Cornea Anatomy Flashcards
Tear film index?
n=1.336
Cornea index?
n=1.376
Where is the cornea thickest?
PERIPHERY (0.67mm)
vs center (0.55mm)
Anterior radius of curvature for the cornea?
7.8mm
Posterior radius of curvature for the cornea?
6.5mm
Avg ant H and V diameter of cornea?
- 7 mm H
10. 6 mm V
How thick is corneal epi?
50 um
What connect basement membrane to corneal epi?
Hemidesmosomes
How thick is bowman’s layer?
12 um
NOTE: will scar
How thick is stroma?
450 um
NOTE: keratocytes
How thick is descemet’s?
5-15 um
NOTE: born w 5um die w 15
Endothelium thickness?
5um
NOTE: most mitochondria and pumps located here
Which is the ONLY layer in the cornea to contain zonula occludens?
Corneal Epithelium
NOTE: zonula occludens/tight junctions and desmosomes form a tight barrier btwn cells to impede the intercellular movement of particles
What are wing cells joined by?
Desmosomes
What is the only miotic layer of the corneal epithelium?
Basal layer
NOTE: this layer divides into wing and hemidesmosome
Limbal stem cell deficiency contributes to poor corneal epithelial maintenance in people with what diseases?
- Aniridia
- SJS
- Alkali corneal burns
What are the 2 layers in all basement membranes of the body?
- Basal lamina (secreted by epi cells)
2. Reticular lamina (produced by underlying stromal cells)
What are the 3 risks for recurrent corneal erosions?
- Poor hemidesmosome attachments
- Epithelial BM dystrophy
- Age related thickening of the BM
What type of collagen is Bowman’s composed of?
Type 1 collagen
NOTE: acellular layer
What are conditions related to Bowman’s layer?
- Band keratopathy
- Pterygium
- Crocodile Shagreen
- Reis-buckler’s dystrophy
- Keratoconus (T-DOME)
- Refractive Sx
What collagen is corneal stroma composed of?
Type 1
What produces the collagen in corneal stroma?
Keratocytes
NOTE: these also make ECM
How are corneal stroma fibrils spaced?
Evenly by 30nm lamellae
What does the ground substance in stroma function to do?
Contain GAGs which attract water creating PERFECT spacing
NOTE: the predominant GAG is keratin sulfate
What type of collage in descemet’ membrane made of?
Type 4
What are the disorders related to descemet’s membrane?
- Hydrops
- Haab’s striae
- Hassall-Henle Bodies
What kind of cells is endothelium made of?
Squamous cells
NOTE: These epithelia are common where absorption or transport of materials is important. They also play a role in diffusion, osmosis and filtration. This makes them important in the kidney, in the alveoli of lungs and in the walls of capillaries.
How are endothelium linked together (apical or basal)?
Apical borders facing anterior chamber by MACULAE OCCLUDENS (leaky)
Where does the corneal get nutrients from?
- Diffusion from aqueous humor
- Limbal conj and episcleral cap networks
- Palpebral conj networks
Where is the main source of O2 to the cornea during sleep?
ANTERIORLY=palpebral conj
POSTERIORLY=aqueous
Where does the LPCN and SPCN enter the cornea?
MID-STROMA
After traveling into the stroma, what happens to the corneal nerves?
They lose their myelin sheath
Now they are HIGHLY SENSITIVE AND NAKED w nociceptors that mediate pain
Where are nerve networks formed?
- Epithelium - Intraepithelial plexus
- Anterior Stroma/Bowman’s Layer - Subepithelial plexus
- Mid stroma - stromal plexus
