Myopia, or nearsightedness, is a refractive error, which means that the eye does not bend or refract light properly to a single focus in order to see images clearly. The disorder causes close objects to look clear but distant objects to appear blurred. It is the leading cause of visual impairment that affects on average 30-50% of adults in the United States and Europe. It can be inherited and is often discovered in children between the ages of eight and twelve. However during the teenage years, when the body grows rapidly, myopia may become worse. Patients with myopia have a higher risk of developing a detached retina, and a serious condition has a higher risk of developing glaucoma and cataracts.
Recently, a study has shown a possible link between the intensity of schooling and the onset of myopia. As societies have developed formal education systems, incidences of myopia has increased from around 1% to as much as 80- 90% in young adults. There is a direct correlation between rapid increases in the prevalence of myopia and rapid changes in access to education. An example of this is in East Asia after the Second World War and in China at the end of the cultural revolution.
Looking at East Asia in more detail, there has been a trend of increasingly early onset of myopia in the school years in East Asia This is probably due to early intense educational pressures such as homework at preschool level, combined with little time for play outdoors. As a result, almost 50% of children in East Asia are now myopic by the end of primary school, compared with less than 10% in the British ALSPAC study. The number of people affected by myopia is expected to increase from 1.4billion to 5 billion by 2050, based on existing trends. This would affect around half of the world’s population.
Whilst researchers have long been aware of the correlation between myopia and education, it has not been clear whether increasing exposure to education causes myopia, myopic children are more studious, or socioeconomic position leads to myopia and higher levels of education. However a new study by researchers at the University of Bristol and Cardiff University used a technique to Mendelian randomisation in order to prove the causation between myopia and education.