A PHASE II PROSPECTIVE RANDOMIZED DOUBLE-MASKED CROSSOVER STUDY ASSESSING THE SAFETY & EFFICACY OF RHPRG4 (450 μG/ML RECOMBINANT HUMAN PROTEOGLYCAN 4) COMPARED TO VEHICLE FOR THE TREATMENT OF OCULAR GRAFT-VERSUS-HOST DISEASE (OGVHD)

Inclusion Criteria:

1. Have the ability to comprehend and provide a signed and dated consent form.

2. Are 18-80 years of age at time of consent;

3. Have been diagnosed with oGVHD for at least 3 months prior to giving informedconsent to participate in the trial;

4. Current use of artificial tears for the treatment of oGVHD related dry eye;

5. Have been stably using systemic medications for at least 14 days prior to Visit 1;

6. VAS Eye Dryness (100-point scale) score ≥ 40 mm;

7. Average VAS score for all symptoms of dry eye (dryness, foreign body sensation,burning/stinging, itching, pain, stick feeling, blurred vision and photophobia) ≥ 25mm, none < 5 mm;

8. Have Oxford corneal fluorescein staining grade of ≥ 2 using the Oxford scale in theworst performing eye

9. Stated willingness to comply with all study procedures, attend all scheduled clinicvisits, and continue participation for the duration of the study;

10. Ability to self-administer study medication and willingness to adhere to themedication regimen.

Exclusion Criteria:

Are currently or have a history of any ocular or systemic disorder or condition other than dry eye that based on investigator judgment will interfere with the interpretation of the study results. Examples of ocular or systemic disorders or conditions include active ocular infection, conjunctivochalasis, superior limbic keratoconjunctivitis, limbal stem cell deficiency, allergic conjunctivitis, giant papillary conjunctivitis, atopic keratoconjunctivitis, anterior basement membrane dystrophies, neurotrophic keratitis, corneal dystrophy, exposure keratitis, moderate to severe blepharitis, ocular trauma, progressive or degenerative corneal conditions, uveitis, and systemic infection; 2. History of any ocular surgery (including laser or refractive surgical procedures) or therapeutic medical devices in either eye within 30 days before study enrollment. Therapeutic medical devices include trigeminal stimulation, meibomian glad warming (excepting at home masks) or expression, intense pulsed light, low level light therapy, etc. Ocular surgeries include laser or refractive surgical procedures, insertion of punctal or punctal cauterization; Ocular surgery will not be allowed during study participation; 3. Initiation of new therapeutic modalities within 14 days of Visit 1; 4. Have a known hypersensitivity to one of the components of the study or procedural medications; 5. Have participated in another clinical study at the same time as the present study or within 30 days of the Visit 1; 6. Have a history of drug, medication or alcohol abuse or addiction; 7. Are females of childbearing potential (those who are not surgically sterilized or post-menopausal for at least 1 year) who meet any one of the following conditions:

1. are currently pregnant or,

2. have a positive result on the urine pregnancy test at the Screening/Baseline Visitor,

3. intend to become pregnant during the entire course of and 30 days after the studytreatment periods, or,

4. are breast-feeding or,

5. not willing to use highly effective birth control measures, such as: hormonalcontraceptives - oral, implanted, transdermal, or injected and/or mechanical barriermethods, during the entire course of and 30 days after the study treatment periods;

6. Per the discretion of the investigator or designee, history of a serious physicalor mental disorder that prevents the subject from attending study visits, complyingwith study-related procedures, and/or prevents the subject's ability to makedecisions on their own; 9. Any other surgical or medical condition or finding thatin the opinion of the investigator would compromise the subject's safety orparticipation in the study.