Description
The cornea is the most richly innervated surface tissue in the body1 and its predominantly sensory neural supply makes it uniquely sensitive.
The ciliary branches of the ophthalmic division of the trigeminal nerve enter the cornea at mid-stromal level and divide, passing anteriorly to form a dense nerve plexus just below Bowman’s membrane. Branches also pass from here, penetrating Bowman’s membrane and terminal axons lie in a second plexus in the corneal epithelium.
Many diseases effecting the cornea tend to reduce its sensitivity.1,2 However, there are situations in which disturbance of the cornea can produce profound ocular pain. This occurs as a result of direct stimulation of the bare nerve endings lying in the epithelium.
The pain resulting from even minor epithelial lesions is usually made much worse by the abrasive and shearing effects of repeated blinking. A difficult cycle is often set-up involving lacrimation, photophobia, repeated blinking (sometimes blepharospasm) and pain. Depending on the pathogenesis, this may be unilateral and, more rarely, bilateral.
