Patent attributes
Described herein is a method for producing photochromic contact lenses, in particular, photochromic silicone hydrogel contact lenses. The method comprises a step of cast molding of a lens-forming composition including a vinylic monomer having a primary amino or thiolactone group to form an unprocessed contact lens having the polymer matrix of which have pendant primary amino or thiolactone groups, a step of one-pot multistep reactions based on thiolactone chemistry (aminolysis and thiol-induced graft polymerization of a photochromic vinylic monomer to the polymer matrix) which are carried out only in its central region which is circular and concentric with the central axis of the unprocessed contact lens. The obtained photochromic contact lens has a central pupillary region that only can undergo a reversible color change upon exposure to UV/HEVL-radiation.
