Peripheral retinal irradiation with low-energy red light can effectively and safely delay the progression of myopia.

Aims: To determine whether peripheral retinal irradiation with low-energy red light can effectively and safely delay the progression of myopia.

Methods: The guinea pigs (age, 2 weeks) were used. The central or peripheral retina was exposed to red light for 3 min each at 9:00 AM and 5:00 PM daily. At day 28, examinations were performed to assess the condition of axial length, the cornea and lens, and the central choroid thickness. The ratio of axial length at a given time to the baseline axial length was used to assess the axial length growth.

Results: Under the same energy density mode, illuminance (energy density) on the retina layer of peripheral irradiation is less than that of central irradiation. Under myopia induction, after 4 weeks of red light irradiation, the axial length ratios of the central and peripheral irradiation groups were 1.09±0.02 and 1.07±0.02, respectively, both significantly lower than the axial length ratio of 1.11±0.01 in the group with only myopia induction. Peripheral irradiation outperformed central irradiation in delaying axial elongation (p<0.05). Under the premise of myopia induction, peripheral irradiation but not central irradiation at 0.6 mW/cm² still delayed axial elongation. Both central and peripheral irradiation increased central choroidal thickness, with peripheral irradiation having a more pronounced effect.

Conclusion: Peripheral retinal irradiation with low-energy red light can effectively and safely slow axial growth while increasing central choroidal thickness. The follow-up period for the current study is 28 days, and the long-term safety of red light therapy for myopia necessitates further investigation.