Methods and apparatus are disclosed for the manufacture of plastic intraocular lenses of the type used for transplant in the human eye for natural lens replacement in cataract surgery. The novel methods and apparatus of the present invention are characterized in that the lines or wires used as retention loops are attached to the plastic lens bodies by fusing the ends thereof internally of the lens body in a position remote from the outer peripheries of the lens bodies but outside the central areas of vision of the lens bodies, one method of fusing the ends of the wires to the lens bodies being by heating the wires and pushing them into the lens bodies.