Lenses mounted in rimless style frames, including nylon cord and full metal or plastic that surround the frame, are prone to chipping.
New styles are smaller, stiffer and designed with sharp corners. All of these issues cause more stress on the lens.
Save yourself the hassle and embarrassment of a patient returning a frame with chipped and broken lenses. The material selected for ALL RIMLESS should be POLYCARBONATE or TRIVEX MATERIAL.