CORNEA

Question 1

CORNEA

Answer 1

• transparent, avascular connective tissue with a smooth surface
• refracting surface
• main barrier to infections
• continuous with conjunctiva + sclera

Question 2

CORNEA REFRACTIVE POWER

Answer 2

approx 2/3 of eyes total refractive power

43D

Question 3

REFRACTIVE INDEX OF CORNEA

Answer 3

1.33

Question 4

SHAPE OF ANTERIOR SURFACE

Answer 4

CONVEX + ELLIPTICAL

Question 5

WHAT DOES IT MEAN BY CORNEA IS PROLATE?

Answer 5

steeper centrally, flatter peripherally

Question 6

3 MAIN CORNEA CELL TYPES

Answer 6

• epithelial
• stromal keratocytes
• endothelial

Question 7

CORNEA STRUCTURE

Answer 7

- epithelium 
(many layers)
- bowman’s membrane (amorphous collagen)
- stroma 
(collagen matrix with keratocytes)
- descemet’s membrane 
(unstructured collagen)
- endothelium 
(cell monolayer)

Question 8

CORNEAL EPITHELIUM

Answer 8

• outermost layer
• 5-7 cell layers thick
• epithelial cells replaced every week
• superficial squamous cells, intermediate wing cells + innermost cuboidal cells

Question 9

MUCIN IN CORNEAL EPITHELIUM

Answer 9

coat microplicae - forms innermost layer of tear film - smooths out epithelial microirregularities

Question 10

MICROPLICAE

Answer 10

small projections on squamous cell surfaces

Question 11

CORNEAL EPITHELIUM SUPPORTED ON WHAT?

Answer 11

BASEMENT MEMBRANE

Question 12

SUPERFICIAL SQUAMOUS CELLS ON CORNEA LINKED BY?

Answer 12

ANCHORING JUNCTIONS (tight or zonula occludens) - prevents tear film inflow