This study is to determine the diurnal variation of tear meniscus and tear osmolarity in normal subjects and dry eye patients.

This study is to determine the diurnal variation of tear meniscus using OCT and tear osmolarity using Tearlab's osmolarity system in normal subjects and dry eye patients.

Inclusion criteria

1. Is at least 18 years old and has full legal capacity to volunteer;
2. Has read and signed the IRB Informed Consent Document;
3. Is willing and able to follow participant instructions;
4. Has clear corneas;
5. Has 20/100 uncorrected visual acuity or better;
6. Is not a hard (or rigid gas permeable) contact lens wearer within the last year;
7. Was a soft contact lens wearer, but stopped wearing at least 1 week ago;
8. Has dry eye according to the study definition of DES (study subjects).

Exclusion criteria

1. Has any systemic disease affecting ocular health except for Sjögren's syndrome;
2. Is using any systemic or topical medications that will affect ocular health except for artificial tears;
3. Has an active ocular disease other than DES, meibomian gland disease or Sjögren's syndrome
4. Has any clinically significant lid or conjunctival abnormalities, neovascularization, corneal scars or corneal opacities;
5. Has limbal or bulbar injection or corneal staining that was clinically significant, which are not due to DES;
6. Has worn rigid gas permeable lenses within 1 year;
7. Has had surgery or an eye injury within 6 months.

Normal subjects vs. dry eye patients