In a study in diabetic patients with and without dry eye, and non-diabetic patients with dry eye, Zhang et al. reported significant increase in levels of IL-1β and TNF-α in biopsy samples collected from diabetic dry eye group and determined that the IL-1β and TNF-α positive cells were mainly localized in the basal layer indicating that inflammatory response may not be limited to the surface, but could be more serious in deeper layers of conjunctival epithelium (150). Here, TNF is linked to dry eye syndrome.