The Eyejusters aren't the world's first adjustable eyeglasses that can be tweaked without the need for an optometrist. But they take a new approach to the idea that seems to offer some distinct advantages.
Previous efforts have used flexible liquid-filled lenses that become thinner or thicker as liquids are pumped in and out. But the Eyejusters instead use a pair of specially-shaped sandwiched lenses that are able to slide across each other. And as the positions of the lenses change by turning a removable adjustment tool, so does their focal range.