The longitudinal associations of reading, writing and screen time with myopia at age 9 years among children from the GUSTO birth cohort.

Purpose: To investigate the associations between paper-based reading and writing time, screen-based time at ages 2, 3, 6 and 9 years and myopia at age 9 in the GUSTO birth cohort.

Methods: The GUSTO study recruited pregnant women from two Singapore public maternity hospitals between 2009 and 2010. Parent-reported reading and writing time, screen time and outdoor time were collected at ages 2, 3, 6 and 9 years. Cycloplegic autorefraction and axial length were measured at age 9. Myopia was defined as a spherical equivalent ≤-0.5 D. Associations between near work exposures and myopia were examined using multivariable regression with generalised estimating equations.

Results: Among 471 children (942 eyes), 37.3% were myopic at age 9 years. Greater reading and writing time at ages 6 and 9 were associated with higher odds of myopia at age 9 (OR [95% CI] = 1.20 [1.02-1.42] and 1.11 [1.02-1.22] per h/day, respectively). Children spending >3 h/day reading and writing at age 9 had 76% higher odds of myopia than those spending ≤3 h/day (OR = 1.76, 95% CI: 1.08-2.85). Reading and writing time at ages 2 and 3 years, and screen time at all age groups showed no significant association with myopia at age 9.

Conclusions: Traditional paper-based reading and writing, but not screen time, were associated with myopia in Singaporean children. Future studies with larger samples and objective screen time measures are needed to evaluate the distinct role of screen time in myopia.