Abstract: The study aims to investigate the effect of color temperature of tunnel LED light source on pupil diameter, variation ratio of pupil area and reaction time during the dark adaptation through visual performance experiments. Results show that the process of dark adaptation can be divided into two stages, namely, the early stage and the middle-late stage. The early stage lasts about 2s, during which the variation ratio of pupil area exceeds 70% frequently and the blinking frequency rises up to 1.7times/s. The middle-late stage lasts about 20s, during which the variation ratio of pupil area remains in the range of ±4% and blinking frequency returns to normal level. The higher color temperature of LED light source is, the smaller pupil area, lower visual load and faster reaction time is during the early stage. Intermediate color temperature gives rise to a relatively higher visual performance during the middle-late stage. Accordingly, the recommended color temperature of LED light source in threshold zone and transition zone was proposed.

Key words: LED, color temperature, dark adaptation stage, visual performance, eye movement characteristic