LOS ANGELES — As a promising Caltech graduate student in applied physics, Stephen Kurtin could have taken a job offer from Intel at the dawn of the microelectronics era 40 years ago. Instead he followed the path of a lone inventor, gaining more than 30 patents in fields including word processing software and sound systems, culminating in the pair of glasses resting on his nose, which he believes can free nearly two billion people around the world from bifocals, trifocals and progressive lenses. The glasses have a tiny adjustable slider on the bridge of the frame that makes it possible...