If you have eye sensitivity or work both indoors and outdoors throughout the day, you may want to use photochromatic, tinted or polarized lenses.
Photochromic Lenses
Photochromic lenses will lighten and darken depending on the availability of ultraviolet light. Photochromic lenses are best for comfort and are not a substitute for safety sunglasses. Direct sunlight and UV rays trigger the photocromic lens to get dark, so they will not change in the car, since all windshields come with a UV blocker.
Tinted Lenses
A colored tint will permanently tint the lenses of your glasses. Plastic and glass lenses can be tinted to practically any color you want, although a lighter tint is primarily to enhance the style and look, while a darker tint is for use in bright lighting.
Polarized Lenses
Polarized lenses will reduce glare through special polarized filters and also provide 100% UV protection. Polarzied lenses are the ultimate in visual clarity and depth perception when faced with reflective materials such as water, vehicles and snow.