Polarised sunglasses were first invented by Polaroid in 1935. It’s why a lot of people still use the term ‘Polaroid lenses’ when then mean ‘polarised lenses’.
Polarised lenses are different to standard sunglass lenses; they have a special film which helps eliminate glare reflected off a surface like a pavement, road, water or snow. One of the questions we are often asked is “Do all polarised sunglasses stop glare?” The simple answer is yes. However, there is a difference between a £20 pair of polarised sunglasses and a £70+ pair. On lower cost polarised sunglasses, the polarised film is applied to the front of the lens. In time, this can scratch and wear down meaning the sunglass will lose some of its anti-glare effectiveness. On the more expensive polarised sunglasses the film will be sandwiched between two other layers (usually polycarbonate) meaning the film can never wear out or lose its effectiveness.
On less expensive polarised sunglasses, the lens material used is likely to be TAC which is typically 1mm or 1.2mm in thickness. This means they should not be used where impact protection is required. On the higher priced polarised the lens material is likely to be polycarbonate and a polarised polycarbonate lens also provides impact protection.