A recent review found no irreversible visual function loss or ocular structural damage in individuals undergoing repeated low-level red-light (RLRL) therapy for myopia.  

Analysing 20 studies (including 2,380 participants aged 3–18 years and 1,436 individuals undergoing RLRL therapy), the review found two case reports describing one patient with reversible decline in visual acuity and OCT abnormalities, which completely resolved four months after treatment cessation. No cases of permanent vision loss were reported.  

The most commonly reported side-effect was temporary afterimage, resolving within six minutes after treatment.  

To identify any side effects, fundus photography and OCT prior to and during therapy, alongside home monitoring of visual acuity and duration of afterimages, are required, wrote authors. They also recommended studies of longer duration are required to evaluate long-term safety of RLRL therapy.