Abstract: The focus of variable-focus lenses in eyeglasses worn by a person is regulated in accordance with an indication of a spatial relationship of features of the person's eyes to provide an at least partially in-focus image of a feature at which the person is gazing.. The lenses are nematic liquid crystal display devices. Light reflected off of each of the person's eyes is detected to provide data indicating the respective dispositions of the person's eyes; and the combined data for both eyes is processed by a neural network in a computer to provide focus-control signals for setting the focus of each lens.