Clinically Significant Axial Shortening in Myopic Children After Repeated Low-Level Red Light Therapy: A Retrospective Multicenter Analysis.

Abstract

Myopia is recognized as a progressive eye disease. The aim of this study was to evaluate the frequency and associated factors of clinically significant axial length (AL) shortening among myopic children following repeated low-level red light (RLRL) therapy. The clinical data that were collected for the myopic children aged 3-17years who received an RLRL therapy delivered by home-use desktop light device that emitted light at 650nm for at least 1year, were reviewed. The clinical data included AL, spherical equivalent refraction (SER), and visual acuity measured at baseline and follow-up. The primary outcomes were frequency of AL shortening of > 0.05mm, > 0.10mm, and > 0.20mm per year, and associated factors of AL shortening per year. A total of 434 myopic children with at least 12months of follow-up data were included. The mean age of participants was 9.7 (2.6) years with SER of -3.74 (2.60) diopters. There were 115 (26.50%), 76 (17.51%), and 20 (4.61%) children with AL shortening based on cutoffs of 0.05mm/year, 0.10mm/year, and 0.20mm/year, respectively. In the multivariable model, AL shortening was significantly associated with older baseline age, female gender, and longer baseline AL or greater spherical equivalent refraction (all P < 0.05). Among AL shortened eyes, the mean AL difference (standard deviation, SD) was -0.142 (0.094) mm/year. Greater AL shortening was observed among children who were younger and had longer baseline AL (all P < 0.05). More than a quarter of children had AL shortening > 0.05mm following RLRL therapy, and the overall mean AL change was -0.142mm/year. Further studies should explore the mechanisms underlying AL shortening.