It’s the time of year when festivals and carnivals and street parades are going on around the Western Hemisphere, and there’s been a new fashion accessory that’s appeared on the bouncers and first aid staff who keep these events safe – safety glasses.

Not those clunky old things you had to wear in school science lessons, but cool, stylish glasses that look like top of the range sunglasses but act to protect the eyes from assault, whether that’s beer being thrown by rowdy festival-goers or the effects of sun and rain, or even being punched by somebody who’s lost the plot of being out without being a nuisance.

Safety glasses are based around shatter-resistant plastic lenses which are specially designed to protect eyes from flying debris and they vary in the amount of protection they provide. Nylon frames are usually used too, for the same reason they are used for sports eyewear: because they are lightweight and flexible, which means they bend, rather than breaking, when pressure is applied to them.