After-School Solar Exposure and Myopia: Comparison of Subjective Assessments and Dosimetric Measurements

This study aimed to compare subjective (questionnaire-based) and objective (dosimeter-based) measurements of children's outdoor activity, to improve assessment methods for future research on the potential impact of outdoor activity on myopia development.

The study was conducted among children aged 5 to 11 years in Lisbon, Portugal. Subjective data on after-school outdoor activities during weekdays were collected using the "Myopia Risk Assessment Worksheet," completed by parents to report their child's typical after-school outdoor time. Objective measurements for the same period were obtained using UV dosimeters worn by participants, recording their exposure to solar radiation between 4:00 PM and 9:00 PM on weekdays. The analysis compared these two data sources to evaluate their agreement and to assess the accuracy of self-reported after-school outdoor activity.

The results indicated a moderate correlation (rs = 0.417; p < 0.001) between questionnaire responses and dosimetric data, with self-reported data typically underestimating outdoor exposure compared to dosimetric measurements. The median difference was -0.25 h/day (95% CI: -0.52 to 0.15 h/day), indicating no significant systematic bias in the overall sample. However, variability in differences increased with longer outdoor times, as shown by a positive slope of 0.540 (p < 0.001) in the regression of absolute residuals on average outdoor time.

This study demonstrates that lifestyle questionnaires and dosimetric measurements yield moderately correlated estimates of weekly UV exposure, with minimal differences between them. Combining subjective and objective methods enhances the accuracy of assessing children's outdoor exposure, an essential factor in developing effective myopia prevention strategies.