University of Utah engineers have created ‘smart glasses’ with liquid-based lenses that can automatically adjust the focus on what a person is seeing, whether it's far away or close up. The human eye has a lens inside that adjusts the focal depth depending on what you look at. As people age, the lens loses its ability to change focus, which is why many people require reading glasses to see objects up close and regular eyeglasses to see far away. The researchers created eyeglass lenses made of glycerin, a thick colorless liquid enclosed by flexible rubber-like membranes in the front and back. The rear membrane in each lens is connected to a series of three mechanical actuators that push the membrane back and forth like a transparent piston, changing the curvature of the liquid lens and therefore the focal length between the lens and the eye. The lenses are placed in special eyeglass frames with electronics and a battery to control and power the actuators. In the bridge of the glasses is a distance meter that measures the distance from the glasses to an object via pulses of infrared light.