TruFocals eyeglasses can help those of us whose eyes no longer focus easily on objects at varying distances. TruFocals glasses have a unique slider that let you focus on anything in your visual field easily. The creator of TruFocals gives a good explanation in the following video:
The essential element in TruFocals technology is the transparent distensible membrane attached to a flexible lens. When you move the slider on the bridge of the TruFocals glasses, it pushes the fluid and alters the shape of the flexible lens, changing the correction.
The result is undistorted vision over a wide field of view, which you will not get with bifocals.
Science fiction fans have been peering myopically at the interwebs for this device, having been prepared by Frank Herbert's Dune series. Consider the oil lens:
Oil lens: hufhuf oil held in static tension by an enclosing force field within a viewing tube as part of a magnifying or other light-manipulation system.
(Read more about Herbert's oil lens)
If the Kwisatz Haderach uses them, they've got to be good.
For preceding efforts in this area, focus on these links:
Seabreacher, H.G. Winter's 1939 Torpoon
'Ken lay full-length in the padded body compartment, his feet resting on the controlling bars of the directional planes, hands on the torpoon's engine levers.' - HG Winters, 1939.