Flash goggles were eyewear designed to provide normal vision in rapidly brightening and darkening light conditions, such as those caused by high-energy explosives or thermal detonators. Devoid of an energy source, and dependent on sensitive photocells and super-speed polarizing lenses, they could instantly dim and return to normal as required to prevent blinding or harm to the retinas of the wearer. They could alternately brighten, and allow the user to see in pitch darkness. Some models of flash goggles were more stylish, and resembled glareshades.