A pair of spectacles has a frame and defines a horizontal plane generally through the temples and bridge of the spectacles. At least one switchable lens is configured to switch its foci from a first focal length to a second focal length. An infrared emitter is disposed at one peripheral edge of the at least one switchable lens, the infrared emitter configured to emit an infrared radiation. An infrared sensor is disposed at an opposite peripheral edge, the infrared sensor configured to detect a different intensity of the infrared radiation from the infrared emitter upon reflection from the front surface of wearers eye ball. The at least one switchable lens is configured to switch to its first focal length when the infrared sensor detects the infrared radiation and is configured to switch to its second focal length when the infrared sensor detects a different intensity of the infrared radiation.
