Studies on visual health features of luminous environment in college classrooms

The light environments have an impact on the physiological and psychological environment by means of light and color to a certain degree, thereby affecting the visual health features. This study proposed to utilize a new index derived from clinical medicine, i.e., the root mean square contrast of ambient luminance to evaluate light environments. We explored the correlation among the RMS contrast and visual health features under non-glare conditions, so as to obtain the optimal luminance contrast range for visual health. We use visual task evaluation and physiological evaluation to represent visual health features. Eye-tracking glasses were utilized to record the physiological data of eyes, and the psychological software of E-Prime 3 was employed to record the efficiency data of visual tasks. Besides, the high dynamic range images were used to record light environment. The feasibility of the light environment evaluation by the RMS brightness contrast of the environment in the field of vision is verified experimentally. Through multiple regression analysis, an obvious relationship between the new index and the visual health features was obtained, and the best range of the new index was determined. The RMS contrast was typical within the range of [450,750] cd/m², which ensures the visual health for good ocular performance and high work efficiency; in the case that this value exceeds 1000 cd/m², visual health features will be adversely impacted. In this research, a comprehensive light comfort zone was proposed, which could present a valuable reference for the design of the indoor light environments.