The goal of this clinical trial is to investigate the efficacy and work of action of cord plasma eye drops in the treatment of neuropathic corneal pain (NCP). The main question it aims to answer if the cord plasma eye drops are effective for the treatment of NCP through its neurotrophic and anti-neuroinflammatory effects.
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;
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;
Minimal or no ocular surface fluorescein staining, with the National Eye Institute (NEI) and ocular surface Oxford score <2;
Patients who will receive cord plasma eye drops treatment
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
Active anterior or posterior blepharitis;
Presence of concomitant ocular diseases that may cause ocular pain, such as uveitis or other ocular inflammatory diseases;
Concurrent treatment with immunosuppressants, such as topical cyclosporin or steroid eye drops
Single group
Cord plasma eye drops
DrugSNEC has collaborated with Singapore Cord Blood Bank to provide cord blood plasma service, and cord blood plasma eye drops have been used as standard clinical care for patients with ocular surface diseases, severe dry eye, and NCP in SNEC.
Pain symptoms evaluated by Ocular Pain Assessment Survey (OPAS) questionnaire
Ocular pain will be assessed using the Ocular Pain Assessment Survey (OPAS) questionnaire. The Ocular Pain Assessment Survey (OPAS) is a 27-item questionnaire to evaluate the eye pain from 6 dimensions, including pain intensity for the last 24h, pain intensity for the last 2 weeks, non-eye pain intensity, quality of life, aggravating factors, associated factors and symptom relief. Each question was scored on a scale of 0-10 or 100%, with higher score representing worse pain.
Corneal nerve morphology assessment by in vivo confocal microscopy (IVCM)
IVCM (Heidelberg Retina Tomography III. Rostock Cornea Module, Heidelberg Engineering GmbH) will be used to examine the subbasal nerve plexus. The images will be analyzed using ACCMetrics software and get the quantitative nerve parameters.
Tear neuromediator levels
Tear samples will be taken from the wetted Schirmer strips, and will be subjected to neuromediators analysis using enzyme-linked immunosorbent assay (ELISA): Substance P (pg/ml; 6x dilution), CGRP (pg/ml; 4x dilution), and NGF (pg/ml; 1.5x dilution), respectively (CGRP from Phoenix Pharmaceuticals, Runcorn, UK; Substance P and NGF from R\&D Systems, Minneapolis, USA).
Ocular Surface Disease Index (OSDI) questionnaire to measure eye symptoms and the impact of quality of life.
The Ocular Surface Disease Index (OSDI), a 12-item questionnaire, will be also used to assess the symptoms of dry eye. The OSDI is a 12-item questionnaire that used to assess the eye symptoms and and their impact on vision-related quality of life.
Amount of tear production measured by Schirmer's I test
Schirmer's I test is a diagnostic method used to measure tear production by placing a standard 5 mm wide Test Strips inside the lower lid margin and assessing the amount of tear absorbed over 5 minutes.
Corneal sensitivity measurements assessed by Cochet-Bonnet esthesiometer
Corneal sensitivity measurements assess the responsiveness of the cornea to external stimuli using a contact Cochet-Bonnet esthesiometer, which employs a retractable nylon filament marked from 0 to 6 cm. The filament is progressively shortened in 0.5 cm increments until the participant perceives the stimulus. The maximum filament length that successfully triggers a response is recorded in centimeters as a measure of corneal sensitivity.
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