The molecular basis of neurotrophic keratopathy: Diagnostic and therapeutic implications. A review

Neurotrophic keratopathy (NK) is a degenerative corneal disease produced by different factors, including infection, trauma, and neurogenesis, that lead to trigeminal nerve damage and impaired corneal sensitivity. Extensive epithelial breakdown, impaired corneal epithelial healing and corneal ulceration, stromal melting, and perforation are main NK features. The proliferation of the corneal epithelium is endogenously regulated by a balance between adrenergic cAMP-dependent and cholinergic cGMP-dependent pathways. A careful balance of epitheliotropic neuromediators and neurotrophic factors expressed by corneal nerves and epithelial cells, respectively, is required to maintain corneal homeostasis. Even in its early stages, NK can cause reduced vision secondary to epithelial disturbance. Diagnosing NK is challenging, requiring the acquisition of a thorough clinical history and a comprehensive neurological and ophthalmic examination. Following suspicion of a clinical NK diagnosis, corneal sensitivity must be assessed qualitatively with the wisp of the cotton-tipped applicator and quantitatively through Cochet-Bonnet esthesiometry (CBE). A myriad of therapies is used for NK, and new, more specific modalities are being developed and investigated. Medical treatment with topical recombinant human nerve growth factor and surgical treatment through corneal neurotization are promising therapies aiming to target NK pathophysiology. Coexistent ocular surface disorders must be managed concomitantly to improve its prognosis. This review describes the up-to-date knowledge of the molecular basis regarding the pathogenesis of NK, and the novel target-specific therapeutic approaches based on this molecular mechanism.