Edge filters are special filters that filter out UV light and blue light of short wavelengths
. They have two more or less sharply separated spectral ranges: one spectral range is transmissive (transmitting), the other is opaque (absorbing). The transmission and absorption ranges are separated from each other by a steep slope. Depending on the characteristic, the absorption range already begins at wavelengths in the green range and extends to ultraviolet. Such optical filters
are used in eyeglasses of patients with eye diseases and are supposed to protect the eyes from short-wave light.