The e-glasses will be available in a range of colors and styles, including wire, plastic, and rimless frames. By touching a button on the side of the frames, you go into close-up mode. Tap again to look across the room, with less distortion than is typical with Unlike traditional bifocals, which only have near and far vision, the e-glasses also have a mid-range mode.
They’re made of liquid crystal, embedded between standard plastic lenses. “When an electrical charge is applied to the liquid crystal zone, it changes the strength of the prescription, so the wearer can focus on objects at various distances.” The spectacles are powered by a rechargeable battery concealed in the frame.
Bifocals typically are placed so the line rests at the same height as the wearer's lower eyelid.
As a bifocal wearer drops his eyes downward to read, the eyes naturally seek out the near-vision portion of the lens.
Bifocals and trifocals have visible lines, but the line in a round-seg bifocal tends to be less noticeable than the lines in flat-top and Executive styles.
There is something called an "invisible bifocal," which essentially is a round-seg bifocal with the visible line buffed out. This blending process, however, causes some optical distortions.