An Objective Comparison of Light Intensity and Near-Visual Tasks Between Rural and Urban School Children in China by a Wearable Device Clouclip

Purpose: To compare light intensity and near-visual tasks objectively between rural and urban children.

Methods: Clouclip, a wearable device, was applied to assess metrics of these two factors in 78 fifth-grade students from an urban and from a rural school.

Results: The light intensity experienced by urban students was found significantly lower both in the school period (614.05 ± 178.77 vs. 918.41 ± 257.81 lux, P < 0.001) and on the weekend (444.53 ± 216.65 vs. 882.21 ± 536.67 lux, P < 0.001). The duration of exposure to bright light (>1000 lux) was also substantially shorter for urban students. Although no significant difference was found in near work-related behaviors during the school period and the weekend, for the after-school period the urban students had a shorter average viewing distance (30.94 ± 4.14 vs. 34.81 ± 3.93 cm, P < 0.001), a longer accumulated duration of near work (2.25 ± 0.53 vs. 1.95 ± 0.46 hours, P = 0.010), a greater time ratio of near work (56% ± 14% vs. 49% ± 14%, P = 0.045), and a greater time ratio of excessively close near work (49% ± 13% vs. 40% ± 12%, P = 0.001).

Conclusions: Our data indicate there were substantial differences in light exposure and near-work metrics between the two regions. The correlation between these differences and the discrepancy in regional myopia prevalence needs further investigation.

Translational relevance: The objective quantification of these metrics might help explain the varied myopia prevalence among regions.