OD2 > OD week10 > Flashcards

OD week10 Flashcards

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1
Q

Paralytic (incomitant) strabismus – what is it?⭐

A

Type of strabismus where the angle of deviation varies with gaze direction.

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2
Q

Primary deviation – define it.

A

Deviation measured when unaffected eye fixates.

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3
Q

Secondary deviation – define it.⭐

A

Deviation measured when affected eye fixates → always larger.

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4
Q

Main causes of paralytic strabismus?⭐

A

Pathology or injury of brain, cranial nerves, neuromuscular junction, extraocular muscles, or orbit.

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5
Q

Optometrist’s key role?⭐

A

Recognise recent / urgent cases that may have life-threatening neurological causes.

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6
Q

Paralysis vs paresis vs palsy.

A

Paralysis: complete loss; paresis/palsy: partial weakness (used interchangeably).

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7
Q

Aetiology – congenital vs acquired.

A

Congenital: developmental defect; acquired: injury or disease of ocular-motor system.

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8
Q

Acquired causes – vascular?⭐

A

Diabetes, atherosclerosis, thyroid eye disease.

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9
Q

Acquired causes – trauma?⭐

A

Cranial or orbital trauma, fractures, birth trauma (forceps – VI nerve).

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10
Q

Acquired causes – inflammatory?

A

Cellulitis, sinusitis, cavernous-sinus thrombosis, syphilis, encephalitis.

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11
Q

Acquired causes – mass or tumour?⭐

A

Intracranial tumour, aneurysm, orbital or optic-nerve tumour.

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12
Q

Acquired causes – neuromuscular junction disease?⭐

A

Myasthenia gravis → fluctuating diplopia, worse as day progresses.

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13
Q

Main symptom of paralytic strabismus?⭐

A

Diplopia (usually recent-onset).

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14
Q

Four key history questions for diplopia.⭐

A

(1) Monocular / binocular? (2) Horizontal / vertical? (3) Worse in certain gaze? (4) Worse at distance / near?

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15
Q

Monocular diplopia – likely cause?

A

Ocular media cause → cataract, high astigmatism, corneal scar, keratoconus.

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16
Q

Binocular diplopia – cause category?⭐

A

Ocular misalignment from EOM, nerve, or brain disorder.

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17
Q

Horizontal diplopia suggests?⭐

A

Horizontal rectus muscle involvement (MR or LR).

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18
Q

Vertical diplopia suggests?⭐

A

Vertical recti or oblique muscle involvement.

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19
Q

Diplopia worse at distance indicates?⭐

A

Lateral-rectus (VI nerve) palsy.

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20
Q

Diplopia worse at near indicates?⭐

A

Medial-rectus (III) or superior-oblique (IV) palsy.

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21
Q

Tests for paralytic strabismus?⭐

A

Ocular motility, cover tests, Hess screen, Park’s 3-step test, external exam.

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22
Q

Primary vs secondary deviation on cover test.⭐

A

Secondary > primary when affected eye fixates.

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23
Q

Purpose of abnormal head posture?⭐

A

To minimise diplopia (align eyes in field with least deviation).

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24
Q

“Sit-up test” – purpose?

A

Differentiate ocular torticollis from orthopaedic neck cause.

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25
Park’s 3-step test – purpose?⭐
Diagnose cyclo-vertical / oblique muscle paresis (vertical diplopia).
26
Park’s 3-step test – Step 1.
Identify which eye is hypertropic in primary gaze.
27
Park’s 3-step test – Step 2.
Determine if hypertropia increases in right or left gaze.
28
Park’s 3-step test – Step 3.⭐
Determine if hypertropia increases on right or left head tilt (Bielschowsky).
29
Hess screen – what does it map?⭐
Extraocular muscle action field for each eye under dissociation.
30
Hess screen – interpretation rule.⭐
Smaller chart = paretic eye; larger chart = overacting yoke muscle.
31
3rd nerve (oculomotor) palsy – key signs?⭐
Ptosis, dilated fixed pupil, eye down & out (unopposed LR + SO).
32
3rd nerve palsy – urgent red flag?⭐
Acute painful onset = aneurysm → medical emergency.
33
3rd nerve palsy – pupil involvement patterns.⭐
Aneurysm/compression → pupil-involving; ischemic (DM) → pupil-sparing (but early aneurysm may spare).
34
3rd nerve palsy – management priority.⭐
Immediate neuro-imaging for all acute or partial cases.
35
4th nerve (trochlear) palsy – most common acquired cause?⭐
Trauma (congenital also common overall).
36
4th nerve palsy – diplopia pattern?⭐
Vertical/oblique diplopia, worse on down & in gaze, greater at near.
37
4th nerve palsy – typical posture?⭐
Head tilt to opposite side of lesion to minimise diplopia.
38
Bielschowsky head-tilt test – result in IV palsy.⭐
Hypertropia increases on head tilt to affected side.
39
6th nerve (abducens) palsy – function lost?⭐
Failure to abduct affected eye (lateral rectus weakness).
40
6th nerve palsy – symptom & posture?⭐
Horizontal diplopia, worse at distance; head turn to affected side.
41
6th nerve palsy – common causes?⭐
Raised ICP, vascular ischemia, tumour, base-of-skull fracture.
42
Duane’s syndrome – key features?⭐
Congenital limitation of abduction, globe retraction & palpebral fissure narrowing on adduction.
43
Duane’s syndrome – mechanism?⭐
Anomalous innervation of LR by 3rd nerve due to failed VI innervation.
44
Brown’s syndrome – mechanical problem?⭐
SO tendon / trochlear pulley restriction → limited elevation in adduction.
45
Brown’s syndrome – posture & mimic?⭐
Chin elevation & head tilt to affected side; mimics IO paresis.
46
Paretic sequelae – why does spread of comitance occur?
Adaptive over/under-actions develop to minimise diplopia over time.
47
Treatment of paralytic strabismus – first steps?⭐
Accurate refraction; manage diplopia with prisms or occlusion; refer for surgery if persistent.
48
Papilledema – what is it?⭐
Optic-disc swelling from raised intracranial pressure (ICP); nearly always bilateral.
49
Papilledema – mechanism?⭐
Raised ICP obstructs axoplasmic flow in the optic nerve → axonal swelling visible as disc oedema.
50
Papilledema – urgency?⭐
Immediate same-day neuro-imaging referral (consider intracranial mass until proven otherwise).
51
Papilledema – early vision?
Often normal visual acuity, colour vision, and pupils (early).
52
Papilledema – early symptoms?⭐
Transient visual obscurations (10–30 s veil/blur), photopsia, brief blindness.
53
Papilledema – systemic symptoms?⭐
Headache (morning, worse with Valsalva), nausea/vomiting, VI nerve palsy diplopia, pulsatile tinnitus.
54
Papilledema – early fundus signs?⭐
Mild hyperaemia, blurred nasal margins, swollen NFL, loss of SVP.
55
Papilledema – established fundus signs?⭐
Venous engorgement, tortuosity, obliterated cup, flame haemorrhages, cotton-wool spots, Paton’s folds, macular star.
56
Papilledema – chronic stage changes?⭐
Disc pallor, pseudo-drusen (“champagne cork”), optociliary shunt vessels.
57
Atrophic papilledema – appearance?
Pale grey discs, indistinct margins, few vessel crossings; severe VA loss.
58
Papilledema – common causes of raised ICP?⭐
Tumour/aneurysm/abscess/haemorrhage, hydrocephalus, meningitis, venous-sinus thrombosis, pseudotumor cerebri.
59
Idiopathic intracranial hypertension (IIH) – classic patient?⭐
Obese young woman with headache and papilledema; normal MRI/CSF composition.
60
IIH – related medications/vitamins?⭐
Vitamin A/retinoids, tetracyclines, steroids, NSAIDs, contraceptive pill, cyclosporine.
61
IIH – management?⭐
Weight loss; cease offending drug; medical/surgical measures to reduce ICP.
62
Malignant hypertension – disc effect?⭐
Optic-disc swelling with retinal haemorrhages, cotton-wool spots, hard exudates.
63
Diabetic papillopathy – description?⭐
Optic-disc swelling & hyperaemia in diabetics; VA mildly reduced or normal; may resolve spontaneously.
64
AION – relation to swollen discs?⭐
Can cause disc swelling; must urgently exclude GCA in arteritic cases.
65
Disc pseudo-swelling – key difference?⭐
No true axon swelling: vessels clear, no hyperaemia or haemorrhages, NFL reflexes normal.
66
Disc pseudo-swelling – causes?⭐
Small crowded disc (hyperopic), tilted disc, optic-nerve-head drusen.
67
Optic-nerve-head (ONH) drusen – what are they?⭐
Calcified hyaline deposits in ONH causing pseudo-swelling appearance.
68
ONH drusen – frequency?
Present in 1–2% of population; 75% bilateral.
69
ONH drusen – appearance?⭐
Elevated disc with scalloped margin; yellow refractile nodules; no hyperaemia; surface vessels visible; SVP present.
70
ONH drusen – imaging clue?⭐
Autofluorescence on FAF/cobalt blue/FA pre-dye; OCT shows ‘lumpy-bumpy’ subretinal hyporeflective spaces.
71
ONH drusen – complications?⭐
Field loss, AION, vessel occlusions, juxtapapillary neovascularisation.
72
ONH drusen – management?⭐
Educate; no treatment; annual visual fields to monitor.
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