No screen time for children aged 0–3; limit it as much as possible for ages 3–6; for school‑age kids, non‑educational screen use should not exceed one hour per day

There is no monetary cost. The real challenge is keeping screens out of children’s hands and encouraging parents to cut down on their own screen time in front of them.

Article 4 of the “Ten Core Principles for Preventing Myopia in Children and Adolescents” states: “Children aged 0–3 should not use smartphones, tablets, computers, or other screen‑based electronic devices; children aged 3–6 should avoid such devices as much as possible; for school‑age students, non‑educational screen use should be limited to no more than 15 minutes at a time and no more than one hour per day.” It also notes that “prolonged close‑up use of screen devices can deplete a child’s far‑sightedness reserve, a key factor in the early and frequent occurrence of myopia.” In 2018, eight government agencies, including the Ministry of Education, issued similar recommendations, adding that “the younger the child, the shorter the recommended continuous screen time.” Scientific research is far less definitive: a systematic review examined 33 studies involving participants from 3 months to 33 years of age; only 11 contributed to the pooled analysis. When only smartphones and tablets were considered, the odds ratio for myopia was 1.26 (95 % CI 1.00–1.60, I² = 77 %). Including computers raised that figure to 1.77 (1.28–2.45, I² = 87 %). The authors concluded only that there may be a link, noting that none of the 33 studies measured screen time reliably.

国家卫生健康委办公厅 (2023). 防控儿童青少年近视核心知识十条（国卫办妇幼函〔2023〕278 号）. https://www.gov.cn/zhengce/zhengceku/202307/content_6894284.htm ; 教育部等八部门 (2018). 综合防控儿童青少年近视实施方案（教体艺〔2018〕3 号）. http://www.moe.gov.cn/srcsite/A17/moe_943/s3285/201808/t20180830_346672.html ; Foreman J, Salim AT, Praveen A, et al. (2021). Association between digital smart device use and myopia: a systematic review and meta-analysis. The Lancet Digital Health, 3(12), e806-e818. https://doi.org/10.1016/S2589-7500(21)00135-7 ; Madigan S, McArthur BA, Anhorn C, Eirich R, Christakis DA (2020). Associations between screen use and child language skills: a systematic review and meta-analysis. JAMA Pediatrics, 174(7), 665-675. https://doi.org/10.1001/jamapediatrics.2020.0327

Grade B because officials give tiered rules, not numbers from a trial. The lower bound of the research odds ratio sits at 1.00, and the authors only dare say “may be related.” Treat it as a household rule that is easy to run, not as “no screens means no myopia.” What has a lot-assigned trial behind it is item 4 (2 hours outdoors). Preschool eyes should also be checked. The same document says ages 1–3, 4–6, and after 7 should all have regular refractive screening to see how much hyperopia reserve remains. How to check is in item 12 (cycloplegic refraction). Screens and children’s language ability were also pooled in a meta-analysis of 42 studies with 18905 people. Longer screen time went with weaker language (r=−0.14, 95% CI −0.18 to −0.10). But co-viewing and educational content went the other way (r=0.16 and 0.13). That is association, not cause — it only shows that swapping screens for talking with the child is a poor trade.