“…1 There is agreement that CXL is a safe and effective treatment 1,2 ; however, its exact mechanisms of action are not completely understood. There is only indirect evidence for the presence of crosslinks in the cornea after CXL, such as increased stress-strain values, 3,4 increased resistance to collagenases in vitro, 5 increased shrinking temperature, and increased collagen fiber diameter. 6,7 Given the clinical success of CXL, it is frustrating that we do not have a reliable tool to assess the crosslinking effect directly or indirectly after treatment in the individual case.…”