Students experience a marked decline in eyesight while at university, with too much "intensive" reading to blame, a study suggests.
Long hours of study put stress on the eye
Researchers at Spain's Complutense University found 31.3% of first-years were short-sighted.
Among those four to six years older, in their final year, the rate was 49%.
Research author Dr Rafaela Garrido said many of the 270 students tested spent up to 10 hours at a time reading in poor light.
'Dealing with the stress'
She told BBC News Online: "Some students are spending too long in intensive near work with their eyes.
"It is also a problem with people who spend too long on a computer or using a microscope.
"It's difficult to ask students to do less reading, as it is essential to passing courses, but we have to find ways to deal with the stress on the eyes."
Research is being carried out into lenses to prevent myopia among those involved in intensive reading or screen-viewing.
Some scientists have tested drugs to delay the onset of short-sightedness by relaxing the eye during periods of intensive work.
Dr Garrido said most sufferers who developed the condition while children had a genetic tendency towards it.
Adults, however, were likely to become short-sighted because of too much stress on the eye.
Dr Garrido said: "There are some things students and others can do to prevent myopia.
"Having good light and taking regular study breaks are among them.
"We have to find another way to prevent the onset of myopia."
Dr Garrido is presenting her findings to the 10th International Myopia Conference in Cambridge.