The more years you spend in full-timeeducation, the more short-sighted you are likely tobe, according to a large UK study.

The link appears to be that students have toolittle exposure to bright natural light - and theantidote suggested by the researchers is for childrento spend more ofthe day outdoors.

The study, carried out by Cardiff and Bristoluniversity scientists, analysed information on thegenetics, eyesight and educational background of68 000 participants in the UK Biobank database.

The findings, published in the BMJ, implythat a graduate who spent 17 years in educationis on average one dioptre more short-sighted thatsomeone who left school at the age of 16 afterspending 12 years in education.

That deterioration is equivalent to thedifference between having perfect vision andneeding glasses to drive safely.

"With the rapid rise in the global prevalenceof myopia and its vision-threatening complications,together with the economic burden of visual loss, thefindings of this study have important implicationsfor educational practices," said Jez Guggenheim, ofCardiff University's School of Optometry and VisionSciences.

Using Biobank data, the Bristol and Cardiffscientists analysed 44 genetic variants associatedwith risk of myopia and 69 variants associated withtime spent in education.

They found that while the number of yearsat school and college strongly influenced eyesight,there was no effect in the opposite direction:propensity to myopia did not lead people to remainin education for longer.