Diurnal Variation in Tear Osmolarity

Inclusion Criteria: 1. Healthy males and females ≥ 18 years old 2. Negative urine pregnancy results for females of childbearing potential 3. Able to read and sign an informed consent form and show willingness to comply with the study protocol visits and procedures 4. Has 20/40 BCVA or better in at least one eye 5. Does not currently wear contact lenses 6. For Aqueous-Deficiency Group: * Has symptoms of Dry Eye * Schirmer testing ≤ 10 mm * Tear Break Up Time ≤ 8 seconds * Conjunctival staining ≥ 1+ * Meibomian gland inspissations ≤ 1+ * No lid thickening, lid erythema, or thickened, turbid meibomian gland secretions 7. For Meibomian Gland Disease Group: * Has symptoms of Dry Eye * Schirmer testing ≥ 10 mm * Tear Break Up Time ≤ 8 seconds * Conjunctival staining ≥ 1+ * Meibomian gland inspissations ≥ 2+ 8. For Normal Group: * Has no symptoms of Dry Eye * Schirmer testing \> 10 mm * Tear Break Up Time \> 8 seconds * No or trace Conjunctival staining * No Meibomian gland inspissations Exclusion Criteria: 1. Any topical medication within the last three months, except for artificial tears 2. Unable to discontinue use of artificial tears during the course of the day for Visit 2 3. Any Systemic disease, which in the opinion of the Investigator, may affect ocular health or confound study results 4. Any active ocular disease other than Dry Eye Disease, Meibomian Gland Disease or Sjogren's Syndrome, which in the opinion of the Investigator, may affect ocular health or confound study results 5. Clinically significant lid or conjunctival abnormalities, neovascularization, corneal scars or corneal opacities 6. Clinically significant limbal or bulbar injection, or corneal staining not due to DES 7. Has worn hard or rigid gas permeable contact lenses within 1 year 8. Has worn soft contact lenses within 1 week 9. Has had eye surgery or an eye injury within 6 months 10. Positive urine pregnancy results for females of childbearing potential 11. Any changes in current medication within 30 days of Visit 2 or anticipated change during course of study, which in the opinion of the Investigator may confound study results