Blue light, part of the visible light spectrum, is emitted from the sun (the most powerful source of blue light), as well as artificial sources, including digital devices. While, even indoors, the sun is the largest source of blue light, blue light is also found in the LEDs of our domestic lighting and our screens, though the illumination levels are lower.

The visible light spectrum refers to a range of wavelengths, which include varying shades of red, orange, yellow, green, and blue light. The red end of the visible light spectrum has longer wavelengths of as high as 700 nanometers and relatively low energy levels.

At the opposite end of the spectrum is high-energy blue light with wavelengths as short as 380 nanometers and as long as 500 nanometers. Beyond visible blue light are ultraviolet (UV) rays, which cannot be seen by the eye, and have even shorter wavelengths and higher energy than blue light.

Foster Grant® blue light glasses and reading glasses help filter blue-violet light*. Additionally, all blue light styles have 100% UVA-UVB lens protection.

*Filters at least 30% of blue-violet light. The percentage refers to the average amount of blue-violet light (between 400-455nm as stated by ISO TR 20772:2018) filtered as measured in 5 nm increments. Covered under U.S. Pat. No. 8,360,574. Other U.S. and foreign patents pending.