a lens has two or more layered sections of thermoplastic material , and a substantially homogenous formation in which at least one of the layered sections has an active photochromic material present . the article is made by : forming a mould cavity from first and second mould halves ; loading the mould cavity with a first thermoplastic material ; curing or partially curing that material ; changing the second mould half to define a subsequent mould cavity in which the cured or partially cured material is present ; loading the subsequent mould cavity with a subsequent thermoplastic material ; and completing any uncompleted curing of the first and subsequent thermoplastic materials . at least one of the thermoplastic materials is loaded with an active photochromic material .