Applied Anatomy & Physiology of the Eye

Question 1

What are the 5 layers of the cornea

Answer 1

1) Non keratinised, stratified squamous epithelium
2) Bowmans membrane- basement membrane
3) Stroma- connective tissue- regular layers of collagen which allow for corneal transparency
4) Descemet’s membrane-
5) Endothelium- single layer (2500 cells/mm^2

Question 2

Where do the nutrients for the cornea come from

Answer 2

• Aqueous humour

- Capillaries at the peripheries of the cornea

Question 3

How is the transparency of the cornea maintained

Answer 3

1) No blood vessels in cornea
2) Endothelium pumps out the aqueous humour
3) Arrangement of the stroma

Question 4

Why is the avascularity of the cornea ideal for corneal transplants?

Answer 4

Immune-privellaged site

Unlikely for there to be organ rejection

Question 5

State layers 1,2 & 9 of the retina (most important ones)

Answer 5

1. Peripheral epithelial layer
2. Layer of rods and cones
3. Nerve fibre layer

Question 6

What is the fovea centralis

Answer 6

Spot in the retina which has the highest visual acuity
Packed with cones
10 layers are very thin so light can come in very easily

Question 7

What is the lens

Answer 7

Biconvex structure with transparent crystals

Question 8

Why is the lens more prone to become opaque in comparison to the cornea

Answer 8

Avascular

Gets all of its nutrients from aqueous humour and vitreous humour

Question 9

What is the function of the tear film

Answer 9

Keeps cornea moist and washes away foreign bodies
Has lysosomes
Makes outer surface of the eye smooth

Question 10

State the three layers of the tear film and where they are secreted from

Answer 10

1. Mucinous layer
2. Aqueous layer- comes from the lacrimal gland
3. Oily layer- comes from meibomian gland

Question 11

What nerve causes the secretion of tears into the conjunctival sac

Answer 11

Parasympathetic Facial nerve (VII)