2.4: The Eye and Systemic Disease

Question 1

Describe how you would identify the cause of an ophthalmology problem?

Answer 1

• History - Full medical and neurological exam - Blood tests - Imaging (MRI)

Question 2

Ocular motility defects can be caused by defects in…? (5 answers)

Answer 2

CN III CN IV CN VI Inter-nuclear Supra-Nuclear

Question 3

Describe CN VI palsy?

Answer 3

Most common cranial nerve palsy Cranial Nerve 6 - Abducens Causes abduction of the lateral rectus If palsy, eye is unable to abduct (remains staring straight ahead while the other eye abducts)

Question 4

Cause of CN VI palsy?

Answer 4

Microvascular (Micro-stroke) Raised intracranial pressure Tumour Congenital

Question 5

Describe how raised intracranial pressure cause CN VI palsy?

Answer 5

CN VI has to pass over the petrous tip of the temporal bone Raised ICP can press the nerve against the bone and cause palsy

Question 6

Describe CN IV palsy?

Answer 6

2nd most common cranial nerve palsy Cranial Nerve 4 = Trochlear Innervates superior oblique to cause abduction, elevation and intorsion In palsy, eye is unable to fully depress when in adduction

Question 7

Causes of CN IV palsy?

Answer 7

Most commonly congenital Then microvascular Tumour Trauma (if bilateral)

Question 8

If a patient presents with a BILATERAL CN IV palsy, what would you expect the cause to be?

Answer 8

Blunt Trauma to the head

Question 9

Patient presents with - Inability to full depress both eyes in abduction - Chin depressed - Extorsion of eyes

Answer 9

CN IV Palsy Due to blunt trauma to head

Question 10

Patient present with: - Headache - Sudden onset - Inability to abduct one eye?

Answer 10

CN VI Palsy Probably caused by raised ICP

Question 11

Describe CN III palsy?

Answer 11

Cranial nerve 3 = Oculomotor Innervates all other extra-ocular muscles Least common but important not to miss Eye looks DOWN and OUT Pupil may also be dilated in aneurysm

Question 12

Patient presents with: - Eye looking down - Eye abducted - Pupil dilated - Painful

Answer 12

CN III palsy Caused by aneurysm = EMERGENCY

Question 13

Causes of CN III palsy?

Answer 13

Microvascular (most common and benign) Aneurysm (Emergency) Tumour MS Congenital

Question 14

Difference between microvascular-caused CN III palsy and aneurysm causing CN III palsy?

Answer 14

• Aneurysm is painful - Aneurysm is an emergency - Aneurysm causes dilated pupils

Question 15

Look at this photo

Answer 15

Appreciate cranial nerves

Question 16

Describe briefly how the eyes work when you hear a noise to your left?

Answer 16

Eyes work together Both move to left Both move at same time and at same speed

Question 17

Describe internuclear ophthalmoplegia?

Answer 17

This is a disorder of gaze (where eyes move to same place at the same time) Caused by failure of adduction of one eye Causes horizontal diplopia (double vision)

Question 18

Most causes of Internuclear ophthalmoplegia?

Answer 18

Caused by dysfunction in the medial longitudinal fasciculus This can be caused by MS (young) or vascular (e.g.: Stroke in elderly)

Question 19

Describe the optic pathway?

Answer 19

Light hits retina Optic Nerve Optic Chiasma Optic Tract Optic Radiation Visual cortex of the occipital lobe

Question 20

Give some causes of visual field defects?

Answer 20

Vascular (Strokes) Space Occupying Lesions Demyelination (MS) Trauma (eg: Surgery)

Question 21

What causes damage to the optic nerve?

Answer 21

Ischaemic Optic Neuropathy (Damage due to lack of blood) Optic Neuritis - Inflammation of optic nerve (Caused by demyelination and inflammatory changes seen in MS) Tumours

Question 22

Describe the visual field defects from optic nerve?

Answer 22

Can affect entire field of vision Can affect just the superior/inferior parts If vascular cause, commonly just the top or bottom is affected and not both (altitude)

Question 23

Describe Optic Neuritis?

Answer 23

Inflammation of the optic nerve Often painful Progressive Loss of quality of vision (but most vision is still retained) Will get better over a period of months but some atrophy may have occurred

Question 24

What can affect the optic chiasma?

Answer 24

Pituitary Tumours (Common) Craniopharyngioma (Seen in children, Rare) Meningioma (Rare)

Question 25

Describe how visual loss is caused by optic chiasma pathology? What happens after treatment?

Answer 25

Compression causes visual field defects (Eg: Bitemporal hemianopia) After surgery, normal vision is restored

Question 26

Patient presents with: - Bitemporal Hemianopia?

Answer 26

Pituitary Tumour

Question 27

What can affect the optic tract and radiations?

Answer 27

Tumours Demyelination Vascular Abnormalities

Question 28

Describe the visual field disturbance from an optic tract/optic radiation pathology?

Answer 28

Homonymous defects No macula sparing Quadrantanopia (Quadrants affected)

Question 29

What can affect the visual cortex?

Answer 29

Vascular Disease (CVA) Demyelination

Question 30

Describe the visual field disturbance from a visual cortex pathology?

Answer 30

Homonymous Defect Macular Sparing

Question 31

When considering a differential, age is important

In someone over 50, most likely cause for ocular disease?

In someone in their 20s?

In someone aged 5 with a head tilt?

Answer 31

Vascular

MS (Demyelinating)

Congenital 4th Nerve Palsy