Transient ocular effects of common near tasks in children

To quantify transient changes in axial length and choroidal thickness in children after near work and determine whether responses differ between printed and digital tasks.

In this prospective, randomized, crossover study, 26 children, ages 13.2 ± 2.2 years (16 nonmyopes, 10 myopes) completed two 30-min near tasks at 20 cm, reading printed text and digital viewing, separated by a 30-min distance-viewing interval. Axial length (LenStar) and choroidal thickness (optical coherence tomography, Spectralis) were measured at baseline and after 10, 20, and 30 min of each task. Accommodative stimulus response functions (2-5 D) were measured objectively. Data were analyzed using repeated-measures ANOVA.

Following near work, axial length demonstrated a significant increase (p < 0.001), evident after 10 min and sustained through 30 min, independent of task type and with no differences between refractive groups. For choroidal thickness, there was no main effect of time or refractive group, but a significant main effect of task (p = 0.002), with 3 ± 1 μm more thinning following the printed task than the digital task. Furthermore, post hoc analysis showed a significant decrease of -3 ± 1 μm after 10 min of near work (p = 0.03). Myopic children showed a greater lag in the stimulus response function (p < 0.03), with a significant difference at 2 and 5 D.

Near work induced acute axial elongation and choroidal thinning in children, detectable within 10 min. Responses were similar between printed and digital tasks. This study adds to growing evidence that visual behavior may influence early ocular growth signals relevant to myopia development.