Cornea Flashcards
Function of the Cornea ?
To allow light into the eye
To refract the light
Which part of the eye offers majority of the refractive power
Cornea
How do you calculate Surface power ( F )
F= (n’-n)/r
Where can the cornea be found
Sandwiched between the tear film anteriorly and the aqueous humour posteriorly
Explain the CCT (central corneal thickness)
It’s thicker at the periphery (sides) than it is at the centre
Why is CCT (central corneal thickness important)
When undergoing laser treatment to correct a patient’s refractive error, you’re required to remove some corneal thickness.
Therefore it’s important that you know how thick it is so you know if there’s a sufficient amount of corneal left to maintain stability in the eye
Explain the corneal shape
It is steepest at the centre and flattens peripherally
What is keratoscopy
The measurement of the corneal curvature at all points on the cornea
What is keratoconus
Pathological steepening and thinning of cornea
What is the cornea
A transparent window that protects the iris and pupil
How many corneal layers are there ?
Name them in order
There are 5 layers
Corneal epithelium Bowman’s membrane / layer Substantia propria / stroma Descemet’s membrane Corneal endothelium
The corneal epithelium is made up of what?
It is made up of 5/6 layers of cells that are completely replaced every seven days
The corneal epithelium is made up of three types of cells. What are they
Basal cells
Wing or Umbrella cells
Superficial or Squamous cells
How many days does it take for cells to move from the basal cells to the squamous cells
5-7 days
How does the corneal epithelium under for repair ( 3 steps)
- The basal cells stop mitosis
- There’s a centripetal slide of basal cells (moves to centre)
- There is cell growth at the centre of damage
