The objective is to compare the USL and placebo in terms of efficacy and safety, and to determine the appropriate dosage.

This study is a phase 2, dose-finding, double-blind, randomized placebo-controlled trial of two different doses of USL compared with placebo. A total of 120 patients, aged over 19 years, with Corneal staining score(Oxford grading) ≥ 2 or TBUT < 10 sec and OSDI ≥ 10 points will be recruited at Daejeon University Daejeon Korean Medicine Hospital. Patients will take medications two times daily for 12 weeks, with 5 visiting days(screening, week 0, week 6, week 12, week 14).

Inclusion Criteria:

• Aged over 19
• Screening both eyes, the corrected visual acuity is 0.2 or more
• Subjects with Fluorescein Corneal Staining score (Oxford grading) ≥ 2 or TBUT test ≤10 at screening
• Subjects with OSDI ≥ 13
• Subjects who voluntarily agreed to participate in this clinical study in written form

Exclusion Criteria:

• Current or history of ocular disorders possibly affecting the study results (ocular surgery, trauma, diseases) as followings within 2 months:

  1. Abnormal eyelid function: disorders of the eyelids or eyelashes
  2. Ocular allergies or currently under the treatment of allergic diseases of the eye (topical ocular mast cell stabilizer, antihistamine use, etc.)
  3. Cicatricial keratoconjunctivitis caused by herpetic keratopathy, conjunctival scarring (alkali damage, Steven-Johnson syndrome, cicatricial pemphigoid), pterygium, pinguecula, lack of congenital lacrimal, neurogenic keratitis, keratoconus, corneal transplantation

• Those with acute eye inflammation/infection within 1 month

• Those who have undergone eye surgery (including LASIK/LASIK) within 3 months

• Those who had taken lacrimal punctal occlusion, cauterization of the punctum, or intense pulsed light procedure within 3 months

• Those who wear contact lenses within 72 hours of screening or plan to wear contact lens during the study period

• Intraocular pressure (IOP)> 25 mmHg in more than one side

• Autoimmune disease (e.g., Sjogren's syndrome, Rheumatoid arthritis, systemic lupus erythematosus, Graves' disease)

• Those who have used cyclosporine or diquafosol use in any form (systemic, topical) within 1 month

• Medical condition or history within 1 month to be treated with topical agents besides artificial tears (glaucoma, ocular allergy, ocular inflammation/infectious disease, etc.)

• Those who have taken or are taking steroid drugs or immunosuppressants (Azathioprine, Tacrolimus, Cyclosporin, Mycophenolate mofetil etc.) that may affect immune function within 3 months prior to screening

• Those who had taken antihypertensive drugs such as antihistamine and beta blockers, diuretics, antidepressants (especially tricyclic antidepressants, Parkinson's treatment drugs, etc.) that can worsen dry eye cannot participate in this study

• Severe abnormal liver function tests (Alanine transaminase (ALT) or Aspartate transaminase (AST) values ≥ 2 times the upper limit of normal) and abnormal renal function (Creatinine values ≥ 2 times the upper limit of normal)

• Genetic disorders, such as galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption

• Comorbidities that may interrupt the treatment of cancers or clinically significant disorders of the kidney, liver, psychiatric system, cardiovascular system, respiratory system, endocrine system, and central nervous system, the safety assessment, or completion of this clinical study

• Unregulated hypertension (high blood pressure of 160 mmHg in the condenser or high blood pressure exceeding 100 mmHg in the relaxation period)

• Unregulated diabetes (fasting blood sugar (FBS) exceeding 180 mg/dL)

• Hepatitis A (active) or hepatitis B (active) or hepatitis C

• History of hypersensitivity reaction to active ingredients or excipients of the investigational product

• History of excessive alcohol use or drug addiction

• Pregnant or lactating women

• Those who did not agree to use contraception by medically permitted methods (e.g., surgical treatment of infertility, intrauterine device, condom or diaphragm, and injectable or insertable contraceptives) during the period from dosing of the investigational product to 90 days after the clinical study, among female subjects of childbearing potential and male subjects with the female partner

• Those who had experience of participating in a different clinical study within 4 weeks prior to participation in this clinical study

• Subjects who were determined to be ineligible to participate in this study