Another useful focal point treatment is an undetectable color that squares bright (UV) light. Similarly as sunscreen keeps the sun's UV beams from hurting your skin, UV-defensive medicines for eyeglass focal points obstruct those same beams from harming your eyes. Overexposure to bright light is believed to be a reason for waterfalls, retinal harm and other eye issues. General plastic eyeglass focal points piece most UV light, yet including an UV-blocking color supports UV assurance to 100 percent for included security. Different eyeglass focal point materials, including polycarbonate and most high-file plastics, have 100 percent UV assurance worked in, so an additional focal point treatment isn't required for these focal points. Photochromic focal points additionally piece 100 percent of the sun's UV beams without the requirement for an additional UV focal point treatment. Photochromic Lenses.