2 - Cornea and Sclera Flashcards
What is the radius size of the cornea?
8 mm
What is the radius size of the sclera?
12 mm
What is the radius of curvature of the anterior part of the cornea?
7.8 mm
What is the radius of curvature of the posterior part of the cornea?
6.5 mm
What is the central corneal thickness?
0.53 mm
What is the periphery corneal thickness?
0.71 mm
What is the profile description of the Cornea?
Elliptic
What type of astigmatism could be characterized if the Rx. would be within 90 degrees?
Irregular Astigmatism
True or False. The Cornea is vascular.
False.
Since the anterior part of the Cornea is covered by a tear film. What is the posterior bordered with?
Aqueous filled anterior chamber
Name the 5 layers of the Cornea.
Epithelium, Bowman’s Layer, Stroma, Descemet’s membrane and Endothelium
Approx. how many cells thick is the outer most layer of the stratified corneal epithelium?
5 to 7 cells thick
The surface later of the corneal epithelium is __ cells thick.
2
True or False. Non keratinized squamous cells contain an oval nucleus.
False. It is a flattened nucleus
What product is secreted that adjoins the mucin layer of the tear film?
Glycocalyx
In regards to Zonula Occludens, does fluid go between the cells or through them?
Through them.
The middle layer of the corneal epithelium is made up of what cells and how many layers do they consist of?
Wing cells. 2 to 3 layers worth.
What is the distinct shape of a wing cell?
Polyhedral
What type of cells occupy the innermost layer of the corneal epithelium?
Basal cell layer
Note: It is composed of a single layer of columnar cells and have oval shaped nucleus
What type of junctions, namely 2, join together columnar cells?
Desmosomes and gap junctions
Out of the 3 layers of the epithelium, which layer does mitosis only occur?
Basal cell layer
What holds together keratin filaments in the basement membrane?
Hemidesmosomes
Where does cell proliferation occur in regards to epithelial replacement?
Basal Layer
What is the time frame for the turnover of the entire corneal epithelium?
7 days
What is recurrent corneal erosion?
Condition in which the corneal epithelium sloughs off either continually or periodically.
What is Bowman’s layer mainly consist of?
Interwoven collagen fibrils within a mucoprotein ground substance
