A fashion tint is a permanent tint added to a lens. A fashion tint does not increase in darkness when outside or lighten when inside. Fashion tints can be solid (same degree of tint from the top of the lens to the bottom of the lens) or gradient (the tint fades from a dark tint at the top of the lens to clear at the bottom of the lens). Fashion tints can be brown, dark green or gray and can be done in grades 1-3, with grade one being the lightest and grade 3 being the darkest and intended as a sunglass tint.

Low index (plastic) lens materials accept tint the best and will achieve a grade 3 tint better than mid or hi index lens materials.

A polarized lens is a type of sunglass lens that always remains dark and does not lighten when indoors. Polarized lenses contain a tinted filter that cuts down the glare caused by light reflected off of surfaces like water and the roadway. Outdoor enthusiasts like fisherman, snow skiers, and bikers will enjoy the clarity and reduced glare these lenses offer.

Transition lenses darken in the presence of ultraviolet light (UV) from the sun and then lighten up to a clear lens when not in the presence of any UV light. Transition lenses work great for people who want the benefit of sunglasses outdoors, without the hassle of keeping up with a second pair of prescription sunglasses.

Transition lenses darken the best and also return to clear the fastest in a low index (plastic) lens material. Mid and hi index lenses can be made as transition lenses but these lens materials will not darken as much as a low index lenses. Mid and hi index lenses will take a few moments longer to lighten back up to clear.

It is important to note that UV light is a high energy wavelength light and it is easily reflected off of your car’s windshield. While low energy infrared light (heat) will easily pass through your windshield, most UV light will simply bounce off of your windshield and be reflected back into the atmosphere. This characteristic of UV light results in transition lenses only darkening slightly while you are inside of your car.

It should also be noted that transition lens materials do not immediately lighten to clear when exiting UV light. The lightening time can vary depending on the lens material, the amount and length of UV exposure, and the surrounding temperature. Typically, all transition lenses will return to clear in less than 2 minutes of leaving a UV exposed environment.

Many consumers have noted that transitions lenses work very well for the first two years, but then do not darken as effectively after 2 years of wear. If you want transition lenses to achieve maximum darkening then the lens material may have to be replaced about every 2-2.5 years.