DQS is a purinergic P2Y2 receptor agonist, which may stimulate the secretion of water and mucin from conjunctival epithelial cells and goblet cells.[16,17] Previous studies reported that DQS could effectively relieved various symptoms of dry eye and improve the visual function of the dry eye patients.[17–19]. This evidence concerns the gene MUC5AC and Keratoconjunctivitis sicca.