So, what are we looking at? To start, the wavelength of visible light is between 380-780nm. High energy visible light (HEV) is between 380-500nm and may cause damage to your eyes. HEV light includes blue-violet light (between 400-455nm as stated by ISO TR20772-2018), which can be potentially harmful to your eyes over a cumultive period of time, and blue-turquoise light between 460-500nm, a major synchronizer of biorhythms. The most powerful source of blue-violet light is the sun, by far, even indoors through windows. Blue light filtering glasses help to preserve visual comfort.