Lightstruck, or "skunked" or "skunky", beer has been exposed to ultraviolet and visible light. In some cases, such as Miller High Life, a hops extract that does not have isohumulones is used to bitter the beer so it cannot be "lightstruck", and there are also other solutions available to prevent beer bottled in clear and green glass from becoming skunked or light-struck, such as taller walls on 6-pack carriers.