The objective of the study is to evaluate the effectiveness of laughter therapy in relieving the symptoms of dry eye disease.

The study is designed to: Test the hypothesis that smile exercise is an effective treatment for Dry Eye Disease (DED) . Better understand the status of emotion, quality of sleep and life in DED patient by describing and evaluating a comprehensive set of features and treatment over 2 months of observation in a well-characterized group of patients.

Inclusion Criteria:

1. Sign the informed consent approved by the Ethics Committee,

2. 18 to 45 years of age,

3. Meetting the dry eye diagnostic criteria of DEWs Ⅱ and demonstrating the following 2 condition in the same eye at screening and baseline visits (Same signs must present at both in Screening visit and Baseline visit). The same signs must be present in the same eye on both visits. The following parameters:.

   • Ocular Surface Disease Index (OSDI) score: 18-80 at and baseline visit.
   • Tear film break up time (TFBUT)<8s.

4. Best corrected visual acuity ≥10/20 in each eye

5. Intraocular pressure (IOP) ≥5mmHg and≤21mmHg in each eye

6. Women of child-bearing potential must agree to use a reliable method of contraception during study participation and must demonstrate a negative urine pregnancy test at the Screening Visit.

7. Feasible for all visits and willing to follow instructions from the study investigator.

Exclusion Criteria:

1. Corneal fluorescein staining present >5 score.

2. Contact lens wearing history:

   • Used contact lenses within last 14 days prior to the Screening Visit.
   • Unwilling to avoid using contact lenses druing the study.

3. Any corneal surgery within 12 months before Screening Visit .

4. Participation in other medical studies 3 months before screening Visit.

5. Current or previous diagnosis of any following ocular conditions in 3 months:

   i). acute allergic conjunctivitis ii). infection (e.g. bacterial, viral, protozoan or fungal infection of the cornea, conjunctiva, lacrimal gland, lacrimal sac or eyelids) iii). inflammation (e.g., retinitis, macular inflammation, choroiditis, uveitis, scleritis, episcleritis, keratitis)

6. Eyelid abnormalities that affect lid function (e.g. lagophthalmos, blepharospasm, ectropion, entropion, severe trichiasis, etc.)

7. Extensive ocular surface scarring or condition that may compromise ocular surface integrity such as Stevens-Johnson syndrome, prior chemical burn, recurrent corneal erosions, persistent corneal epithelial defects, prior ocular trauma, etc.)

8. Currently diagnosis of glaucoma and under glaucoma medication or surgery treatment

9. Currently using, or intent to have any specific treatments for dry eye disease

10. Fluorescein sodium allergy

11. Pregnant, nursing, or lactating

12. Neurological or psychiatric disorders (moderate anxiety, depression and sleep disorders)

13. Uncontrolled ocular or systemic diseases

14. History of epilepsy .

15. The researchers did not consider the patient is appropriate for inclusion in this study

16. Cognitive or psychiatric defect that precludes informed consent or ability to perform requirements in the investigation.