The invention refers to a pair of spectacles having a frame, the pair of spectacles comprising at least one switchable lens attached to the pair of spectacles, the at least one switchable lens configured to switch its foci from a far focal length to a near focal length, where the near focal length is smaller than the far focal length； an infrared emitter disposed at one side periphery of the at least one switchable lens and/or frame, the infrared emitter configured to emit an infrared radiation； an infrared sensor disposed at an opposite side periphery of the at least one switchable lens and/or frame, the infrared sensor configured to detect the infrared radiation from the infrared emitter； wherein the at least one switchable lens is configured to switch to its far focal length when the infrared sensor detects an intensity of infrared radiation that has been emitted and reflected off a front surface of a wearer's eye ball when the wearer is looking forward； and wherein the at least one switchable lens is configured to switch to its near focal length when the infrared sensor detects a different intensity of infrared radiation when the infrared radiation is changed in reflecting off the front surface of the wearer's eye ball by an upper eyelid of the wearer when the wearer is looking downward .
