in a method of producing an intraocular lens having a substantially clear optic and at least one filamentous haptic having high fracture toughness , solid particles are mixed into an uncured polymer , and the mixture is inserted into a mold . ultrasonic energy is applied to the mold until the mixture solidifies . heat is applied to complete the curing process . ultrasonic energy is also preferably applied to the particles and uncured polymer mixture to improve dispersion of the particles therein .