Polarized sunglasses protect eyes by reducing glare, particularly on the water. These sunglasses help to filter out the light that comes off of surfaces such as water or pavement, which keeps harmful glare from the sun out of the eyes and reduces sun-related squinting.
Although their job is to reduce glare from the sun, polarized lenses are not the same as lenses with UV protection. For this reason, consumers should check that the sunglasses also offer complete UV filtering for optimal protection. Some polarized lenses are made with a specific UV-blocking substance. Aside from blocking brightness from sun rays, polarized glasses also increase contrast, which allows the person wearing them to see objects more accurately. To specifically keep glare from reflecting back into the eyes, polarized lenses cut down on horizontal wavelengths, which create glare, while enabling essential vertical wavelengths to pass through.
An optimal pair of polarized sunglasses has lenses with a durable surface that is hard to break, such as polycarbonate. Ideally, the lenses should also absorb 99 to 100 percent of the three types of UV rays. Non-polarized lenses of similar or the same quality may offer the same protection against UV rays, but they do not offer the same protection against the sun's glare.