Contents: 1. Introduction 2. Neuroanatomy of the corneal nerves 2.1. Embryology and development of corneal innervation 2.2. Origin of corneal nerves 2.3. Corneal nerve architecture 3. Neurochemistry of the cornea (Neurotrophins, Neurotransmitters and Neuropeptides) 4. The role of corneal nerves 4.1. Sensory and reflex function 4.2. Axonal reflex and neurogenic inflammation 4.3. Trophic function 5. Manifestations of corneal nerve dysfunction 5.1. Definitions 5.2. Corneal pain in the absence of ocular surface disease "Pain without stain" 5.3. Anaesthetic cornea with intact corneal nerves (pre-ganglionic damage) 5.4. Anaesthetic/hypoesthetic cornea with absent nerves and abnormal ocular surface "neurotrophic keratopathy, stain without pain" 6. Visualisation of corneal nerves 6.1. In vitro/ex vivo techniques 6.2. In vivo techniques: In vivo confocal microscopy (IVCM) 7. Nerve affection in corneal pathology 7.1. Post-surgical conditions 7.2. Diabetic Keratopathy 7.3. Herpetic corneal disease 7.4. Dry eyes 7.5. Keratoconus 7.6. Contact lens wear 7.7. Bullous keratopathy 7.8. Neurotrophic keratopathy (NK) 7.9. Glaucoma 7.10. Corneal dystrophies 7.11. Limbal stem cell deficiency 7.12 Small-fibre sensory neuropathy (SFSN) 79 8. Future directions 9. Funding support 10. Acknowledgement 11. References 12. Figure legends

No abstract

Aims To comprehensively study the gross anatomy of human corneal innervation. Methods Twenty-one specimens, including 12 normal human corneas from seven deceased patients, two eyebank corneo-scleral buttons, two eye-bank corneo-scleral rims and five post-surgical specimens from three patients with keratoconus were studied. Corneal whole mounts were stained for cholinesterase enzyme using the Karnovsky & Roots direct colouring thiocholine modification of acetylcholinesterase (AchE) technique.