Changes in choroidal thickness in pre-myopic children after repeated low-level red-light therapy and their role in predicting myopia prevention and controlling myopic shift.

Purpose: To investigate longitudinal changes in choroidal thickness (ChT) after 1-year treatment of repeated low-level red-light (RLRL) and their predictive value in efficacy on myopia prevention and myopic shift among pre-myopic children.

Methods: 278 pre-myopic (-0.50 D < spherical equivalent refraction, SER ≤ 0.50 D) participants were assigned to the RLRL group and control group randomly and evenly. The OCT, visual acuity, AL, SER and other parameters were measured before enrollment and every 3 months after intervention. The data from both eyes of the included participants were analyzed.

Results: A total of 463 eyes were analyzed. Due to the COVID-19 pandemic, 176 participants in the RLRL group had treatment interrupted. The continued RLRL group, interrupted RLRL group and control group were well balanced in baseline characteristics. In the continued and interrupted RLRL group, the average ChT increased significantly at 3-month visit (all P < 0.001) and the subfoveal ChT thickened evidently. The area under the curve (AUC) for the models including gender and 3-month change in ChT to predict satisfactory myopia prevention at 12 months was 0.983. The efficacy of the models that also used the combined indicators of baseline age, gender and the 3-month change in ChT to predict AL progression control over 12 months reached 0.944.

Conclusions: Continued RLRL intervention induced notable thickening of ChT in premyopic population, especially at the subfoveal sector. For participants received RLRL treatment, the 3-month change in ChT combined with other baseline factors have acceptable predictive discrimination of myopia prevention efficacy.