Human Umbilical Cord Mesenchymal Stem Cell-derived Small Extracellular Vesicles for the Treatment of Dry Eye Disease

Inclusion Criteria: * Subjects who voluntarily participate and sign the informed consent form, are willing to comply with the treatment schedule specified in the study protocol, and attend follow-up visits on time. * Aged ≥ 18 years, with no gender restriction. * Best-corrected visual acuity (BCVA) of both eyes (OU) ≥ 0.1 at the Screening Visit (Visit 1, V1). * History of dry eye disease in both eyes prior to the Screening Visit (Visit 1, V1), with at least one of the following subjective symptoms: ocular dryness, foreign body sensation, burning sensation, eye fatigue, discomfort, redness, or fluctuating visual acuity. * Meeting one of the following criteria at the Screening Visit (Visit 1, V1): i. Positive corneal fluorescein staining, TBUT \< 10 s, and OSDI score ≥ 13; ii. Negative corneal fluorescein staining, TBUT \< 5 s, and OSDI score ≥ 13 Exclusion Criteria: * Subjects with current ocular herpes or any other ocular infection or inflammation, or a history of ocular herpes or any other ocular infection within 30 days prior to screening. * Subjects with ocular diseases including structural abnormalities of the eyelid margin (ectropion, entropion, eyelid laxity, etc.), severe conjunctivochalasis, Salzmann nodular corneal degeneration, damaged conjunctival goblet cells (e.g., vitamin A deficiency), progressive pterygium, wet age-related macular degeneration (wAMD), glaucoma, diabetic retinopathy, retinal vein occlusion, etc., which, in the investigator's opinion, may increase subject risk or interfere with study outcomes. * Subjects with secondary ocular scarring that, in the investigator's assessment, may affect subject compliance or outcome evaluation (e.g., radiation scars, chemical burns, Stevens-Johnson syndrome, cicatricial pemphigoid, etc.). * Subjects with secondary Sjögren's syndrome or other autoimmune diseases (e.g., rheumatoid arthritis, systemic lupus erythematosus, etc.), unless the subject meets all of the following conditions: 1. Not receiving steroids, immunomodulatory, or immunosuppressive agents for the disease; 2. The investigator determines that the medical condition will not impact study results. * Subjects with a history of organ or bone marrow transplantation. * Subjects who wore contact lenses within 30 days prior to screening. * Subjects who received physical therapy for dry eye within 30 days prior to screening, including eyelid scrubbing, meibomian gland expression, warm compresses, fuming, or IPL laser therapy for bilateral dry eye. * Subjects who received oral aspirin or aspirin-containing medications, or used NSAIDs (topical ocular or systemic), or drugs known to induce ocular dryness (e.g., anticholinergics, SSRIs, etc.) within 30 days before dosing, unless the subject has been on a stable dose of such medication for at least 30 days before the baseline visit, with no expected changes during the study. * Subjects who used the following medications within the specified periods before dosing: 1. Antihistamines (ocular or systemic) or any topical ophthalmic medications within 14 days before dosing; 2. Artificial tears within 14 days before dosing; 3. Steroids or mast cell stabilizers (ocular or systemic) within 30 days before dosing; 4. Varenicline or diquafosol within 30 days before dosing; 5. Topical ocular cyclosporine or tacrolimus within 6 weeks before dosing. * Subjects with punctal plugs implantation or a history of punctal cautery within 12 weeks prior to screening. * Subjects who used antiglaucoma medications within 3 months prior to screening, had non-laser glaucoma surgery, or underwent glaucoma laser surgery within 6 months prior to the screening visit. * Subjects who underwent Nd:YAG laser capsulotomy within 6 months prior to screening, or corneal refractive surgery (e.g., LASIK) within 12 months prior to screening. * Subjects with known allergy to fluorescein, multiple drug allergies, or severe allergic diseases. * Subjects with other poorly controlled clinical conditions, such as severe chronic infection, severe cardiopulmonary disease, uncontrolled hypertension (defined as systolic blood pressure ≥ 150 mmHg or diastolic blood pressure ≥ 100 mmHg despite antihypertensive treatment), uncontrolled diabetes mellitus, malignant tumors, etc. * Female subjects with a positive pregnancy test or lactating subjects; female subjects of childbearing potential or male subjects whose partners are of childbearing potential who are unwilling to use contraception during the study and for 1 month after the last dose of study medication. * Subjects who participated in any other clinical trial of investigational drugs or devices within 30 days prior to screening. * Any other conditions deemed by the investigator to make the subject ineligible for enrollment (e.g., depression, etc.).