Another beneficial lens treatment is an invisible dye that blocks ultraviolet (UV) light. Just as sunscreen keeps the sun's UV rays from harming your skin, UV-protective treatments for eyeglass lenses block those same rays from damaging your eyes.

Overexposure to ultraviolet light is thought to be a cause of cataracts, retinal damage and other eye problems.

Regular plastic eyeglass lenses block most UV light, but adding a UV-blocking dye boosts UV protection to 100 percent for added safety. Other eyeglass lens materials, including polycarbonate and most high-index plastics, have 100 percent UV protection built-in, so an extra lens treatment is not required for these lenses.

Photochromic lenses also block 100 percent of the sun's UV rays without the need for an added UV lens treatment.