Differences in Corneal Structure and Function in Patients With Sjogrens vs. Non-Sjogrens Dry Eye

In this study the investigators plan to enroll three groups of patients: non-Sjogren's dry eye, Sjogren's dry eye and controls. The study has the following primary goals: 1. To determine whether dry eye is associated with reduced corneal sensation 2. To determine whether reduced corneal sensation is due to the severity of the dry eye, the type of dry eye (primarily aqueous deficient versus primarily evaporative) or entirely related to the presence of Sjogren's 3. To determine whether corneal sensation is associated with ocular or systemic pain symptoms Additionally, the study aims to compare the novel corneal esthesiometer measurements to confocal biomicroscopy findings in determining neurotrophic keratitis (NK) and assess correlations between corneal sensation.