CCL21 and Keratoconjunctivitis sicca: When comparing the two downregulated cytokines in tear fluid with clinical dry eye tests, levels of CCL21 showed significant correlations with OSDI score (r = 0.385, p < 0.047) and ME (r = 0.488, p < 0.010), but not with other dry eye tests, smoking status, treatment with chemotherapy, nor radiation dose.