Corneal Innervation and Sensation: The Eye and Beyond

Abstract

The cornea is one of the most densely innervated and sensitive tissues in the body. In addition to their important sensory functions, corneal nerves induce reflex tear production, blinking, and the release of trophic factors - all of which combined help to maintain the structural and functional integrity of the surface of the eye. Consequently, damage to corneal nerves as a result of disease, surgery, or trauma can lead to diminished corneal sensitivity, epithelial defects, and possible blindness. In this review, we describe commonly used tools that have provided considerable new information on corneal architecture and sensation in healthy and diseased corneas, with special emphasis on changes seen in herpes zoster ophthalmicus, corneal and other therapeutic ocular procedures, antiglaucoma medical therapy, aging, and diabetes. With its potential applications ranging from managing ocular-specific to systemic diseases, the study of corneal innervation has implications for future therapies extending beyond just the eye itself.

Keywords: corneal innervation; corneal sensation; ophthalmic disease; ophthalmology; subbasal nerve plexus.

Figure 1

Diagrammatic representation of human corneal nerves. Reprinted from [5], with permission from Elsevier®.

Figure 2

In vivo confocal microscopy images of the subbasal corneal nerve plexus in eyes with herpes zoster ophthalmicus (HZO) and controls. Both the eyes affected by HZO (A) and the contralateral clinically unaffected eyes (B) demonstrated a significant reduction in subbasal nerve plexus including number of nerves, branches, and total nerve length when compared to normal controls (C). Reprinted from [51], with permission from Elsevier®.