Observe the changes of tear volume in dry eye patients after Restasis treatment of 3 months and during 6-month follow-up after discontinuation of study treatment.

Using an imaging device name optical coherence tomography to image the tear volume in dry eye patients before and after Restasis treatment.

Inclusion Criteria:

The participant will be eligible for entry in the study if s/he:

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. Has dry eye according to the study definition of DES (study subjects);
7. Has not use Restasis within 3 months.

Exclusion Criteria:

The subjects will ineligible for entry into the study if s/he:

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, 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 and during the study;
7. Has had surgery or an eye injury within 6 months;
8. Was a soft contact lens wearer within 2 weeks and during the study.

dry eye patients more than 18 yrs old