Josh Silver makes affordable, adjustable eyeglasses with a dream to solve the vision problems of the world. He begins by asking the audience to raise their hands if they wear glasses or contact lenses, or if they’ve had laser refractive surgery. “It’s too many of you to count,” he says, “but the general statistic is about half.” He asks us to project that statistic to the world. And as we do so, he asks that we remember that poor vision is not just a health problem, but educational and economic as well. If you’re a child in developing world with poor eyesight and no access to vision correction, you miss out on education.

According to Silver, the real problem is that there aren’t enough eyecare professionals in the world to use the developing world’s model of delivery everywhere in the world. He points out that some countries in sub-Saharan Africa have only one optometrist for every eight million people. So, he came up with a solution based on adaptive optics (which also helped Andrea Ghez see the stars).

Running out of time, Silver gives a demo of his glasses with his adjustable lenses. He quickly puts them on and adjusts the lenses’ strength by injecting liquid into the them through two ingeniously compact attachments. He declares “I can now see that guy running around in the back. And now that one.”

These aren’t the only glasses like this in the world, he explains. Silver has put about 30,000 in use now. He delivers his global vision for vision: To get one billion people wearing the glasses they need by 2020. Currently a pair costs $19, and the distribution hurdle will only be crossed when the cost is brought down to serve populations that live on less than one dollar per day.