CD4 and atopic conjunctivitis: As expected, the percentage of CD4+ T cells were similar among patients with perennial allergic conjunctivitis (PAC) and healthy controls (HC) (MD 27%, IQR 24–30 versus MD 34%, IQR 28–35, resp.; P = 0.07); meanwhile, the frequency of CD25+ cells was significantly increased in patients with PAC compared to HC (MD 5%, IQR 2.9–8.2 versus MD 0.1%, IQR 0.07–1.5, resp.; P = 0.001).