The darker the eyeglass lenses, the better they protect your eyes from the sun. Is this true? Although it sounds logical, it's false.

"The degree of tint has no relation to the degree of protection from harmful ultraviolet (UV) radiation," says Sarah Koester, spokeswoman for the Dusseldorf-based Central Association of Opticians and Optometrists (ZVA). Like UV radiation, UV filters are invisible.

There are clear lenses with UV protection. Meanwhile, dark-tinted lenses without a UV filter can actually do more harm than good, Koester warns.

Because they let through less light, your pupils dilate, allowing even more UV radiation to reach the eye's cornea, lens and retina.

Generally speaking, you can prevent light-related damage to your eyes with eyeglass lenses having a tint and/or filter coating, notes optician Peggy Kleindienst, who says they protect against things such as UV radiation in sunlight, glare, diffuse light and infrared radiation.

Certain occupational groups, such as welders, have to wear goggles or safety glasses with a filter coating to protect against radiation that can damage the eyes. Welding arcs, for example, emit UV and infrared radiation.

"And people with eye diseases can achieve better contrast vision and alleviate their symptoms by wearing special filter glasses," Kleindienst adds.

There are various kinds of filters for eyeglasses: