'Massive pressures'
Cultural factors also seem to play a part. Across many parts of South East Asia, children often have a lunchtime nap. According to Professor Morgan they are missing out on prime light to prevent myopia.
"Children suffer from a double whammy in South East Asia," says Professor Morgan.
"As a result of massive educational pressures and the construction of a child's day, the amount of time they spend outside in bright light is minimised."
