When choosing a sunglasses shape, you need to consider your fashion preference, face shape, and the end use. In terms of face shape, some general guidelines might help you narrow down your choices:
For those who spend a lot of time on water or driving, polarized lenses provide another layer of clarity, as they reduce the glare coming from flat roads and smooth water. The special filter on polarized lenses blocks this intense, reflected light. Enjoy your outdoor activities more with polarized lenses.
Thinner and lighter than traditional plastic, polycarbonate is also more impact-resistant than traditional plastic. Developed for aerospace applications, polycarbonate is currently used in astronauts' helmet visors and space shuttle windshields. The properties of polycarbonate make these types of glasses ideal for your outdoor activities.
Sunglass Ultraviolet Protection:
In the United States, the amount of ultraviolet (UV) radiation reaching the ground is calculated from 290 to 400 nm in wavelength (representing the full spectrum of UV wavelengths). Sunglasses that offer UV absorption up to 400 nanometer (nm), block at least 99% of UV rays. These are sometimes listed as 400 UV sunglasses.