An artificial lens used in place of the eye's own crystalline lens, placed directly inside the eye and serving the same function. In addition to offering much improved vision, intraocular lenses have a more physiological refractive index than glasses or contact lenses, lowering the mental and physical stress on their owner. All AP members have intraocular lenses in their eyes to assist them in their work, which demands superior eyesight. It is said that intraocular lenses make the owner's eyesight 2 to 3 times more powerful than that of a normal person's, and they are also able to withstand any changes in water or air pressure. Originally developed to safeguard the eyesight of people working in extreme areas.