Do green-blocking glasses enhance the nonvisual effects of white polychromatic light?

BackgroundIt is well known that light containing the blue component stimulates the intrinsically photosensitive retinal ganglion cells (ipRGCs) and plays a role in melatonin suppression and pupillary constriction. In our previous studies, we verified that simultaneous exposure to blue and green light resulted in less pupillary constriction than blue light exposure. Hence, we hypothesized that the nonvisual effects of polychromatic white light might be increased by blocking the green component. Therefore, we conducted an experiment using optical filters that blocked blue or green component and examined the nonvisual effects of these lights on pupillary constriction and electroencephalogram power spectra.MethodsTen healthy young males participated in this study. The participant sat on a chair with his eyes facing an integrating sphere. After 10min of light adaptation, the participant's left eye was exposed to white pulsed light (1000lx; pulse width 2.5ms) every 10s with a blue-blocking glasses, a green-blocking glasses, or control glasses (no lens), and pupillary constriction was measured. Then, after rest for 10min, the participant was exposed a continuous white light of 1000lx with a blue- or green-blocking glasses or control glasses and electroencephalogram was measured.ResultsPupillary constriction with the blue-blocking glasses was significantly less than that observed with the green-blocking glasses. Furthermore, pupillary constriction under the green-blocking glasses was significantly greater than that observed with the control glasses.ConclusionsA reduction in the green component of light facilitated pupillary constriction. Thus, the effects of polychromatic white light containing blue and green components on ipRGCs are apparently increased by removing the green component.