The Properties of Transition Glasses

Transition glass was created in the 1960s by Corning. It only responded to UV rays, unlike transition glasses that now are more sensitive. The discovery was not widely integrated into glasses until photochronic plastic was created. In fact, transition glasses did not have wide distribution until 1991, when Transitions Optical Inc. released their patented transition lenses.

Photochronic Dye

• Photochronic dye is a dye that responds to UV rays. Light-sensitive elements such as argentic chloride and silver halide are incorporated into the dye. When sunlight interacts with the elements the glass darkens. When no sunlight is present, the glass does not darken. The dye transitions from dark to light more quickly than light to dark.

UV Protection

• Like sunglasses, transition glasses protect the wearer from UV rays. UV damage to the eye is similar to UV damage to the skin, causing conditions such as cataracts and the breakdown of the retina's macula, which affects vision in the center of the eye.

Glare Reduction

• Some photochronic lenses are also anti-glare, or polarized. Sunglasses reduce the entire surface of the lens equally. Polarized lenses selectively eliminate glare in the center of the lens.

Wavelengths

• The transition from light to dark was slower in original models, which only responded to UV rays. In 1996 and 2008, the technology was sped up by new research from Transitions Optical Inc. to the point of near imperceptibility. Newer models detect purple and blue light to offer more nuanced transitions in certain conditions, such as driving.