The Study
Myopia Progression Risk: Seasonal and Lifestyle Variations in Axial Length Growth in Czech Children
This study watched a group of kids over a year and noticed their eyes grew more in winter than in summer. It also saw that kids who spent more time on screens or sports had slightly different eye sizes at the start—but it didn’t prove that screens or sports made their eyes change. It just noticed a pattern.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
This study looked at how kids' eyeballs change size over a year and whether playing outside, doing sports, or reading too much affects it.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 545 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The seasonal difference is big and likely real — eyes grow more when days are short.
- 2But the lifestyle links are confusing: they show associations with pre-existing eye length, not changes during the study.
- 3In winter, 77% of kids' eyes grew longer; in summer, only 22% did.
- 4Kids who did more sports had shorter eyes to start with.
- 5Kids who read or used screens more had longer eyes to start with.
- 6Kids who spent more time outside also had longer eyes to start with.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Ophthalmology
Year
2018
Authors
S. Rusnak, V. Salcman, L. Hecova, Z. Kasl
Related Content
Claims (6)
Children who spend more than three hours a day playing sports have slightly shorter eyeballs on average than children who spend less than three hours a day in sports activity.
In 12-year-old children, the eyeball grows longer in winter than in summer, with most eyes showing growth during winter months and fewer during summer months in regions with large seasonal changes in daylight.
At age 12, children who spend more than three hours daily on close-up tasks like reading or screen use have longer eyeballs on average than children who spend less time on these tasks.
Over one year, children who spent more time on near-work, sports, or outdoors showed no measurable difference in the growth of their eye length.
Exposure to natural daylight increases dopamine release in the retina, which directly slows the lengthening of the eye and decreases the worsening of nearsightedness.
Children who spend more than two hours outside each day have slightly longer eyeballs on average than children who spend less than one hour outside, suggesting that eye length may influence how much time children spend outdoors rather than outdoor time changing eye length.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.