Evaluation of the Clinical Efficacy and Mechanisms of Cord Plasma Eye Drops in the Treatment of Neuropathic Corneal Pain

Inclusion Criteria: 1. Persistent ocular pain or pain-like symptoms, including burning sensation, allodynia, photoallodynia, stinging, hyperalgesia, throbbing, shooting, sharp, cramping, gnawing, or a feeling of electric shock, with a minimum score of 30% for more than 3 questions in the OPAS questionnaire (see below section for OPAS questionnaire), for at least 3 months; 2. Presence of corneal nerve abnormalities, including microneuromas, beading, nerve tortuosity, decreased in corneal nerve fiber density (CNFD) or corneal nerve fiber length (CNFL), on IVCM images; 3. Minimal or no ocular surface fluorescein staining, with the National Eye Institute (NEI) and ocular surface Oxford score \<2; 4. Patients who will receive cord plasma eye drops treatment Exclusion Criteria: 1. Presence of active ocular surface diseases, such as active infective keratitis, the presence of epithelial defect or any other conditions that may cause nociceptive pain 2. Active anterior or posterior blepharitis; 3. Presence of concomitant ocular diseases that may cause ocular pain, such as uveitis or other ocular inflammatory diseases; 4. Concurrent treatment with immunosuppressants, such as topical cyclosporin or steroid eye drops 5. Concurrent use of oral Nonsteroidal anti-inflammatory drugs (NSAID) or other medications that may affect the pain scores