Lecture 11 - Eye Pathology

Question 1

Describe sympathetic innervation in the IRIS

Answer 1

Pupil dilation - CONTRACTION of radial dilator smooth muscle
Produces NA which will bind to alpha1adrenoceptors

Question 2

Describe the parasympathetic innervation in the IRIS

Answer 2

Pupil constriction - CONTRACTION of sphincteric constrictor smooth muscle
Parasympathetic nervous system produce Ach which is working at M3 muscarinic receptors

Question 3

What signalling is dominant in the eye?

Answer 3

Parasympathetic

Question 4

What are the two types of smooth muscle in the eye?

Answer 4

1) Iris Smooth muscle
- dilator
- sphincter
- regulates pupil size and hence the amount of light reaching
2) Ciliary muscle
- changes refractive index of lens accommodation
- control the shape if you can’t change the shape that you will not be able to see

Question 5

What happens to your pupil with bright light?

Answer 5

Miosis, the pupil gets smaller

Question 6

What happens to your pupil with low light?

Answer 6

Mydriasis, pupil gets bigger

Question 7

Give an example of a muscarinic agonist

Answer 7

Pilocarpine

Question 8

Give an example of a muscarinic antagonist

Answer 8

Atropine

Question 9

Where is AH produced by?

Answer 9

Ciliary Body Epithelium
Flows from the posterior chamber through the iris into the anterior chamber
=> Trabecular Meshwork (90%), Canal of Schlemm and into vein
=> Uveoscleral outflow (10%)

Question 10

What is AH composed of?

Answer 10

Ultrafiltration of plasma
Produces nearly protein free-liquid
High levels of lactate due to anaerobic glycolysis - high amount of bicarbonate
High level of ascorbic acid (antioxidant) - protects against UV radiation - causes the formation of free radicals

Question 11

What is atropine used to treat?

Answer 11

Amblyopia (lazy eye)
Contraindication - closed angle glaucoma (impairs the drainage of AH) - good eye is treated to push the lazy eye to work