This is a prospective cohort study to compare subjective changes in symptoms using the Ocular Surface Disease Index (OSDI) questionnaire, following the recommended dosage of the new nanoemulsion eye drops (Systane Complete)in mild to moderate dry eye patients, and to investigate objective ocular surface changes using modern clinical instruments during the study period.

This study, lasting for 3 months in total, is to investigate the changes in both subjective reports (OSDI score) and objective measurements (Non-invasive Tear Break Time (NITBUT) and other clinical signs such as corneal staining) after the use of this nanoemulsion eye drops (Systane Complete). Subjects are required to use the eyedrop qid for 3 months, and come back for follow-up at 2-week and 3-month visits. Other secondary measurements such as Meibography and lipid layer thickness, will also be investigated.

Inclusion Criteria:

1. Age 20-50 years old
2. Best corrected distance visual acuity ≥ 6/9
3. Mild to moderate OSDI score 13-32
4. Any one of the objective test positive (NITBUT/Corneal fluorescein staining/Tear osmolarity)

Exclusion Criteria:

1. Any active ocular infections
2. Inflammations or anomalies in the eyelid
3. Uncontrolled, newly diagnosed systemic diseases or with modified long-term medications within 6 months that are known to affect tear profile.
4. Pregnancy and breastfeeding
5. Contact lens wearers are required to stop contact lenses wear for at least 1 week before the evaluation.
6. Subjects who are using artificial tears or other eyedrops will be excluded.
7. Subjects who are taking systemic drugs that may cause dry eye, e.g., Antidepressants/antipsychotics, Systemic corticosteroids.