Opthamology 2 - Eye and Vision (special senses)

Question 1

What is visual acuity?

Answer 1

Ability of the visual system to resolve or see the gap between two object (spatial resolution)

Question 2

How is visual acuity measured?

Answer 2

• Snellen chart (6 metres)

- 6/x - x denotes the number of the line of the smallest text that was seen

Question 3

What visual acuity is considered ‘blind’ or Severe sight impairment (SSI)?

Answer 3

3/60 (ubake to see first letter on snellen within 3m)

Question 4

What visual acuity is needed for driving?

Answer 4

6/12 or better

Question 5

What is the parasympathetic motor element of the 3rd cranial nerve?

Answer 5

Edingar Westphal nucleus

Question 6

Where does the optic nerve synapse?

Answer 6

Pretectum in superior colliculus gives off information to both Edingar Westphal nuclei - precipitates a response down both nerves causing shpincters of the iris to constrict

Question 7

What does a swinging light test look for?

Answer 7

Relative afferent pupillary defect - defect in optic nerve of one side

Question 8

What are the causes of Relative Afferebt Pupillary Defects (RAPD)?

Answer 8

• Optic neuritis
• Anterior ischaemic optic neuropathy (AION) - associated with giant cell arteritis
• Tumour pressing on optic nerve
• Glaucoma

Question 9

What is a retinal reflection test looking for?

Answer 9

• Assess clarity of ‘media’
• Corneal scars
• Cataract
• Vitreous bleeds
• Retinal tumours

Question 10

What are the advantages of a retinal reflection test?

Answer 10

Quick and non-invasive

Question 11

What are most red reflex abnormalities due to?

Answer 11

Cataracts

Question 12

What does a central dark opacity indicate on a retinal reflection test?

Answer 12

Cataract or corneal scar

Question 13

What does a white retinal reflection on aretinal reflection test indicate?

Answer 13

Retinoblastoma

Question 14

What are the 2 types of retinoblastoma?

Answer 14

• Familial - bilaterally (younger)

- Sporadically - unilaterally (older babies)

Question 15

WHy do retinal structures all move to the side at the fovea?

Answer 15

Make it thinner maximising acuety and photoreceptors are most tightly packed together to give highest acuity

Question 16

WHat does a pale neuro-retinal rim indicate?

Answer 16

Optic atrophy - toxcitity from drugs, poor diet, optic nerve being pressed on or optic neuritis

Question 17

What does a enlarged central cup and thinning of the neuro-retinal rim and enlarged cup to disk ration indicate?

Answer 17

Glaucoma

Question 18

What are new blood vessels growing on the optic disc associated with?

Answer 18

Proliferative Diabetic retinopathy

Question 19

What is an enlarged cup at the optic disk caused by?

Answer 19

• Glaucoma
• New retinal rim becomes thinned axons from ganglion cells are dying
• Associated with age ethnicity and intraoccular pressure

Question 20

What can raised intra-occcular pressure be associated with?

Answer 20

Glaucoma

- Can be reversed through eye-drops, laser and surgery

Question 21

What are the causes of swolen disc?

Answer 21

Pseudo swelling 
- Small discs 
- Calscium deposits 'Drusen'
Genuine Swelling 
- Optic neuritis (VA reduced)
- Raised ICP (VA normal): SOL, IIH, Hydrocephalus

Question 22

What is it called when a swollen disc is raised due to raised ICP?

Answer 22

Papilloedema

Question 23

What are the 3 key elements that should be commented on when examining the optic nerve head?

Answer 23

• Margin, colour, cup size

Question 24

What are the muscles of the eye?

Answer 24

• 6 extra-ocular muscles
• 2 horizontal recti (medial and lateral)
• 2 vertical recti (superior and inferior)
• 2 oblique (superior and inferior)

Question 25

What are the 3 types of cranial nerve palsy?

Answer 25

• 3rd CNP
• 4th CNP
• 6th CNP

Question 26

What is associated with 3rd CNP?

Answer 26

• Vertical diplopia
• Eye is ‘down and out’
• Diplopia every where
• Pupil dilated and ptosis
• Can be associated with an aneurysm - needs urgent brain imaging and angiogram

Question 27

What is associated with a 4th CNP?

Answer 27

• Oblique diplopia
• Head tilt away from side of the lesion
• Diplopia worse away from the side of the palsy if unilateral (adduction)
• Common after head injury
• Bilateral - might be congenital

Question 28

What is associated with a 6th CNP?

Answer 28

• Horizontal diplopia
• Worse in far distance
• Worse towards the side of the palsy if unilateral
• Bilateral - concerned that raised ICP is present

Question 29

What is the worldwide number 1 cause of blindness?

Answer 29

Cataracts

Question 30

In developed countries what is the main cause of blindness?

Answer 30

Macular degeneration

Question 31

WHat is the main cause of irreversible blindness in poor countries?

Answer 31

Glaucoma

Question 32

What is trachoma?

Answer 32

• Chlamydia

- Scarring of conjunctivqa which leads ro the eyelid turning into the cornea and causing corneal scarring