Blu-ray is part of natural visible light, and both daylight and electronic screens emit blue light. Blue light is an important part of visible light. There is no single white light in nature. Blue light is mixed with green light and red light to produce white light. The green and red light energy is small, the eye is less irritating, the blue light wave is short, the energy is high, and the lens can directly penetrate the lens to the macular area of the eye, resulting in macular degeneration.