"Ashby attempted to induce myopia in a group of chicks by blurring their vision using special lenses. He divided the birds into three groups and exposed them to different light levels for just 15 minutes each day. At the end of the five-day trial, those exposed to intense light - half as bright as direct sunlight and 30 times brighter than normal indoor lighting - were on average 40 per cent less short-sighted than chicks exposed to normal laboratory light levels during those 15 minutes. Actual daylight slashed the severity of myopia by a further 40 per cent (Investigative Ophthalmology and Visual Science, DOI: 10.1167/iovs.09-3419)." - Björn Brembs from Bookmarklet