CORNEA

Question 1

is a complex structure which contributes in the optical power of the eye

It is free of blood vessels- avascular

Its nutrients are supplied and metabolic products removed mainly by the aqueous humor posteriorly and tears anteriorly

It is the most densely innervated tissue in the body

Answer 1

Cornea

Question 2

Cornea Average diameter

Answer 2

11.5 mm vertically and 12 mm horizontally

Question 3

Average center thickness

Answer 3

540 µm and thicker towards the periphery

Question 4

stratified squamous and non-keratinized; the surface area of the outermost cells has microplicae and microvilli which facilitates in tearfilm (mucin) adhesion

Answer 4

Eptihelium

Question 5

acellular superficial layer of the stroma formed from collagen fibers

Answer 5

Bowmans layer/membrane

Question 6

makes up the 90% of the cornea’s thickness; it is arrange in regularly oriented layers of collagen fibrils whose spacing is maintained by proteoglycan (chondrointin sulphate & keratan sulphate); its arrangement and spacing of collagen is critical for the cornea’s optical property; it does not regenerate

Answer 6

Stroma

Question 7

is a discrete sheet composed of fine latticework of collagen fibrils that are distinct from the collagen of the stroma; it has regenerative potential

Answer 7

Descemet membrane

Question 8

consists of monolayer of polygonal cells; it pumps excess fluid out of the stroma; the number of cells decreases at about 0.6% each year and it does not regenerate thus causes corneal edema and transparency is reduced

Answer 8

Endothelium

Question 9

tiny epithelial defects that stain with fluorescein dye and rose Bengal

Answer 9

Punctuate Epithelial Erosiona (PEE)

Question 10

granular, swollen epithelial cells; can be visible without staining

Answer 10

Punctuate Epithelial Keratitis

Question 11

tiny subsurface foci

Answer 11

Subepithepial Infiltrates

Question 12

dot-like morphology

Answer 12

Superficial Punctuate Keratitis

Question 13

strands of mucus admixed with epithelium, attached at one end to the corneal surface; the unattached end moves with every blink

Answer 13

Filaments

Question 14

• Composed of stratified squamous non-keratinized
  epithelial cells that are easily abraded
• Though epithelial injuries are painful, this layer heals
  quickly and typically does not scar

Answer 14

corneal epithelium

Question 15

• Anterior limiting membrane of the cornea that provides

protection to the stroma

Answer 15

Bowman’s layer

Question 16

• Makes up 90% of the corneal thickness
• Transparent later composed of a regularly arranged
  collagen fibers
• Once this layer is damaged, this can lead to scar
  formation

Answer 16

Corneal stroma

Question 17

• Basal lamina of the endothelium

- Posterior limiting membrane

Answer 17

Descemet’s layer

Question 18

• Single layer of cells
• Regulates fluid exchange between cornea and
  aqueous
• Maintains dehydration

Answer 18

Endothelium