Cornea - Recit Flashcards
What are the layers of the cornea?
ABCDE
1. (Anterior) Epithelium
2. Bowman’s Layer
3. Corneal Stroma
— Dua’s layer—
4. Descemet’s Layer
5. Endothelium
Function of Epethilium
1.to obstruct the passage of foreign materials (dust, bacteria) from penetrating the layers of the cornea
2. to absorb oxygen and nutrients from the eye’s tears to provide a smooth surface layer. The nutrients that are absorbed from the tear layer are distributed to the remainder of the cornea via the epithelium
Function of Bowman’s Layer
Structurally reinforces the cornea
Basement membrane of the epithelium; transparent sheet composed of collagen fibers
Bowman’s Layer
Does not get damaged easily but cannot be regenerated once damaged
Bowman’s Layer
Comprises 90% of the Cornea’s thickness. It consists mainly of 78% water and 16% collagen. Does not contain any blood vessels.
Corneal Stroma
Function of Descemet’s layer?
Serves as a protective barrier against infection and injuries
Anchors the endothelium to the cornea, while simultaneously allowing the entry od nutrients and macromolecules into the corneal stroma
Descemet’s Layer
Function of the endothelium?
Essential in keeping the cornea clear as it pumps excess fluid out of the stroma. Without it’s pumping action, stroma would swell w/ water, become hazy, and ultimately opaque
Endothelium once gone, is lost forever
Blood supply of the Cornea?
The cornea is avascular to keep it clear. Thus, it receives nutrients via diffusion from the tear fluids and the aqueous humor + the neutrophins from nerve fibers. It receives oxygen directly from the air.
blood vessels of the eyelid
Innervations of the cornea?
70 to 80 large nerves + 7000 epithelial nerve endings
- Long and shor Ciliary Nerves
- Opthalmic branch of CN #5
