Update on corneal neurotisation

Abstract

Corneal neurotisation describes surgical restoration of nerve growth into the cornea to restore corneal sensation and trophic function. It represents an exciting and effective emerging treatment for neurotrophic keratopathy. Techniques described to date involve either direct nerve transfer or an interpositional nerve graft coapted to a healthy donor nerve. We review the experience to date with particular emphasis on a detailed review of techniques, outcomes and current thoughts.

Corneal Neurotization and Novel Medical Therapies for Neurotrophic Keratopathy

“…NK can be unilateral or bilateral and can result from any cause that leads to injury or impairment of the trigeminal nerve or one of its branches, specifically the ophthalmic branch [7]. Common causes include herpetic keratitis; systemic diseases such as diabetes mellitus, multiple sclerosis, and leprosy; chemical and thermal eye injury; long-term contact lens use; topical anesthetic abuse, injury to the trigeminal nerve secondary to an intracranial space-occupying lesion, such as an acoustic neuroma; nerve transection secondary to anterior segment surgery or refractive surgery; or neurosurgical procedures that damage the trigeminal ophthalmic branch [4,5,7,15,16].…”

“…CN has shown success at restoring corneal sensation by reinnervating the stromal and sub-basal layers of the cornea, with a metareview of 54 eyes showing significant improvement in both best-corrected visual acuity (BCVA) and corneal sensation following neurotization [20••, 21]. This surgical approach has been demonstrated in both humans and animal models to effectively protect the cornea from ulceration and perforation and to promote faster epithelial healing compared to nonneurotized neurotrophic corneas [3,5,10,11,[22][23][24]. Since CN was first introduced by Terzis et al in 2009 [10], a series of adaptations and new techniques have evolved.…”

“…The SN graft has the ability to provide over 20 cm in length, which expands the donor nerve options to include the maxillary and mandibular branches of the trigeminal nerve [33]. Reports using the SN graft to the SON or STN demonstrate improvement in corneal healing, corneal sensation, and BCVA [5,24,33].…”

“…Fibrin is quick and easy to apply, but if used alone it may weaken before nerve healing is complete, leading to nerve gaps and resulting failed neurotization [5,13,34]. Nerve wrap options include amniotic membrane, porcine extracellular matrix, and absorbable collagen implant, which can be applied with fibrin glue and has anti-inflammatory properties that can reduce adhesions and scarring at the neurorrhaphy site [3,5,27]. At the corneoscleral limbus, some surgeons secure the nerve fascicles to the perilimbal episcleral space using absorbable or non-absorbable 8-0 to 10-0 sutures [25,35].…”

“…The cornea is innervated by the ophthalmic division of the trigeminal nerve (cranial nerve V). Approximately 50-450 sensory trigeminal neurons emanate from the ophthalmic branch and terminate as free nerve endings within the corneal epithelium [2,5]. Nerve fibers extend from trigeminal ganglion cells and branch into nerve bundles that lay uniformly around the corneoscleral limbus, forming the limbal plexus.…”