When evaluating treatments for myopia, especially in children, safety is of the utmost importance. Understanding the safety profile of low-level red-light (RLRL) therapy is essential for both patients and eye care professionals.

The safety of laser products for the eye depends on various factors including their power, distance from the eye, size of the beam, and duration of exposure. One of the most used device (Eyerising) reported it incorporated semiconductor laser diodes that emit low-level red light at a wavelength of 650 ± 10 nm. This light, with an illuminance level of about 1600 lux, is directed through a 4-mm pupil to the fundus of the eye with power of 0.29mW, and it complies with IEC 60825-1:2014 standard for laser products safety.

In the series of RCTs on RLRL, safety parameters such as Best Corrected Visual Acuity (BCVA), Uncorrected Visual Acuity (UCVA), Optical Coherence Tomography (OCT), and adverse events were closely monitored. The good news is that no severe adverse events, functional visual loss, or structural damage on OCT scans were observed among the participants.

More sensitive functional assessments such as multifocal electroretinogram (mfERG) and microperimetry are challenging to administer in young children, and are not included in the most published RCTs. As a supplement, a 12-month RCT studying RLRL therapy for myopia reported that no changes occurred in the mfERG and contrast sensitivity after red light therapy, indicating its safety.

Despite these promising results, the strict inclusion criteria and research protocols used in RCTs may limit the broader application of RLRL therapy in everyday clinical practice. This underscores the need for further investigation into its safety in real-world settings(19).

The most commonly reported side effects are mild and include transient visual phenomena such as prolonged after-images. Child may still perceive the red light or some form of light in their vision after treatment. It typically resolve shortly after discontinuing use of the therapy. There have also been cases of skin irritation of the eyelids, as well as cases in which the red light was felt to be too harsh for the eyes to be irradiated(20).

Reference:

19. Zhu M, Liu Y, Fang D, Li M, Fu T, Yao K, et al. Safety of repeated low-level red-light therapy for children with myopia. Photodiagnosis Photodyn Ther. 2024 Jun;47:104198.

20. Expert consensus on repeated low-level red-light as an alternative treatment for childhood myopia ( 2022).