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Year 4 Ophthalmology > Strabismus > Flashcards

Strabismus Flashcards

1
Q

Role of orthoptics

A
  1. Visual development in children and amblyopia
  2. Identification and mx of strabismus before surgery
  3. Eye movement disorders
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2
Q

Amblyopia

A

Lazy eye - reduced visual acuity in the absence of any structural cause or ocular disease

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3
Q

How to test visual acuity

A

Snellen chart

logMAR chart

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4
Q

How to perform a Snellen test

A
  1. Ask patients if they wear glasses or contact lenses
  2. Stand 6 metres or 3 metres using a mirror
  3. Cover one eye and read lines
  4. If can’t read, use pin point
  5. If still can’t read, move forward
  6. If still can’t read, use fingers
  7. If still can’t read, use hand movements
  8. If still can’t read, use light
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5
Q

How to interpret a Snellen chart

A

6/6 +2

  • Numerator = distance from board
  • Denominator = line they can read
  • Indices = extra letters they can read

6/6 means they can see what the average population sees at 6 metres

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6
Q

Snellen chart and logMAR comparison

A 
6/60 = 1.0
6/12 = 0.3
6/6 = 0.0
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7
Q

LogMAR advantages

A

Decrease size in a standard format

Same number of letters on each row

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8
Q

Minimum visual acuity for driving

A

6/12

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9
Q

How to assess visual acuity in babies and young children

A

Keeler preferential looking cards - 8 weeks - 12 months

Cardiff acuity cards

Kay pictures

LogMAR Keeler book

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10
Q

Purpose of the cover test

A

Detect the presence of a manifest or latent deviation

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11
Q

Latent deviation

A

Squint that is not obvious unless an alternate cover test is done

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12
Q

Manifest deviation

A

Can see quint just by observing and using a cover uncover test

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13
Q

Associated signs with strabismus

A

Head tilting (away from lesion)
Ptosis
Nystagmus
Unequal pupils - when shining light (corneal reflections)

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14
Q

Esotropia

A

Inwards strabismus

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15
Q

Exotropia

A

Outward strabismus

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16
Q

Hypertropia

A

Upwards strabismus

17
Q

Hypotropia

A

Downwards strabismus

18
Q

Strabismus mimics

A

Horners syndrome

Physiological eye folds

19
Q

How to carry out a cover test

A
  1. Corneral reflection symmetry using a pen torch
  2. Hold target at eye level, cover one eye and reveal
  3. Swap eye
  4. Test with and without glasses
20
Q

Why does amblyopia occur

A

Cortical adaptation due to abnormal binocular environment e.g.

  • strabismus
  • anisometropia
  • high refractive bilateral error
  • stimulus deprivation - ptosis
  • high astigmatism
21
Q

Anisometropia

A

Interocular difference in refractive error - using one eye more than the other

22
Q

Concomitant strabismus

A

Strabismus is the same regardless of where the patient is looking

23
Q

Causes of concomitant strabismus

A

Children:

  • Refractive error
  • FHx
  • Prematurity
  • Developmental delay
  • idiopathic
24
Q

orthoptic assessment

A

Visual acuity - Snellen/logMAR
Cover test
Ocular movement test (H test)

25
Q

Investigations for strabismus

A

Orthoptic assessment
Cycloplegic refraction
Fundoscopy
Slit lamp

26
Q

Cycloplegic refraction

A

Paralyse lens to prevent compensatory accommodation reflex

27
Q

Red flag signs for strabismus

A

Severe headache
Dizziness
Nause and vomiting

28
Q

Amblyopia and strabismus management

A
  1. Glasses for refractive adaptation
  2. If visual acuity not equal, use patch at 4 - 5 yo to improve vision in weaker eye
  3. Once vision is equal and squint still apparent, surgery suggested
29
Q

Incomitant strabismus

A

Different with different areas of gaze

30
Q

Causes of incomitant strabismus

A

Cranial nerve palsies
Thyroid eye disease
Myasthenia gravis
Trauma/ orbital mass

31
Q

Types of diplopia

A

Monocular

Horizontal binocular diplopia
Vertical binocular diplopia
Oblique binocular diplopia

32
Q

How to test for monocular vision

A

Whilst covering one eye, diplopia persists

33
Q

Causes of monocular vision

A

Cataracts

Uncorrected refractory error

34
Q

How to test for binocular vision

A

Whilst covering one eye, the diplopia goes away

35
Q

Driving with diplopia

A

Should not drive

36
Q

Why do people with childhood strabismus not have diplopia

A

Retinal suppression

Year 4 Ophthalmology (27 decks)

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