In a systematic review and meta-analysis of case-control and cross-sectional studies with 374 patients (374 eyes) with keratoconus showed tear levels of IL-1β, IL-6, and TNF-α significantly increased in keratoconus compared with normal controls, with standardized mean differences of 1.93 (95% CI 0.22 to 3.65, p = 0.03) for IL-1β, 1.22 (95% CI 0.59 to 1.84, p < 0.001) for IL-6, and 1.75 (95% CI 0.66 to 2.83, p = 0.002) for TNF-α [42]. Here, IL6 is linked to keratoconus.