For people who just can't adjust to wearing regular bifocals or progressive lenses, help is here. Adjustable-focus glasses have a nosepiece slider that let the user adjust the focus for distance, intermediate or near vision. Optometrists say the glasses work well but they are far from fashionable.
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Presbyopia, which typically starts in the early-to-mid 40s, is an aging of the eye's lens that results in an inability to focus on nearby objects. Symptoms are blurred vision, a tendency to hold reading material at arm's length and headaches when doing close work.
Options for treating it include reading glasses, bifocals and progressive lenses, which provide a 
progression of lens powers without a visible line. Lenses that combine reading and distance prescriptions often require users to point or tilt their head for optimal vision, optometrists say. Many people are happy with bifocals and progressives, but others never adjust to having to look through a narrow area of the lens for optimal vision.
A new type of eyeglass called TruFocals, sold by Zoom Focus Eyewear LLC of Van Nuys, Calif., allows users to manually focus the entire lens. The glasses contain two lenses—a normal distance prescription on the outside and behind it, a flexible plastic lens filled with a clear optical fluid. As the user moves the slider the pressure on the fluid changes, altering its shape. When the slider is at the far left, reading magnification is off and distance vision is optimized. As it is moved to the right, reading magnification increases.
TruFocals cost $895 on the Web with a 30-day free trial, and are also available from a small number of optometrists. So far, there are no published clinical trials on the glasses. Optometrists who have seen them give them high reviews on function, but they also say many clients won't like the Harry Potter-like frames, the design of which Zoom Focus says is needed for optimum vision quality. "If you are looking strictly for functionality, it is a great solution," says Chris Stanwick, a Belpre, Ohio, optometrist who sold two pairs.
The adjustability is particularly useful for computer work—where bifocals and progressives tend to force users to tilt their head to get into the sweet spot of the lens, says Boston-area optometrist David S. Greenstein, who bought a pair for himself that he is showing to customers. TruFocals also solve the annoying problem of being forced to use the reading portion every time you look down. For this reason, walking down stairs or stepping off curbs can be troublesome with bifocals and progressives, Dr. Stanwick says. And golfers who want to see the ball clearly while looking down but need readers to see their score card can also benefit, optometrists say.
People who may find them useful are diabetics, whose vision can change slightly daily, and mechanics or electricians, who need magnification when looking up. NASA is evaluating them for use in space flights since astronauts must be able to focus while looking in any direction. "The optics are crystal clear," says C. Robert Gibson, a senior optometrist at the Johnson Space Center in Houston.
I tested the glasses at Dr. Greenstein's office while wearing contact lenses, but without a distance lens. The glasses were easy to use to read small print on an aspirin bottle, but adjusting them called for two hands—one to adjust the slider and one to hold on to the glasses. Zoom Focus says experienced users can do it one-handed and that the focusing becomes automatic with time.
The fashion-conscious might want to wait for PixelOptics Inc.'s new electronic glasses, which will be available nationally in early 2011, with a choice of more than 20 frames. The glasses, expected to cost about $1,000 to $1,200, will be like regular progressives but with a switch on the side of the frame that lets users turn off the reading lens to gain a larger intermediate-vision zone, the Roanoke, Va., company says.
The downside: They contain a small battery that must be charged by placing the glasses on a charging tray every two or three days.
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