Blink Reflex in Neurotrophic Keratopathy: An Electrophysiological Evaluation

PURPOSE: Neurotrophic keratitis (NK) is a rare condition which may result in visual loss. This case review investigates if there may be an association between NK and the blink reflex in the absence of facial nerve palsy and lagophthalmos. METHODS: This is a retrospective case review of 5 patients with trigeminal nerve damage referred to the oculoplastic department with suspected anesthetic corneae. Information on etiology, symptoms, duration, associated medical conditions, medications, examination findings including Mackie stage of keratopathy, management of keratopathy, and blink electrophysiology results was obtained. RESULTS: All 5 patients demonstrated absence of corneal sensation. All patients had preserved facial nerve function with no evidence of lagophthalmos. Keratopathy ranged from Mackie stage 0-2. Management ranged from ocular lubricants to Botulinum-toxin-induced ptosis. Blink studies demonstrated reduction in amplitude as well as increased latency in 2 patients, conferring reduced blink strength. Two patients demonstrated an absent blink reflex on the affected side. One patient had blink latency within the normative range; this patient recovered corneal sensation and was discharged. CONCLUSIONS: Our finding of reduced amplitude in blink studies offers both a factor in pathogenesis of NK and a potential therapeutic target. Additionally, blink studies may provide prognostic information for recovery and therefore guide management. We suggest performing blink electrophysiology in patients with trigeminal nerve damage to assess nerve function.