medical Devices

Background:

• Low-level red-light therapy shows promise for slowing axial elongation in children.
• Concerns exist regarding the safety of some red-light devices used for myopia control.
• Understanding the optical characteristics and potential hazards is crucial for device safety.

Purpose of the Study:

• To investigate the beam characteristics of a specific red-light myopia control device (SECONEE sky-n1201a).
• To assess the potential retinal hazard posed by the device's light emission.
• To compare retinal exposure levels against established safety standards.

Main Methods:

• Quantified beam divergence and total flux through artificial pupils (1-9 mm).
• Measured exit vergences based on interpupillary distance settings.
• Compared retinal exposure levels to American National Standards Institute (ANSI) Z80.36-2021 limits.

Main Results:

• The device emitted collimated red light beams (655 nm) with variable exit vergences.
• Radiant power increased with artificial pupil diameter.
• Retinal exposures exceeded ANSI thermal and photochemical limits for pupil diameters >1 mm and >5 mm, respectively.
• Potential photochemical hazard was reached in under 100 seconds for pupils >5 mm.

Conclusions:

• The device's optical design results in retinal exposures dependent on pupil size, accommodation, and eye movements.
• Retinal radiant exposures can exceed ANSI safety limits, challenging the 'low-level' designation.
• Further safety evaluations are warranted for red-light myopia control devices.