The geometric mean of the tear IL-18 concentrations in the HCs with DE was 25.93 times higher (95% CI 5.62–119.76) than that of those without DE (p < 0.001) and 22.08 times higher (95% CI 8.64–56.43) than that of the pterygium groups without DE (p < 0.001). The gene discussed is IL18; the disease is pterygium.