Lecture 13.2 Cornea Anatomy (nerve supply, vessels, limbus)

what is the corneal nerve supply

Long posterior ciliary nerves and anterior ciliary nerve from ophthalmic division of trigeminal nerve

what does the corneal nerve supply form

an annular plexus at limbus

how does the corneal nerve supply enter the cornea

in radial pattern within anterior stroma (~70-80)

length of myelinated corneal nerve supply

2-3 mm

when does corneal nerves lose their myelin and Schwann’s cells

As they form the sub-basal nerve plexus

why does corneal nerves lose myelin sheath as they travel from the peripheral stroma toward the center

for transparency and exquisite sensitivity of the cornea, but might retain Schwann sheath (neurolemma)

where does corneal nerve supply pierce through

bowman’s and basal lamina

how does the corneal nerve supply pierce through at bowman’s and basal lamina

they do a 90 degree bend to travel sideways, forming the subepithelial plexus. then do another 90 degree bend sends them to the surface

when the corneal nerves pierce the epithelial basement membrane to enter the anterior epithelium, what do they lose

the neurolemma sheath and end organs

purpose of the many nerve endings in corneal nerve supply

for exquisite sensitivity because nerve endings are now unmyelinated and lack a neurolemma or specialized end organs

what is the limbus of the eye

the transitional zone between cornea and conjunctiva, and between cornea and sclera.

what is the transitional zone between cornea and conjunctiva, and between cornea and sclera.

limbus

where is the limbus of the eye located

at the corneoscleral junction

what is the length of the limbus

It is a band approximately 1.5 to 2 mm wide that encircles

two parts of the limbus

Outer and Inner limbus

function of Vascular Endothelial Growth Factor (VEGF) in the limbus

surrounding ocular tissues promotes the formation of new blood vessels (angiogenesis) to supply oxygen

why do we find anti-VEGF (Vascular Endothelial Growth Factor) near the cornea

to keep the central cornea completely clear and free of blood vessels so light can pass through cleanly to the retina

where does the blood vessels stop in our eyes

limbus

where does nutrients come for the cornea

tear fluid and/or aqueous humor

what is the Neovascularization Pathway in Hypoxia (medical condition in which your body's tissues do not receive enough oxygen to maintain normal function) from EXTERNAL CAROTID ARTERY

External carotid artery → facial artery → angular artery → anterior conjunctival vessels → limbal vascular arcade → new corneal vessels (neovascularization)

what is the Neovascularization Pathway in Hypoxia (medical condition in which your body's tissues do not receive enough oxygen to maintain normal function) from INTERNAL CAROTID ARTERY

Internal carotid artery → ophthalmic artery → anterior ciliary arteries → episcleral & conjunctival capillaries → limbal arcade → corneal neovascularization