School Experiences by Grade, Not Age Related to Myopic Shifts in Children

Exposure to schooling has a greater effect on refractive development in children than age itself, according to a study published in Investigative Ophthalmology and Visual Science. 

Researchers conducted an analysis of 706 grade 1 students (mean age 6.56±0.29 years, 55% boys) from the control group of the Guangzhou Outdoor Activity Longitudinal Trial (Clinicaltrials.gov Identifier: NCT00848900). They stratified participants into 3 groups based on month of birth (Group 1: May-August 2003, Group2: January-April 2003, and Group 3: September-December 2002) and conducted yearly cycloplegic examinations on the cohort until grade 4. 

Researchers did not observe any significant differences in spherical equivalent (SE) between age blocks within the same grade (all P >.05). However, comparisons between grade levels yielded significant spherical equivalent (SE) differences — even between the youngest group of a higher grade, and the oldest group of the preceding grade. Investigators noted greater myopic SE differences between the youngest block of grade 2 compared with the oldest block of grade 1, the youngest block of grade 3 compared with the oldest block of grade 2, and the youngest block of grade 4 compared with the oldest block of grade 3 (-0.36±0.08 D, -0.50±0.10 D, and -0.82±0.14 D, respectively, P <.001 for all).   

“The myopic shifts in refraction associated with years of schooling vary depending on the level of schooling and accelerate in the Chinese education system through the early primary years before declining later, despite likely increases in educational pressures and greater deprivation of time outdoors because refractive plasticity declines with age,” according to the researchers. They also suggest changing the organization of the school day “to minimize educational pressures and maximize opportunities for time outdoors, while maintaining crucial parts of learning in the early school years,” to combat rising cases in myopia.

The study is limited by the failure to observe myopic shifts past grade 4 and failure to account for potential confounding factors caused by month or season. 

Reference

Ding X, Morgan IG, Hu Y, Yuan Z, He M. Exposure to the life of a school child rather than age determines myopic shifts in refraction in school children. Invest Ophthalmol Vis Sci. 2022;63(3):15 doi:10.1167/iovs.63.3.15