Oculofacial Pain: Corneal Nerve Damage Leading to Pain Beyond the Eye.

The cornea is supplied principally by the ophthalmic branch of the trigeminal nerve and is the most densely innervated organ in the human body. Under normal conditions, the corneal nerve terminals incorporate sensors that monitor the thickness and integrity of the tear film, which are essential for meaningful vision. A disrupted tear film or direct noxious stimulation of these corneal nerves can produce discomfort or pain limited to the affected surface. Damage to these nerves can sometimes lead to a chronic neuropathic condition, where pain persists months following the initial insult, long after the nerves appear to have healed in the cornea itself following treatment. Neuropathic pain appears to persist indefinitely in a few patients.