Ophthalmoscopy and Visual Fields

Question 1

What are the 4 parts of the optic nerve?

Answer 1

Intraocular
Intraorbital
Intracanalicular
Intracranial

Question 2

Where in the skull is the optic canal located?

Answer 2

The greater wing of the sphenoid bone

Question 3

What is the optic nerve also known as?

Answer 3

CN II

Question 4

What are the three things to pay attention to when describing the optic nerve when doing an ophthalmoscopy?

Answer 4

Contour (borders of the disc)
Colour
Cup (bright centre of disc)

Question 5

Describe the normal appearance of the optic nerve?

Answer 5

Clear and well defined borders
Orange-pink colour with a pale centre
Cup to disc ratio should be roughly 0.3

Question 6

What conditions can cause abnormal contours of the optic nerve?

Answer 6

Disc swelling (e.g. papilloedema)
Optic disc drusen

Question 7

What conditions can cause an abnormal colour of the optic nerve?

Answer 7

Advanced glaucoma
Optic neuritis
Ischaemic optic neuropathy
Compressive lesion

Question 8

What condition can cause a large cup?

Answer 8

Glaucoma

Question 9

Which are darker on fundoscopy, veins or arteries?

Answer 9

Veins

Question 10

What is the cup?

Answer 10

The centre of the optic disc that is devoid of neuroretinal tissue

Question 11

What is the most common cause of a unilateral swollen disc?

Answer 11

Vascular - e.g. infarcion

Question 12

What are causes of a swollen disc?

Answer 12

Papilloedema

Disc drusen

Question 13

What is papilloedema?

Answer 13

A swollen nerve in the context of raised ICP

Question 14

What is disc drusen?

Answer 14

Swollen disc due to a collection of material in the optic nerve

Question 15

What are the causes of a pale disc?

Answer 15

Compromised circulation
Demyelination
Drugs (e.g. ethambutol)
Nutritional problems (e.g. B12, folate)

Question 16

What does myelinated nerve fibres look like?

Answer 16

Bright white area going out from the nerve

Question 17

What are the clinical features of myelinated nerve fibres?

Answer 17

Changes on visual field test

Enlarged blind spot

Question 18

What is a homonymous visual field defect?

Answer 18

One affecting the same part of field in each eye (e.g. left field of vision in both eyes)

Question 19

What is an incongruous visual field defect?

Answer 19

One affecting different parts of the field in each eye (e.g.upper left in right eye and upper and lower left in the left eye)

Question 20

What is a hemianopic visual field defect?

Answer 20

One that affects half of the visual field

Question 21

What is a quadrantanopic visual field defect?

Answer 21

One that affects a quarter of the visual field

Question 22

Where would a defect be if the whole visual field of the right eye is affected?

Answer 22

Right optic nerve, pre-chiasmal

Question 23

Where would a defect be if the whole visual field of the right eye and the peripheral part of the upper temporal left visual field is affected?

Answer 23

Sometimes the crossing nasal fibre does a small loop into the contralateral optic nerve - defect there

Question 24

Where would a defect be if the patient has a bitemporal hemianopia?

Answer 24

Optic chiasm

Question 25

Where would a defect be if the patient has a left homonymous hemianopia?

Answer 25

At any point beyond the chasm on the right hand side of the brain

Question 26

Where would a defect be if the patient has a left homonymous quadrantanopia?

Answer 26

Nerve fibres going from the chiasm to the visual cortex fan out - so one affecting only some of the fibres

Question 27

Where would a defect be if the patient has a left homonymous hemianopia that spares central vision?

Answer 27

Defect that spares the macula due to circulation in the occipital cortex