"Pinch Test" Facilitates Donor Sensory Nerve Selection Before Corneal Neurotization for Neurotrophic Keratopathy

Neurotrophic keratopathy (NK), caused by deficient corneal innervation, leads to progressive corneal ulceration. Corneal neurotization (CN) uses nerve transfers to direct new nerve fibers to the insensate cornea to treat NK. However, selecting a donor nerve with functional nociception remains challenging, especially in pediatric patients with congenital NK. This study evaluates the "pinch test" as a reliable method to assess nociceptive function in potential donor nerves for CN.

A retrospective chart review identified patients who underwent CN at a single center between 2021 and 2023. Patient demographics, NK etiology, donor nerve selection, and postoperative sensory outcomes were analyzed. The "pinch test" was performed on the greater auricular nerve, supraorbital nerve, supratrochlear nerve, and infraorbital nerve to assess nociception based on patient response. Corneal sensation was evaluated preoperatively and postoperatively using a Cochet-Bonnet Esthesiometer (CBE) or cotton wisps.

Fifteen patients (26 eyes) underwent CN with donor nerves assessed via the pinch test. All 15 exhibited a positive nociceptive response in at least 1 tested dermatome. Mean age at neurotization was 11.9 ± 17.1 years. Among 8 patients with 12-month follow-up data, 5 patients demonstrated improved corneal sensation, with CBE measurements ranging from 10 to 45 mm in affected quadrants, 1 patient showed reflexive responses, and 2 had no sensory evidence of improvement but exhibited signs of improvement in ocular surface integrity.

The "pinch test" can assist the surgeon before sensory nerve transfer to identify dermatomes with sensory nerves as potential donors.