Examining tears from patients with KC or those who underwent CXL treatment, Balasubramanian et al. have found significant elevations in many cytokines (IL-4, IL-5, IL-6, IL-8, TNF-α, and TNF-β) in tears from KC patients and only significant elevation of TNF-α in the CXL treated group compared with controls [169]. Here, TNF is linked to keratoconus.