Ch. 2 Cornea and Sclera Flashcards
(19 cards)
ROC of cornea =
ROC of sclera =
8 mm
12 mm
Dimensions of globe?
24 mm antero-posterior
23 mm vertical
23.5 mm horizontal
Anterior horizontal diameter of cornea =
Anterior vertical diameter of cornea =
12 mm
11 mm
T/F: Curvature of cornea steeper in the center and flatter near the periphery
T
ROC of central cornea =
ROC of posterior cornea =
- 8 mm
6. 5 mm
Central corneal thickness =
Corneal periphery =
- 53 mm
0. 71 mm
WTR
Steepest curvature in the 90 = shortest ROC
ATR
Horizontal meridian the steepest
5 layers of the cornea:
- Epithelium
- Bowman’s
- Stroma
- Descemet’s
- Endothelium
Outermost layer of stratified corneal epi is ___-7 cells thick and measures ___
5; 50 um
Surface epi cells secretes ___
Glycocalyx - adjoins mucin layer of the tear film
___ joins the surface cells - prevents uptake of excess fluid from the tear flim
Zonula occludens
T/F: As surface cells age, they degenerate, shed into the tear film and are replaced from the layers below.
T
Middle layer of the corneal epi is made up of 2-3 layers of ___
Wing cells (20 um)
Innermost layer of corneal epi:
Basal cell layer - secrete basement membrane which attaches the cells to the underlying tissue via hemidesmosomes
If tight junctions are disrupted, fluorescein dye passes easily through Bowman’s layer and into the ___
Stroma - defects will appear vivid green
Renewal of stratifed epi involves:
Cell division, migration, differentiation and senescence
Proliferation occurs in the basal layer >
Wing cells > surface cells
Turnover time for entire corneal epi is approx ___ days
7
