Lenses may be mounted to eyewear using several techniques. A first technique involves the use of a lens unit that is mounted to a frame at a frame bridge. The lens unit includes a lens frame split proximate to the frame bridge, allowing the frame to be opened and a lens inserted. A second technique involves a mechanical interference arrangement that allows a lens to be inserted into, and retained by, a frame groove in a front frame. An inner cover may then be affixed to the front frame to enclose electronics in the front frame.