Mirrored sunglasses have a thin metallic layer on the outside of the lenses that reflects glare away from the sunglasses rather than letting it in, reducing the amount of light entering the eyes. This makes them like one-way mirrors when observed from the outer side of the sunglasses. The lenses may look opaque due to the reflective coating, but they do let enough light through to help you see clearly with minimal eyestrain.

They are a great option for outdoor activities in very bright conditions where glare is a concern — for example, snow sports on a sunny day — as they can protect your vision by bouncing light rays off the lenses and away from your eyes.

Of course, protection ...