Abstract: A time-temperature indicator device for recording the duration of time over which a temperature has been established above a predetermined temperature, which device includes a dye-compatible polymer composition having a softening point above the predetermined temperature and a polymer-compatible dye composition in contact with the polymer composition and present in a quantity with respect to the polymer composition sufficient for diffusion through the polymer composition whenever the polymer composition is above the predetermined temperature, which quantity is selected so that the extent of diffusion corresponds to the duration of exposure above the predetermined temperature relative to the total time required for substantially complete diffusion. Articles for which a heat history above a predetermined temperature is to be record, in combination with the disclosed time-temperature indicator devices are also described.

Abstract: A prepolymerization step prior to casting reduces shrinkage during polymerization of a composition containing diethylene glycol bis(allyl carbonate) with up to 40% of a vinyl ester, preferably vinyl acetate, and one or more free radical type initiators. The prepolymerization step includes adding a small amount of free radical type initiator, which may be the same or different than that used just prior to casting, and heating to a temperature higher than one hour half-lifetime temperature of the initiator. In this manner, most of the added initiator is consumed and the prepolymerization produces the highest possible conversion while preventing overpolymerization. High yield of lenses of ophthalmic quality is obtained.

Abstract: The combined contact lens is characterized in that it comprises a zone of a hydrophilic material, an aperture in the center of said zone, and a solid body from an optically transparent material fixed in said aperture, said solid body being made in the form of a rod bonded chemically with said zone.In the method for the manufacture of the combined contact lens, a hydroxyl-containing monomer is polymerized in the presence of an agent initiating polymerization, a solvent, and a linking agent, inside a mould provided with a rod located in the center of the mould and made from a polymer that is inactive toward water but swells in the solution of the starting hydroxyl-containing monomer.The invention provides good toleration of the lens with the patient and ensures optimum optical effect with various abnormalties of refraction and in various pathological states of the cornea.