Abstract: A process of integrating a photochromic substance, especially a spiropyran or a metal dithizonate, into a transparent substrate of polymerized organic material such as poly [ethylene glycol di-allyl di-carbonate] by thermal transfer, comprising applying the photochromic substance alone or with a solvent and/or thickening agent to the surface of a transparent organic substrate such as a lens disc, and heating until the photochromic substance is sublimed and then diffused and anchored in the organic material of the lens, preferably just beneath the surface to which it is applied. Preferably, the photochromic substance is initially carried on a temporarily support for application.

Abstract: A method of marking an ophthalmic lens of organic material and the lens so marked. A marking substance containing an optical brightener which is a derivative of benzoxazolyls stilbenes, or benzotriazoles is mixed with a suitable binder and solvent and applied to a surface of the lens to be marked by thermal transfer from a transfer support. The marking substance is shaped to the desired configuration either when applied to the transfer support or by a mask defining the mark or indicia to be applied. Heat is applied to the marking substance and the lens which sublimes the optical brightener which then penetrates into the organic material of the lens to be anchored therein. The resultant indicia or mark provides a permanent marking of the lens and is only visible in ultra-violet light.