It is far more common to be nearsighted today than ever.
According to a study by the National Eye Institute, the occurrence of myopia in America, which is the medical name for the condition, has soared by 66 percent since the early 1970s. Even more surprising is the fact that in China and other East Asian countries, as many as 90 percent of recent high school graduates are thought to be nearsighted.
Nearsightedness or myopia occurs when the eyeballs are longer than normal. This changes the angle at which light enters the eye and negatively affects the ability to focus on distant objects. Myopia usually begins before adolescence when the eye is growing and involves a complex interplay of genetics and environment. This condition often worsens during early adulthood.
Many make the assumption that the elevated rates of myopia are related to the many hours young people stare at computers and other screens. However, a recent study published in JAMA Ophthalmology suggests that a greater factor may be a side effect of all that screen-watching; today’s children spend much more time indoors. A growing body of research indicates that the shape of the human eye can be influenced by a lack of direct sunlight.
At King’s College London, the London School of Hygiene and Tropical Medicine and other institutions, researchers provided vision exams to more than 3,100 older European men and women. They also asked them about their education, careers and how often they remembered being outside during various stages of their lives. The researchers took the information and cross-referenced it with historical data about sunlight.
The researchers found strong correlations between current eyesight and volunteers’ lifetime exposure to sunlight, above all UVB radiation (which is responsible for burning). The study participants who had been exposed to the most sun, particularly between the ages of 14 and 19, were approximately 25 percent less likely to have developed myopia by middle age. They found that exposure to sunlight up to the age of 30 also provided a protective benefit.
The study was not a true experiment, so it could not determine whether too little sunlight actually causes myopia, nor could it explain the connection. However, one researcher concluded this: “People with myopia have long eyeballs, so there must be something in sunlight that affects how the eye grows, especially in childhood.”
Sunlight can also have harmful impacts on the eyes. Sun exposure can increase the risks of developing cataracts. It is believed that by taking the appropriate cautions, including the avoidance of midday sunlight, young people should be able to reduce those risks while potentially bolstering their vision. The researchers found that there is definitely something in today’s childhood that is causing a massive rise in the number of people that are nearsighted, and they feel that the lack of time outdoors is a contributing factor.
Adapted from New York Times and Journal of the American Medical Association (JAMA).