Can what children eat stop short sight getting worse? In 204,238 pupils, diet barely moved the needle; time outdoors and where they lived did more

Short sight in children is usually treated as a matter of glasses. The worry for eye doctors is what happens when it keeps getting worse. Once a child's prescription passes −6.00 dioptres, the cut-off for 'high myopia', the eyeball has stretched enough to raise the lifetime risk of retinal detachment, glaucoma and other sight-threatening problems. A team at Tianjin Medical University Eye Hospital has used the city's school eye-screening programme to ask which children make that slide, and whether diet has anything to do with it. Their paper was published in the Journal of Global Health on 2 October 2026.

They followed 204,238 pupils in grades 1 to 9 who were already short-sighted, but not severely, from 2021 to 2024, with eye checks every semester in primary school and yearly in secondary school. Parents and children answered a questionnaire at the start about time outdoors, close reading and food, and the researchers sorted the answers into three eating patterns: 'energy-dense', 'plant-based' and 'traditional nutrient-rich'. They also scored each district's wealth and spending on schools and health, and measured how green the land around each school looked from satellites. Over the four years, 26,879 children (13.2%) reached high myopia.

Diet came out as the weakest of the factors they looked at. Compared with the energy-dense pattern, a plant-based one went with a 3% lower risk (hazard ratio 0.97), right at the edge of statistical significance; in a sensitivity analysis with more adjustment it became 6%. The traditional pattern made no clear difference in the main analysis. Spending more than two hours a day outdoors went with an 8% lower risk, and the benefit looked largest in children aged 6 to 12. The biggest gap of all was between districts: children in the poorest third of Tianjin's districts were 54% more likely to reach high myopia than those in the richest, and children in greener school surroundings did a little better too. Oddly, outdoor time seemed to help less in the poorer districts.

This is an observational study, so it shows links rather than causes, and the diet measure is its weak point. The paper doesn't spell out what foods each pattern contained (that sits in a supplement), the answers were given once and reported by families, and diet in children travels with family income, schooling pressure and screen time, which are hard to separate. Wealth and greenness were scored for whole districts and school neighbourhoods, not for each family. Some numbers in the tables don't quite add up to the full group, which suggests not every child was counted in every analysis. What the study does add is scale: a city-wide cohort, a hard clinical end point, and a reminder that for children's eyes the strongest evidence is still for getting them outside, as an earlier school trial in Guangzhou showed. A plant-rich diet is worth having for many reasons; on this evidence, saving a child's eyesight isn't the main one.