The new approach, based on nano-structure optics, replaces curved surfaces with a flat substrate etched with millions of microscopic pillars — each just one-thousandth the width of a human hair. These pillars slow light passing through them by varying amounts depending on their height and spacing, precisely controlling the direction of light waves. The result: even 1,500-degree prescriptions can be made just 2mm thick, with material utilization rates exceeding 95%.