The high-tech, electro-active eyeglasses would not be heavy, geeky or require donning a bulky battery pack.

And they might just revolutionize vision correction for presbyopia, an age-related condition that makes close objects blurry for many people who are middle-aged and older.

So says optometrist Ron Blum -- chairman, president and chief executive officer of Roanoke-based PixelOptics.

Blum avoids describing specifics about how the lenses work. But here are details he shared:

Buried inside a refractive lens, which bends light as traditional eyeglass lenses do, is a thin layer of liquid crystal.

A sensor communicates with a microprocessor to automatically adjust focus depending on where a user looks.

A controller changes the refractive index of the liquid crystal in the lens, providing a focus that is appropriate for objects near or far.

Vivien Casagrande is a professor of cell and developmental biology, psychology, ophthalmology and visual sciences at Vanderbilt University Medical Center.

Casagrande reviewed Blum's general description of how the electro-active eyeglasses could work as a treatment for presbyopia.

In an e-mail, she emphasized she would need more detailed information for a complete evaluation and that she fully supports innovation.

"Sounds like a good solution for presbyopia, but only for presbyopia," Casagrande said. "To keep close-by objects in focus, the focus need not be corrected very frequently or very quickly, so the millisecond response seems reasonable."

Casagrande posed a few questions.

Will the focus change quickly enough when switching from near objects to far? How might the lenses improve upon bifocals or progressive addition lenses? For distant objects, how far is the lens' range? While driving, "if focus must shift from the traffic lights to the dashboard, will this work?"

Also, if head movements trigger the sensing mechanism, relying on movements of the head would not work well because "one may need to look ahead but glance down without moving the head," she said.

Blum responded.

He said the focus will change faster than the eye can blink. He said the electro-active lenses promise far less "unwanted astigmatism" and distortion than conventional eyeglasses correcting for presbyopia.

He said the PixelOptics lenses, unlike conventional lenses, will allow wearers to see clearly their feet and stairs, as well as participate in sports while wearing the glasses. Distance vision will be the same as conventional eyeglasses.

The microprocessor, microsensor and a miniature rechargeable battery all will be housed within the eyeglasses. Blum said the glasses will be "thin, lightweight and very fashionable."

Frames will come in various styles, he said, including plastic, wire, metal, rimless and semirimless.

He said PixelOptics has protected the lens technology with 20 U.S. patents, 18 foreign patents and more than 150 patent applications pending.

Blum would not say what the fancy glasses might sell for at retail but insisted the price will be affordable.

"We've really done our homework. I think people are going to be really surprised by the selling price and the aesthetics," he said.

Presbyopia is a condition caused by aging of the lens in the eye and the muscles that control its shape. The lens becomes more rigid and does not flex as easily.

Blum said research shows that 95 percent of people 40 and older develop presbyopia and that about 1.6 billion people worldwide are presbyopic.

So, he said, the market for PixelOptics' product is promising.

PixelOptics is working to develop a separate but related product that might have military applications.

The company says its "SuperVision" technology, which differs slightly from the electro-active lenses', could enable military personnel to have better than 20/20 vision.

In a 2006 news release, Blum observed, "SuperVision is intended to provide the U.S. military forces with a competitive combat advantage and reduce the number of friendly fire incidents."

On the Net: www.pixeloptics.com.