Adjustable focal length lenses and eyewear incorporating the same

Abstract

Adjustable focal length eyewear () comprising two lenses () that are mounted to a frame () for supporting the lenses () in front of a user's eyes. At least one of the lenses () is a variable focal length lens of the kind comprising two superposed lens elements () having cooperating optical surfaces that are shaped such that the focal length of the variable focal length lens () is variable according to the relative lateral disposition of the lens elements (). One of the lens elements () is fixedly mounted to the frame () and the other lens element () is movable manually relative to the fixed lens element () for varying the focal length of the variable focal length lens (). Guiding parts () are provided on the movable lens element () which cooperate with corresponding guiding parts on the fixed lens element () or the frame () to define and constrain movement of the movable lens element () relative to the fixed lens element () to a transverse path that extends across the viewing direction. One or more releasable fasteners are provided for releasably fastening the movable lens element () to the fixed lens element () or frame () whilst permitting movement of the movable lens element () relative to the fixed lens element () along the transverse path.