Quality sunglasses should block 99-100% of both UVA and UVB radiation. UVA affects deep eye tissues while UVB primarily damages the cornea and lens.

Look for sunglasses labeled 'UV400' or '100% UV protection.' This ensures they block all light rays with wavelengths up to 400 nanometers, covering all UVA and UVB rays.

Lens color doesn't determine UV protection. Dark lenses without UV protection can be more harmful than no sunglasses at all, as they cause pupils to dilate, allowing more UV rays to enter.

Wrap-around sunglasses or those with larger frames provide better protection by blocking UV rays from entering from the sides, reducing the risk of eye conditions like cataracts and macular degeneration.

Polarized lenses reduce glare but don't necessarily provide UV protection. Always check for specific UV protection features, as polarization alone doesn't protect against harmful rays.

UV rays can damage eyes year-round, even on cloudy days. Snow can reflect up to 80% of UV rays, increasing exposure. Wearing sunglasses during winter activities is just as important as in summer.