the invention relates to photochromic transparent organic materials particularly useful for the production of photochromic organic ophthalmic lenses . the material includes an optical - quality polymer matrix and at least one coloring agent giving photochromic properties to the matrix . the coloring agent is chosen from the group of the spirooxazins the spiropyrans , and the chromenes . the polymer of the matrix is chosen from the group of homopolymers of ethyoxylated bisphenol a dimethacrylate with formula i : in which r is h or ch 3 , and m and n independently represent 1 or 2 , and of the copolymers of this dimethacrylate containing at most 30 wt % of an aromatic monomer with vinyl , acrylic or methacrylic functionality .