(plural) eyeglasses having two focal lengths, one for near vision and the other for far vision

An apparatus used to adjust the focal length of an optical system in order to make an image distinct or clear, Close or narrow attention; concentration, uncountable concentration of attention, transitive verb_ To bring to a focus; to focalize; as, to focus a camera, intransitive verb_ To direct toward a particular point or purpose, To adjust (a lens, for example) to produce a clear image

Of or relating to a focus, Placed at or measured from a focus, Belonging to, concerning, or located at a focus