Assessment of daily light and ultraviolet exposure in young adults

There are some limited reports based on questionnaire data that suggest that outdoor activity decreases the risk of myopia in children and may offset the myopia risk associated with prolonged nearwork. The aim of this study was to explore the relationship between nearwork, indoor illumination, daily sunlight, and UV exposure in emmetropic and myopic university students-given that university students perform significant amounts of nearwork and, as a group, have a high prevalence of myopia.

Participants were 35 students, aged 17 to 25 years, who were classified as being emmetropic (n = 13) or having stable (n = 12) or progressing myopia (n = 10). During waking hours on three separate days, participants wore a light sensor data logger (HOBO) and a polysulfone UV dosimeter; these devices measured daily illuminance and accumulative UV exposure, respectively. Participants also completed a daily activity log.

No significant between-group differences were observed for average daily illuminance (p = 0.732), number of hours per day spent in sunlight (p = 0.266), outdoor shade (p = 0.726), bright indoor/dim outdoor light (p = 0.574), or dim room illumination (p = 0.484). Daily UV exposure was significantly different across the groups (p = 0.003), with stable myopes experiencing the greatest UV exposure (vs emmetropes, p = 0.002; versus progressing myopes, p = 0.004).

The current literature suggests that there is a link between myopia protection and spending time outdoors in children. Our data provide some evidence of this relationship in young adults and highlight the need for larger studies to further investigate this relationship longitudinally.