Abstract: An eyeglass construction includes a hinge joint and temple bars with spreadable jaws with apertures that receive frame hinge pins. A unique key-and-lock mechanism is provided for spreading the temple jaws and holding them apart while interchangeable temple bars are removed and installed. A separate key having a lobe-shaped shank with an elliptical profile corresponds to a similar aperture through a slot in each temple bar so that when the key is turned, the jaws at the end of the temple bar are spread apart and held in a retracted state. A simple internal leaf spring molded into the temple bar bears upon a cam surface of the eyeglass frame so that a positional biasing of the temple bar is achieved.