Inclusion Criteria:  Subjects with stage 2 (PED) or stage 3 (corneal ulcer) NK. Subjects with bilateral NK may enroll in the study but only one eye will be selected as the study eye (worse eye) and be treated with test article. The non-study eye may not be treated with Oxervate concurrently. Subjects with no clinical evidence of improvement in the PED or corneal ulcer within the 2 weeks prior to study enrollment despite the use of conventional non-surgical treatments for neurotrophic keratitis (e.g., preservative-free artificial tears, gels or ointments; discontinuation of preserved topical drops and medications that can decrease corneal sensitivity; therapeutic contact lenses [either silicone hydrogel or rigid gas permeable]) as determined by the investigator or referring physician's medical record. Subjects with clinical evidence of decreased corneal sensitivity within the area of the PED or corneal ulcer and outside of the area of the defect in at least one corneal quadrant in the study eye in the opinion of the investigator (assessed with a cotton wisp, or the Cochet-Bonnet aesthesiometer if available at the site). Best-corrected distance visual acuity (BCDVA) score ≤ 75 ETDRS letters measured with a LogMAR chart (≥ 0.2 LogMAR, ≤ 20/32 Snellen or ≤ 0.625 decimal fraction) in the affected eye. Subjects must have the ability and willingness to comply with study procedures.  Exclusion Criteria:  Any active ocular infection (bacterial, viral, fungal, or protozoal) or active ocular inflammation not related to NK in either eye in the opinion of the investigator. Infectious epithelial keratitis including herpetic keratitis (i.e., dendritic lesions or geographic ulcers) in either eye is excluded. Subjects on oral antibiotic at the time of screening are eligible but should continue the medication for the duration of the study. Previous use of Oxervate in the study eye within the past 4 months. Any other ocular disease that will require topical ocular treatment in the study eye over the course of the study. Monocular subject (subjects with one functioning eye defined as having any ocular pathology that results in a pinhole distance visual acuity 20/100 or worse [Snellen]). Use of any other topical treatments other than the study medications provided by the Sponsor and allowed by the study protocol can be administered to the study eye over the course of the study. Subjects will be required to instill once-daily prophylactic preservative-free antibiotic eye drops starting on Day 0 until the defect is healed.  Note: Other inclusion/exclusion criteria apply.