Corneal Physician Bulletin: Twenty-Minute Continuous Use of Smart Phones Linked With Greater Myopia

Twenty-minute ongoing use of smartphones was linked with greater myopia in teenagers, particularly in those who had low exposure to the outdoors, reports a cross-sectional population-based study in Ophthalmology.1
            Specifically, close to 20% of the teens, — 525 with an average of age 13 and 54% girls — had myopia. Continuous smartphone use on average was 6.42 (4.36) episodes of 20 minutes without breaks/day, and was significantly associated with spherical equivalency (SER), axial length (AL) and corneal radius (CR) (β=-0.07, 95%CI=-0.13, -0.01; β=0.004, 95%CI=0.001-0.008, respectively). When assessing outdoor exposure, continuous use remained significant only with low exposure (β=-0.10, 95%CI=-0.20, -0.01 and β=0.007, 95%CI=0.001-0.013 for SER and AL/CR, respectively). Smartphone use during weekends was not significantly linked with SER and AL/CR, and either was face-to-screen distance.
            The study, which sought to investigate the link between smartphone use and axial length and refractive error in teenagers, employed a smartphone application (Myopia app) designed to objectively measure smartphone use and face-to-screen distance, and to inquire about outdoor exposure at regular intervals. The teens, who attended six secondary schools in The Netherlands, underwent cycloplegic refractive error and ocular biometry measurements.  
            The study’s researchers say the findings suggest that frequent smartphone breaks should become a recommendation for teens, and that future large longitudinal studies will enable additional detail on safe screen use in children.

1. Enthoven CA. Polling JR, Verzijden T, et al. Smartphone use associated with refractive error in teenagers; the Myopia app Study. Ophthalmology. 2021 Jul 7;S0161-6420(21)00518-2.