Ocular Disease: Lecture 9: Cornea Flashcards
1
Q
Cornea
- It’s the most densely what in the body?
- a. Length: Horizontally?
b. Vertically?
c. Thickness?
d. Where is it thickest?
A
- Most densely innervated tissue in the body
- a. 12 mm
b. 11.5 mm
c. 540 microns thick
d. in the Periphery
2
Q
Cornea: Layers
- What are the 5 layers
A
- Epithelium
- Bowman’s Layer
- Stroma
- Descemet’s Membrane
- Endothelium
3
Q
Cornea: Epithelium Layer
- 3 Types of cells?
A
- Columnar Basal Cells; Wing Cells; Surface Squamous Cells
4
Q
Cornea: Epithelium Layer
- What are Columnar Basal Cells attached to?
- What happens to the Surface Squamous Cells?
A
- To the Basement Membrane
2. They’re SHED into the TEAR FILM after 2-3 Days
5
Q
Cornea: Bowman’s Layer
- What is it?
- What is it made of?
A
- It’s an ACELLULAR Superficial Layer of the Stroma
2. Collagen Fibers
6
Q
Cornea: Stroma
- % of the thickness of the Cornea?
- Type of orientation of the Collagen Fibers?
- Does it regenerate?
- What else is found here?
A
- 90% of the corneal thickness
- Regularly Oriented Layer of the Collagen Fibers
- NO!
- Modified Fibroblasts are INTERSPERSED
7
Q
Cornea: Descemet’s Membrane
- What is it?
- How many zones and what are the zones?
A
- Sheet of Collagen Fibrils
2. 2 Zones: Anterior Banded, and Posterior Non-Banded
8
Q
Cornea: Descemet’s Membrane: 2 Zones
- Anterio Banded is what?
- Posterior Non-Banded: What is it?
a. Can it regenerate?
A
- In-Utero
- Endothelial Basement Membrane
a. YES!!!
9
Q
Cornea: Endothelium
- Type of Cells and layers?
- What does it help Maintain?
- Number of Cells /mm^2?
a. How many are lost each Year? - What happens when you get 500 cells/mm^2?
A
- Single Layer of POLYGONAL CELLS
- The State of Corneal Hydration! (Pumps fluid OUT of the Cornea)
- 2500 cells/mm^2
a. About 0.6% each year - Corneal Edema and Decreased Transparency
10
Q
Cornea: 6th Layer?
- How long ago was it discovered?
- Discovered by whom?
- What do they think it is?
a. Cellular?
b. Thickness? - How was it discovered?
- What do they think it’s important for?
A
- It’s a RECENTLY described “New” Layer. Called the DUA’s LAYER
- Harminder Dua and Perry Binder
- Very Strong Pre-Descemet’s Layer
a. Acellular
b. 10-15 microns Thick - Using the Big Bubble Technique
- For Lamellar Surgeries
11
Q
Cornea: A lot of Important Clinical Findings? (8)
A
- PEE
- PEK
- SEI
- SPK
- Filaments
- Edema
- Neovascularization
- Pannus
12
Q
Cornea: Superficial
- Punctate Epithelial Erosions (PEE): It’s an Early sign of what?
- What is it?
A
- of Epithelial Compromise
2. Tiny Defects (NaFl; Rose Bengal are the way to see them!)
13
Q
Cornea: Superficial: PEE
- Location may indicate cause? (5 different places)?
A
- Central
- Diffuse
- Inferior
- Interpalpebral
- Superior
14
Q
Cornea: Superficial: PEK
- What is it?
- Can you see it w/o Staining?
- What will you see?
A
Punctate Epithelial Keratitis (PEK)
- Granular Swollen Epithelial Cells
- YES
- DISCRETE OPACITIES (Intra-Epithelial Infiltrates)
15
Q
Cornea: Superficial: PEK
- Cases?
A
- Non-Specific: Seen in a wide variety of Conditions
16
Q
Cornea: Superficial: SEI
- What does SEI stand for?
- What is it?
- Where is it located?
- Can you stain it?
A
- Sub-epithelial Infiltrates (SEI)
- Tiny Focal Inflammatory Infiltrates
- They’re Just below the Surface
- No. Non-Staining
17
Q
Cornea: Superficial: SEI
- Causes? (4)
A
- Acne Rosacea
- Herpes Zoster
- Prolonged Viral Infection
- Other INFLAMMATORY CONDITIONS!!!
18
Q
Cornea: Superficial: SPK
- What does SPK stand for?
- ONLY refers to LESIONS ASSOCIATED with what?
- What is it?
- Where is it found?
- Staining?
A
- Superficial Punctate Keratitis
- with THYGESON
- Course Punctate Grayish white clusters of Epithelial Lesions
- Central and Elevated
- Possible Negative Staining