TRPA1 was reported to be activated by noxious cold (< 17°C) in human KCs in vitro (Nagata et al., 2005; Tsutsumi et al., 2010), whereas global trpa1-knockout mice and rats exhibited normal cold sensations (Bautista et al., 2006; Reese et al., 2020). This evidence concerns the gene TRPA1 and dry eye syndrome.