CTL in some assays have been shown to kill KC as efficiently as they kill fibroblasts [1], but the differences between the kinetics of killing becomes clear using time-lapse imaging to assay target cell death rather than the traditional end-point chromium-release assays, which may be misleading in leaking chromium through permeabilized cells significantly earlier than caspase-3 activation and morphologic changes of apoptosis. Here, CASP3 is linked to keratoconus.