Staff Sgt. Andrew P. Heath, ophthalmic technician at the 379th Expeditionary Medical Operations Squadron, replaces a lens from a pair of government-issued glasses for a patient Aug. 2, 2016, at Al Udeid Air Base, Qatar. The optometry clinic is stocked with both a lensometer, which determines the prescription of a pair of glasses, and a lens warmer, which warms a pair of frames to allow the technician to repair the frame here rather than sending it off-site. (U.S. Air Force photo/Technical Sgt. Carlos J. Treviño/Released)