130 Sudden visual disturbance

Question 1

Where in the retina are cone cells predominantly found?

Answer 1

Centrallly - highest at the fovea

Question 2

Where in the retina are rod cells predominantly found?

Answer 2

In the periphery

Question 3

Which cells of the retina are responsible for the ‘sensor surround effect’?

Answer 3

Horizontal cells

Question 4

Where in the brain do ganglion cells project to?

Answer 4

Suprachiasmatic nuclei

Question 5

Which cells contain melanopsin?

Answer 5

Retinal ganglion cells

Question 6

Which photopigment is involved with the regulation of circadian rhythm?

Answer 6

Melanopsin

Question 7

Explain the phototransduction pathway

Answer 7

• light hits rhodopsin and 11-cis-retinal in the disc of rod cell
• change in conformation –> all-trans-retinal
• transducin detaches –> α subunit binds to phosphodiesterase
• phosphodiesterase changes cGMP –> GMP
• Na⁺ channels close as cGMP no longer bound
• no Na⁺ means hyperpolarisation = off –> which turns bopolar cells on
• signal transduction

Question 8

What is RAPD?

Answer 8

Relative afferent pupil defect - lesions anterior to the chiasm eg in neuritis and MS

Question 9

What is protanopia?

Answer 9

Red visual weakness

Question 10

What is deutranopia?

Answer 10

Green visual weakness

Question 11

What is tritanopia?

Answer 11

Blue visual weakness

Question 12

Which nucleus in the mibrain is involved in the visual pathway?

Answer 12

Edinger-Westphal

Question 13

Where do the oculomotor efferents synapse with short ciliary nerves?

Answer 13

Ciliary ganglion

Question 14

Loss of vision in the right eye - where in the visual pathway is the defect?

What could cause this?

Answer 14

Right optic nerve

• compressive tumour
• optic neuritis
• anterior ischaemic optic neuropathy

Question 15

Loss of peripheral vision - where in the visual pathway is the defect?

What could cause this?

Answer 15

Defect in the optic chiasm

• Parasellar mass

Question 16

Loss of nasal vision in the R eye and loss of temporal vision in the L eye - where in the visual pathway is the defect?

What could cause this?

Answer 16

Defect in the right optic tract

• neoplasm
• inflammatory process
• arteriovenous malformation

Question 17

Loss of vision in the upper left quadrant of L and R eyes - where in the visual pathway is the defect?

What could cause this?

Answer 17

Lesion in the upper right optic radiations

• neoplasm
• inflammatory process
• ischaemia
• infection

Question 18

What protective molecules/cells are in tears?

(7 listed)

Answer 18

1. Lactoferrin
2. lysozyme
3. β-lysin
4. IgA
5. IgG
6. complement
7. leukocytes

Question 19

What causes primary open angle glaucoma?

Answer 19

Decreased outflow of aqueous humour through tebecular meshwork

Question 20

What is timolol and what is it used to treat?

Answer 20

β- blocker used to treat primary open angle glaucoma

Question 21

Where is the vision loss in age related macula degeneration?

Answer 21

Central

Question 22

What are drusen and in which condition are they found?

Answer 22

Lipfuscin deposits - found in dry macula degeneration

Question 23

What is the cause of wet macula degeneration?

Answer 23

Neovascularisation from the choroid layer which has severe impact on central vision

Question 24

How does lucentis work in macular degeneration?

Answer 24

Binds to VEGF-A which prevents it from binding to its receptor. Normally involved with neovascularisation and angiogenesis

Question 25

Which receptors does phenylephrin act on?

Answer 25

α1 receptors

Question 26

What is the effect of topical application of phenylephrin on the eye?

Answer 26

Myadriasis - dilation of the pupil

Question 27

Why is phenylephrin less effective in: * diabetes * dark irises * elderly

Answer 27

* increased glucose makes the pupillary muscles less flexible * lots of melanin which phenylephrin binds to * lots of wear and tear

Question 28

What are the SE of phenylephrin? | (5 listed)

Answer 28

* photophobia and blurred vision * stinging * acute glaucoma * HTN * arrhythmias

Question 29

Name 3 antimuscarinics which causes myadriasis

Answer 29

1. Atropine 2. Cyclopentolate 3. Tropicamide

Question 30

What are the benefits of using tropicamide to cauase myadriasis?

Answer 30

Quick and short-acting

Question 31

What are the systemic effects of tropicamide, atropine and cyclopentolate? Action on which receptors cause this?

Answer 31

* Dry mouth * Flushing * Confusion Act to block ACh at muscarinic receptors

Question 32

Which eye drugs can raise IOP?

Answer 32

Antimuscarinics, sympathomimetics

Question 33

What drug is used in the treatment for glaucoma? MOA?

Answer 33

Pilocarpine - mimics ACh on muscarinic receptors which causes miosis and opens up the drainage of the trabecular network. Reverses myadriasis in 30-60mins

Question 34

Which parasympathomimetic eye drug inhibits the production of aqueous humor?

Answer 34

Timolol

Question 35

What is the MOA of the sympathomimetic eye drug acetazolamide?

Answer 35

Inhibits carbonic anhydrase which is needed for the production of bicarbonate in aqueous humor

Question 36

What is hypromellose the 1st line treatment for?

Answer 36

Artificial tears

Question 37

What are the red flag symptoms suggestive of acute closed angle glaucoma?

Answer 37

* red, painful eye * N&V * blurred vision * headache

Question 38

Which antibiotic can cause orange tears?

Answer 38

Rifampicin

Question 39

Which is the most appropriate abx for the treatment of a *Pseudomonas* infection of the eye + corneal ulcer? * chloramphenicol * gentamycin * ciprofloxacin

Answer 39

Ciprofloxacin

Question 40

Which is the most appropriate abx for the treatment of a *Pseudomonas *infection of the eye? * chloramphenicol * gentamycin * ciprofloxacin

Answer 40

Gentamycin

Question 41

Which is the most appropriate abx for the treatment of a *Staphylococcus* infection of the eye. * chloramophenicol * gentamycin * ciprofloxacin

Answer 41

Chloramphenicol