Penn Science Teacher Institute

Photochromism has been observerd as early as 1867. J. Fritzsche noted the bleaching of orange tetracene in sunlight. E. ter Meer noticed that potassium dinitroethane changed from yellow to red when exposed to light in 1876. In 1881, T. Phipson saw that a painted black post turned white at night. The most notable early researcher of photochromism was W. Markwald, though. He studied the color changes of 2,3,4,4-tetrachloronaphthalen-1(4H)-one in 1899. Since he thought the color change was of a physical nature, he named the color-changing process phototropy. The study of photochromism resumed in Israel in 1950. Yehuda Hirshberg came up with the term "photochromism" to describe the color change associated with light (Bouas-Laurent & Durr).

Corning was the first company to introduce photochromic lenses. In 1964, their photochromic glass lenses using silver hit the marketplace. The silver was dispersed evenly throughout the glass medium. Eventually, Corning also came out with an organic photochromic line of lenses. The organic dyes could be evenly mixed throughout the plastic or thinly coated on the surface of the plastic (Photochromism Corning).

Trasitions® lenses were introduced in 1990. Between 1991 and 2002, the company released four generations of photochromic lenses. The Generation 5 lenses, introduced in 2005, claimed to be clear indoors and as dark as sunglasses outdoors. In 2008, Generation 6 lenses were released. These lenses boasted faster transition times (Company History).