The association between smartwatch usage and myopia progression in primary school students: a 1-year prospective observation.

OBJECTIVE

To explore the association between smartwatch usage and annual changes in refraction and axial length in primary school students.

METHODS

A 1-year prospective, school-based, observational study. 661 students (Grade 5 at baseline, ages 11-13) were invited. The cycloplegic spherical equivalent refraction (SER), axial length (AL) and questionnaires were measured at baseline and 1-year visit.

RESULTS

Five hundred twenty-six participants (mean age, 11.31 ± 0.47 years; 52.3% male) completed the 1-year study, and were divided into three groups based on smartwatch time (<0.5, 0.5-1, >1 h/day). Participants with more daily smartwatch usage (>1 h/day) showed more significantly myopic shift in refraction (-0.95 D) and axial elongation (0.47 mm) compared to those with moderate (0.5-1 h/day: -0.29 D and 0.25 mm) or low (<0.5 h/day: -0.33 D and 0.28 mm) usage (both p < 0.001). The weekday time of the smartwatch was strongly associated with changes in SER (r = -0.173, p < 0.001) and AL (r = 0.163, p < 0.001). The generalised linear mixed model (GLMM) revealed that total screen time (β = -0.07 for SER change, β = 0.03 for AL change, both p < 0.001) and weekday smartwatch usage (β = -0.58 for SER change, β = 0.16 for AL change, both p < 0.001) were significantly associated with myopic shifts in refraction and axial elongation.

CONCLUSIONS

Observational data indicate an association between total screen time (including smartwatch) and myopic shifts in refraction or axial elongation. These findings suggest that reasonable management of screen time may be warranted.