Sustained Effect of Red-light Therapy for Myopia Control: A 2-Year Post-Trial Follow-up Study

Change of axial length (mm) with the measurement of device named by IntraOcular Lens Master(IOLmaster 500)

To evaluate the long-term efficacy and safety of red-light therapy for myopia control over 2
 years, and the potential rebound effect after treatment cessation.
 
 The Chinese myopic children who originally completed the one-year randomised controlled trial
 in the previous study were enrolled. Children continued or started to daily usage of
 red-light therapy were defined as the RL group, while those who stopped using red-light
 therapy and switched to single-vision spectacles (SVS) as well as those who continued to keep
 single-vision spectacles in the second year were both regarded as the SVS group. Red-light
 therapy was provided by an at-home desktop light device emitting red-light of 650 nm and was
 administered for 3 min at a time, twice a day. Changes in axial length (AL) and cycloplegic
 spherical equivalence refraction (SER) are to be measured and compared as well as the adverse
 effects including the rebound effect.
 
 Red-light therapy has emerged as a novel myopia control treatment modality recently. A
 12-month randomised controlled trial (RCT) conducted by our research team was thought to be
 earlier to evaluate the treatment of myopic children using red-light therapy. The trial
 demonstrated that PBM therapy was effective on myopia control, reducing axial elongation and
 spherical equivalence refraction (SER) progression 103% and 127% compared with single vision
 spectacle (SVS) over a 12-month period, respectively. The promising efficacy of red-light
 therapy has been further confirmed in other studies. In addition, satisfactory user
 acceptability and no unrecovered functional and structural damages were observed.
 
 Myopia generally progresses throughout childhood and hence a study duration of 1 year is not
 sufficient to widely adopt the red-light therapy as a treatment strategy for myopia control.
 The sustainability of treatment efficacy, rebound phenomenon upon cessation of treatment, and
 potential risks and adverse effects in myopic children with longer-term PBM therapy, remain
 to be fully elucidated.
 
 Thus, the aims of this post-trial follow-up study were to invite the participants to come
 back for a 24-month visit and to investigate the long-term efficacy and safety of continued
 red-light therapy as well as the potential rebound effect following red-light treatment
 cessation.