Imagine eyeglasses that worked a lot like your own eyes, capable of focusing on whatever you're looking at automatically. For those who constantly need to swap out reading glasses, such an invention would be a huge step up in convenience.

Well, the future may be here on that front. A team of researchers at the University of Utah have developed a set of "smart glasses" that adjust focus depending on whether the object being viewed is nearby or far away. In fact, the glasses can change focus from one object to another in just 14 milliseconds, so wearers will hardly be bothered by the adjustment, reports Phys.org.

"Most people who get reading glasses have to put them on and take them off all the time," said Carlos Mastrangelo, team leader. "You don't have to do that anymore. You put these on, and it's always clear."

The research was published this week in a special edition of the journal Optics Express.

The secret ingredient is glycerin

The eyeglass lenses are made of glycerin, a thick colorless liquid, and are enclosed by flexible rubber-like membranes in the front and back. The membranes adjust thanks to built-in mechanical actuators that push them back and forth like a transparent piston, which changes the curvature of the liquid inside. That's how the glasses can change focus without having to swap out any lenses.

A rechargeable battery to power the actuators can be found in the eyeglass frames. Meanwhile, the bridge of the frames contains a distance meter that constantly fires out pulses of infrared light, which is how the glasses can judge the distance to an object and adjust the focus automatically. All of those electronics in the frames contribute to a rather bulky look, but researchers aren't prioritizing fashion just yet. Even so, a lighter, more stylish version is already in development.

Researchers also designed a companion smartphone app for the glasses that allows users to input their eyeglasses prescription, so it's easy to get them calibrated for anyone's eyes. Obviously, since the glasses can automatically adjust focus and be easily calibrated, they're the last pair you may ever have to own.

If all goes according to plan, the technology should be available to consumers in as early as three years.