Corneal Regeneration Flashcards
What happens to the cornea if the epithelium basement membrane or hemidesmosomes are damaged?
Can take months to heal completely.
If hemidesmosomes are malformed, which usually connect cells to the basement membrane, then this can lead to recurrent corneal erosion (RCE).
RCE
Recurrent corneal abrasion- when the corneal epithelium sloughs off continually
What happens if the cornea and corneal sensory nerves are damaged?
This would impair wound healing. CN V signals to the brain that mitosis needs to occur when corneal epithelium is damaged. If CN V is damaged, the corneal epithelium may not heal as quickly.
K
Cornea
What dye is used to see K abrasions?
Sodium fluoroscene, which is yellow, along with a cobalt blue light. If the dye pools in area of abrasion, it will display green (yellow+blue).
What layers of the cornea do not regenerate?
Bowman’s layer and the endothelium
What happens if Bowman’s layer is damaged
It will not regenerate. It will be replaced by epithelial cells or stoma-like fibrous tissue= collagen. This may cause scarring if collagen isn’t organized. However, it is very resistant to damage.
What happens if the stroma is damaged?
It will regenerate, but the newly formed connective tissue (collagen) will differ slightly from the original tissue. It won’t be as perfect, and this may cause scarring or opacification.
Scars that form in the stroma always appear to be which shape
Circular
What happens if Descemet’s membrane is damaged?
(Vary rare to damage Descemet’s)
Can be secreted and re-formed by stromal keratocytes and endothelium.
If a hole is formed, it will allow a lot of water to enter the cornea since it is the basement membrane of the endothelial cells.
What happens if endothelial cells are damaged
They do not regenerate. With cell loss, neighboring cells generally enlarge and flatten to cover the area loss.
Results in enlarged endothelial cells (polymegathism) and irregularly shaped cells (pleomorphism).
Can result in stromal edema.
How does endothelial cell numbers change with age
Cell density decreases with age due to cell disintegration.
As a child, have around 3-4k cells/mm^2
At age 80, have around 1-2k cells/mm^2
Technically, only need 400-700 cells/mm^2
What endothelial cell density is needed for adequate function?
400-700 cells/mm^2
Loss of endothelial cells beyond this can result in stromal edema.
Fuch’s dystrophy
Loss of endothelial cells, so more water is able to enter into the cornea. This results in vision blur.
Enlarged endothelial cells
Polymegathism
