SURF-200 is being studied in people experiencing an episodic flare-up of their dry eye disease. SURF-200 is an investigational drug (which means the study drug is currently being tested) in the form of a sterile eye drop.

The purpose of this research study is to see how well SURF-200 works and what side effects there are, and to compare it with vehicle (placebo). The study will involve about 120 study participants at multiple research sites in the United States.

Inclusion Criteria:

1. Subjects 18 years of age and older who have a diagnosis of dry eye disease and experiencing an episodic flare up. Criteria for the diagnosis must include the following:

   1. UNC DEMS score of greater than or equal to 5 but less than or equal to 9
   2. Conjunctival hyperemia score of greater than or equal to 2 in the study eye when using the conjunctival hyperemia reference photos
   3. Schirmer's Tear Test score (with anesthesia) greater than 1 mm but less than or equal to12 mm in the study eye

2. Subjects must be able to understand and sign the Informed Consent Form (ICF).

3. Female subjects of childbearing potential must agree to and submit a negative urine pregnancy test before any study-specific procedures are performed. The subjects must be using and continue to use a suitable method of contraception for the duration of the study: spermicide with barrier, oral contraceptive, transdermal contraceptive, injectable or implantable contraceptive, intrauterine device (IUD), abstinence or surgical sterilization of a partner. If a subject is not of childbearing potential (e.g., has been postmenopausal for at least 12 months or is premenarchal, or has undergone a hysterectomy, bilateral oophorectomy or a bilateral tubal ligation), a urine pregnancy test and use of a suitable method of contraception for the duration of the study will not be required.

4. Subjects must have a best-corrected visual acuity (BCVA) of at least +1.0 log of the minimum angle of resolution (logMAR) (Snellen equivalent of 20/200) in the non-study eye (fellow eye).

5. Subjects must have an intraocular pressure (IOP) of >8 mmHg and ≤22 mmHg in the study eye.

6. Subjects who are on Restasis, Xiidra or other cyclosporine ophthalmic eye drops must be on a stable dose for at least 4 months prior to Screening Visit 1 (Day -14 to Day 0) and remain compliant with the use of these medications throughout the duration of this study.

7. Subjects who are on artificial tears, oral antihistamines, beta blockers and diuretics must be on a stable dose for at least 1 month prior to Screening Visit 1 (Day -14 to Day 0) and remain compliant with the use of these medications throughout the duration of this study.

8. Subjects must be willing and able to attend all study visits and follow all instructions.

9. Subjects must be able to self-instill the study drug (if unable, a caregiver must be available to instill all doses of the study drug).

10. Have a history of use or desire to use an eye drop for dry eye symptoms for longer than the past 6 months.

Exclusion Criteria:

1. Females who are pregnant or nursing or planning to become pregnant during the study. Females of childbearing potential (not surgically sterilized or postmenopausal) may not participate in the study if they do not agree to use adequate birth control methods for the duration of the study.
2. Use of contact lenses in either eye during the study. Contact lens wear must have been discontinued at least 2 weeks prior to Baseline/Randomization Visit 2 (Day 1).
3. Use of corticosteroids or nonsteroidal anti-inflammatory agents (NSAID) (except oral doses of aspirin at 81 mg/day or lower) within 2 weeks of the initiation of study drug at Baseline/Randomization Visit 2 (Day 1) and for the remainder of the study.
4. Inhaled, ingested, sublingual, transdermal or topical products containing marijuana, tetrahydrocannabinol (THC) or cannabidiol (CBD) within 7 days of the first dose of study drug at Baseline/Randomization Visit 2 (Day 1) and for the remainder of the study.
5. Presence or history of treatment with systemic immunosuppressive or chemotherapeutic agents.
6. History of high IOP response to steroids.
7. Participated in an ophthalmic investigational product clinical trial within 30 days of Screening Visit 1 (Day -14 to Day 0).
8. Active collagen vascular disorder or autoimmune disease.
9. A condition or a situation, which in the investigator's opinion may put the subject at increased risk, confound study data, or interfere significantly with the subject's study participation.
10. Known hypersensitivity to any component of the study drug or procedural medications.
11. Known hypersensitivity to steroids.
12. Any active corneal epithelial/stromal pathology noted in the study eye at Screening Visit 1 (Day -14 to Day 0).
13. Any history of corneal surgery in the study eye (including corneal crosslinking, radial keratotomy, corneal transplant, or LASIK).
14. Any ocular surgery in the study eye within the past year.
15. Subject has punctal occlusion with any modality or a change in punctal plug status in either eye within the 3 months prior to Screening Visit 1 (Day -14 to Day 0).
16. Subject has a history of glaucoma.
17. Subject has a history of herpes simplex infection in either eye.
18. Subject has active corneal, conjunctival or canalicular pathology (including ocular infection [bacterial, viral or fungal]) in either eye. Specifically, active viral diseases of the cornea and conjunctiva including epithelial herpes simplex keratitis (dendritic keratitis), vaccinia, and varicella, and mycobacterial infection of either eye and fungal diseases of the ocular structures (such as fungal keratitis).
19. Subject has thinning of the cornea or sclera in the study eye.
20. Subject has active anterior blepharitis in the study eye.
21. Subject has a history of uveitis in the study eye.
22. Subject is suffering from alcohol and/or drug abuse.
23. Subject has tested positive for the COVID-19 virus within 30 days prior to Screening Visit 1 (Day -14 to Day 0).
24. Subject has previously received treatment in this study protocol.
25. Subject is taking a medication, that in the opinion of the investigator, might interfere with the study parameters.