US Patent 8012386 Method of manufacturing a lens presenting a graded tint

A method of manufacturing a lens presenting a graded tint, the lens comprising first and second layers each of which is made of a thermoplastic material, with only one of the layers being colored in the tint concerned, the method including the steps of:injecting the thermoplastic material of the first layer into a first mold cavity in order to form the first layer; andplacing the first layer in a second mold cavity and injecting therein the thermoplastic material of the second layer so as to form the second layer on the first layer.