The aim of this study was to gain a better understanding of how spending time outdoors can reduce the risk of developing myopia (near-sightedness). Previous research found that spending time outdoors can be protective against myopia, but the reason behind this is not well understood. This study investigated possible connections between myopia and ultraviolet B radiation (UVB) and vitamin D.
This study was based on data from over 3000 participants 65 years and older. The data included results from eye examinations, blood samples, interviews, and a written survey. The survey collected information about the participants' residence and employment history. Questions asked during the interviews focused on the participants' years of education, smoking and alcohol use, medical history, and diet. The survey and interviews also included detailed questions about time spent outdoors. While the survey was completed in advance, all other data was collected at six different eye examination centers in northern and southern Europe. Data about time outdoors included time spent outdoors between 9AM and 5PM and between 11AM and 3PM daily (from the age of 14) for different occupational and leisure periods, up to the participants' current age. Information about cloud cover and terrain around individual residences was gathered from published sources. The researchers used this information along with the geographical coordinates for participants' residence to generate estimates of individual years (from age 14) of all-day or middle-of-the-day exposure for different wavelengths of light.
Of the 3168 participants included in the final analysis, 371 had myopia. There were no differences found in the age or sex of people with or without myopia. Smoking habit, alcohol use, obesity, and dietary vitamin D intake were other factors showing no association with myopia. Significant differences were found between those with and without myopia in lifetime exposure to sunlight. The association between increased UVB exposure and reduced myopia was especially strong in adolescence and young adulthood. Participants who were exposed to the most sunlight -- particularly between the ages of 14 and 19 -- were about 25 percent less likely to have myopia by middle age.
The findings of this study are consistent with a growing body of research indicating that a lack of direct sunlight may reshape the human eye and impair vision. While more research is needed to examine the associations between sunlight and eyesight, more time outdoors during childhood and adolescence can be considered a possible strategy in the prevention of myopia.