Sun glasses are a visual aid, variously termed spectacles or glasses, which feature lenses that are coloured, polarized or darkened to prevent strong light from reaching the eyes, where as, Goggles or safety glasses are forms of protective eyewear that usually enclose or protect the eye area in order to prevent particulates, water or chemicals from striking the eyes. They are used in chemistry laboratories and in woodworking. They are often used in snow sports as well, and in swimming. Goggles are often worn when using power tools such as drills or chainsaws to prevent flying particles from damaging the eyes. Many types of goggles are available as prescription goggles for those with vision problems.