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Yr 3 - Core Conditions > Ophthalmology - Neurological Conditions > Flashcards

Ophthalmology - Neurological Conditions Flashcards

1
Q

What is mydriasis?

A

A dilated pupil

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2
Q

What is miosis?

A

A constricted pupil

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3
Q

Does raised intracranial pressure cause mydriasis or miosis?

A

Mydriasis (dilated)

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4
Q

Does Horner’s syndrome cause mydriasis or miosis?

A

Miosis

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5
Q

Do opiates cause mydriasis or miosis?

A

Miosis

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6
Q

Does trauma cause mydriasis or miosis?

A

Mydriasis

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7
Q

Do cluster headache cause miosis or mydriasis?

A

Miosis

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8
Q

Does CN III palsy cause miosis or mydriasis?

A

Mydriasis

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9
Q

What are the motor functions of CN III?

A
  • Levator palpebrae superioris
  • Extra-ocular muscles (except lateral rectus and superior oblique)
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10
Q

What is the parasympathetic function of CN III?

A

Sphincter pupillae muscles → causes constriction

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11
Q

What are the 2 types of CN III palsy?

A
  1. Surgical
  2. Medical
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12
Q

What is a surgical CN III palsy?

A

Refers to compressive lesions e.g. posterior communicating artery aneurysm

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13
Q

What is a medical CN III palsy?

A

Refer to non-compressive lesions e.g. multiple sclerosis, vascular causes such as diabetes or hypertension, vasculitis

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14
Q

Describe the presentation of the eye in CN III palsy

A
  • ‘Down and out pupil’
  • Ptosis
  • Double vision
  • Pupil dilation (in surgical CN III palsy)
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15
Q

Why does CN III palsy lead to a ‘down and out’ pupil?

A

Due to unopposed activation of lateral rectus and superior oblique

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16
Q

Why does CN III palsy lead to ptosis?

A

Due to impaired innervation to levator palpebrae superioris

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17
Q

Why does a ‘surgical’ CN III cause pupil dilation?

A

Due to parasympathetic (constrictive) fibres run on outside of nerve so external compression will impair function of these

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18
Q

Does a fixed pupil dilatation indicate a ‘surgical’ or ‘medial’ CN III palsy?

A

Surgical

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19
Q

What is the most common cause of a ‘surgical’ CN III palsy?

A

Posterior communicating artery aneurysm

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20
Q

What are some causes of a ‘medial’ CN III palsy?

A
  • Multiple sclerosis
  • Vascular causes e.g. diabetes, hypertension, vasculitis
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21
Q

What is the motor function of CN IV (trochlear)?

A

Superior oblique extra-ocular muscle → pulls eye down and inwards

22
Q

What is the presentation of CN IV palsy?

A
  • Double vision – worse in the vertical plane
  • Hypertropia (potentially) – this is a type of strabismus where either eye drifts/looks upwards
    • Eye points upwards and inwards
    • Patient may present with tilted head to compensate
23
Q

What are the 2 major causes of CN IV palsy

A
  • Ocular trauma
  • Diabetes mellitus
24
Q

What is the motor function of CN VI (abducens)?

A

Lateral rectus extra-ocular muscle → abducts eye horizontally away from midline

25
Q

In which plane is the double vision in CN VI palsy worse?

A

Horizontal plane

26
Q

In which plane is the double vision in CN IV palsy worse?

A

Vertical plane

27
Q

Presentation of CN VI palsy?

A

Double vision worse in horizontal plane

28
Q

CN VI palsy is known for being a ‘false localising sign’. What does this mean?

A

A false localising sign is a neurological sign that reflects dysfunction distant or remote from the expected anatomical locus of pathology.

CN VI palsy is known for being a ‘false localising sign’ due to path of the 6th nerve within the brain, making it easily compromised in a state of raised intracranial pressure.

29
Q

What are the causes of CN VI palsy?

A
  • Diabetic neuropathy
  • Stroke
  • Infection
  • Trauma
30
Q

What is Horner’s syndrome?

A

Damage to the sympathetic nervous system supplying the face

31
Q

What are the 4 main causes of Horner’s syndrome?

A
  • Pancoast tumour (apices of lungs)
  • Stroke
  • Carotid artery dissection (red flag = neck pain)
  • Multiple sclerosis
32
Q

Clinical features of Horner’s syndrome?

A
  • Triad of:
    • 1) Ptosis (drooping of upper eyelid)
    • 2) Miosis (pupil constriction)
    • 3) Anhidrosis (lack of sweating)
  • May have enophthalmos (sunken eye)
33
Q

Are light & accommodation reflexes affected in Horner’s syndrome?

A

No

34
Q

What is papilloedema?

A

Swelling of optic disc 2ary to raised intracranial pressure.

35
Q

Pathophysiology behind papilloedema?

A

The sheath around the optic nerve is connected with the subarachnoid space so CSF under high pressure can flow into the optic nerve sheath.

36
Q

What visual field defect will pre-chiasmal lesions result in.

A

ipsilateral monocular visual field defect.

37
Q

What visual field defect will post-chiasmal lesions result in.

A

homonymous visual field defects of the contralateral side.

38
Q

Describe the visual field defect in an optic nerve lesion

A

Ipsilateral monocular visual field defect

39
Q

Give some causes of an optic nerve lesion

A
  • Optic neuritis
  • Amaurosis fugax
  • Optic atrophy
  • Trauma
40
Q

Describe the visual field defect in an optic chiasm lesion

A

Bitemporal hemianopia

41
Q

What is the main cause of an optic chiasm lesion?

A

Pituitary adenoma e.g. prolactinoma

42
Q

Describe the visual field defect in an optic tract lesion

A

Contralateral homonymous hemianopia

43
Q

What are 2 main causes of an optic tract lesion?

A
  • MCA stroke
  • Tumour
44
Q

Describe the visual field defect in an optic radiation lesion

A

Homonymous contralateral quadrantanopia

45
Q

Describe the visual field defect in an optic radiation lesion affecting Meyer’s loop

A

Homonymous upper quadrantanopia (‘pie in the sky’)

46
Q

Which lobe is Meyer’s loop?

A

Temporal

47
Q

Describe the visual field defect in an optic radiation lesion affecting the parietal lobe?

A

Homonymous lower quadrantanopia (‘pie on the floor’)

48
Q

Describe the visual field defect in a lesion of the calcarine sulcus of the occipital lobe

A

Homonymous hemianopia with sparing of macula

49
Q

What are the 2 main cause of a calcarine sulcus of the occipital lobe lesion?

A
  • PCA stroke
  • Trauma
50
Q

What type of visual field defect would an MCA stroke cause?

A

Contralateral homonymous hemianopia

Yr 3 - Core Conditions (33 decks)

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