Estimating the magnitude of close-up work in school-age children: a comparison of questionnaire and diary instruments

Abstract

Background: Numerous scientists have noted a relationship between close-up work and myopia.

Methods: A questionnaire and four 24-hour diaries were developed to estimate close-up work activity in a cohort study of close-up work and myopia progression in Singapore children. The number of hours per day that children engaged in each type of close-up work activity over a weekday and weekend during the school term, during the examination period, and in the vacation were estimated.

Results: The children spent an average of 6.6 hours per day on total weighted average close-up work, of which 4.3 hours were spent on reading and writing. The intra-class correlation coefficient for the reproducibility of the questionnaire was 0.87 (95% CI 0.85-0.91). The intra-class correlation coefficient for total weighted close-up work was 0.50 (95% CI 0.34-0.66) when the questionnaire was compared with the four 24-hour diaries. The amount of close-up work activity increased with age.

Conclusions: A questionnaire for close-up work was developed and proven to be reproducible and comparable to four 24-hour diaries.