An analysis of light that reaches the eye surface in an outdoor environment

The global pandemic of myopia has become an urgent public health concern in recent years. Although the mechanism remains largely unclear, the importance of outdoor light exposure on myopia prevention is widely recognized. Outdoor light is more intense and has a different spectral composition compared to indoor lighting, which are believed to contribute to the suppression of myopia. However, due to modern lifestyles, even children find it difficult to spend time outdoors. To receive outdoor light efficiently is important, yet previous reports showed inconsistent findings on optimal thresholds for outdoor light exposure. One reason may be the lack of a standardized protocol for measuring light reaching the eye surface. In this study, we developed a novel measurement device using a 3D-printed mannequin head with a light sensor probe embedded at the eye position to mimic the human eye. We assessed the proportion of light that reached the mannequin's eye surface from different directions at various time points on a sunny day and evaluated the influence of different eyeglasses and lenses.