Applied anatomy and physiology of the eye

Question 1

5 layers in the cornea (histology)

Answer 1

epithelium
bowmans membrane
Stroma
Descemet’s layer
endothelium

Question 2

clls per mm2 in basement endothelium

Answer 2

2500

Question 3

AH pressure

Answer 3

21mmHg

Question 4

how can the cornea opacifyWhy don’t youhave to precicly match a corneal donor with the ecipient?

Answer 4

It can opacify if the endothelial cells that pump out the aqueous humour are reduced in number or damaged, allowing AH to enter into the corneum, thickening it anc causing opacities. The body then tries to heal and results in fibroblasts etc and opacity.

Corneal transplant doesn’t need to be precisly matched because tthe corneum is avascular and so no threat of having a bad reaction.

Question 5

INtraoccular pressure is controlled by what?

Answer 5

The Aqueous humour

Question 6

Where is the angle if the sclera? How is it observed?

Answer 6

It is the angle between the iris and the junction of the sclera and the corneum (where schlemms canal and the trabecular meshwork sits)

Observed through using another lens - gonioscopy

Question 7

WheHow do you get glaucoma?

Answer 7

increased intraoccular pressure, due to the Aqueous humour being unable to drain away, potentially because of adhesion of the iris to the perhiphery of the cornea. This is a “closed” angle of sclera and can increase the pressure. The extra pressure can kill the optic nerve ad lead to death of the cells and blindness

Question 8

Where are the layer of rods and cones, and pigment epithelial layer, nerve fubre layer/?

Answer 8

Choroid membrane - pigment epithelial layer - layer of rods and cones.

Then, closer to the vitrous humour (just under the inner limting membrane is the Nerve fibre layer)

Question 9

Blood supply of the inner layer of the retina? The layer of rods and cones?

Answer 9

Inner layer (nerve fibre layer) of the retina is supplied through central retinal artery (optalmic artery)

Outer layer (rods and cones) = Choroid (remember it’s sat on this very vascular layer

Question 10

Detached retina, where? WHy?

Answer 10

Between the layer of rods and cones and the pigment epithelial layer- due to embryology (shock horror), it is the surface between the 2 cups that go on to form the retina

Question 11

What is the Fovea centrals

Answer 11

The central part of the retina that has the most amount of cone cells and so will absorb and be the most focused focal part and is why we move our eye. Has the least amount of other layers aswell ontop of the rod and cone layer.

Question 12

What does the lens get its nuteints from? Opaque lens is called wat?

Answer 12

from the humours, so easy to have a lack of nutrients and get a CATARACT (opaque patches on the lens)

Question 13

What do tears drain into?

Answer 13

LAcrimal Punctae into the lacrimal sac

Question 14

WHat are the 4 functions of the tear film? And what are the 3 layers of the tear film?

Answer 14

Immune - contains lysozymes
Keeps cornea moist (prevents from drying out)
Washes away foreign bodies
smooths surface for refraction

3 layers =
-Mucinous layer (30%), overlies the corneal epithelium, needed fothe aqueous layer to sit on top of
-Aqueous layer = ontop of the mucinous layer (69%)
-Oily layer (1%)