Neurotrophic keratitis is a degenerative corneal disease which is caused by reduced corneal innervation due to an impairment of trigeminal nerve. The most common causes of reduced corneal innervation are viral infection, such as herpes simplex and herpes zoster keratoconjunctivitis, chemical burns, physical injuries, and corneal surgery. Loss or reduction of corneal innervation (corneal anaestthesia) leads to a reduced aqueous phase of the tear film and reduced epithelial healing capacity. The progression of neurotrophic keratitis may lead to corneal ulcers, melting, and perforation. Early diagnosis and adequate treatment may prevent this catastrophic chain of events.
Intracranial space-occupying lesions such as neuroma, meningioma, and aneurysms may also determine a compression of the trigeminal nerve or ganglion and produce an impairment of corneal sensitivity which leads to neurotrophic keratitis. Systemic diseases such as diabetes, multiple sclerosis, and leprosy may decrease sensory nerve function or damage sensory fibres leading to corneal anaesthesia. The corneal epithelium is the first target of the disease showing dystrophic changes and defects with poor tendency to spontaneous healing.