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DEP > strabismus and paediatrics > Flashcards

strabismus and paediatrics Flashcards

1
Q

which muscle has the closest and furthest insertion to the limbus and their distance

A

medial rectus closest 5.5

superior rectus furthest 7.7

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2
Q

movement of superior rectus

A

intorsion and adduction

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3
Q

movement of inferior rectus

A

depression

extorsion and adduction

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4
Q

movement of superior oblique

A

intorsion

abduction and depression

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5
Q

movement of inferior oblique

A

extorsion

abduction and elevation

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6
Q

what is hering’s law

A

yolk muscles involved in a particular direction of gaze receive equal and simultaneous flow of innervations.

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7
Q

sherrington’s law

A

increase in innervation of a muscle is accompanied by a decrease in innervation of its antagonist.

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8
Q

define ambylopia

A

characterized by a reduction in VA in the early years of life (<8 years of age) due to a developmental failure of the visual pathway between the eye and the visual cortex in the occipital lobe

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9
Q

aeitologies of ambylopia

A

Strabismus

refractive error

stimulus deprivation (e.g. cataract).

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10
Q

Mx of ambylopia

A

1) Treat underlying cause.
2) Occlusion therapy: The good eye is patched to allow visual connections between the amblyopic eye and the brain to develop properly.
3) Pharmacologic penalisation of the good eye using atropine. (Note: Atropine may cause photophobia and reverse amblyopia.)

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11
Q

characterisitcs of binocular single vision

A

simultaneous perception

fusion

stereopsis

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12
Q

define simultaneous perception

A

An image formed simultaneously on each retina.

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13
Q

define sensory fusion

A

ability to unite the two images from each retina to form a single image.

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14
Q

define motor fusion

A

The ability to align the eyes to maintain sensory fusion.

Motor fusion occurs via version (conjugate movements) and vergence (disconjugate movements) in order to achieve binocular vision.

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15
Q

define steropsis

A

perception of depth

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16
Q

tests for simultaneous perception and fusion

A

Worth 4-dot test, Bagolini glasses and synoptophore.

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17
Q

tests for motor fusion

A

Base-out or base-in prism bar or Risley prism tests. Applying a base-out prism moves the image to the temporal retina so the eye has to converge to achieve binocular single vision. The opposite is true for a base-in prism.

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18
Q

tests for stereopsis

A

Titmus, Lang, TNO, Frisby and synoptophore.

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19
Q

what is heterophoria

A

Deviation of the eye that is hidden by fusion and revealed when fusion is broken, for example, with an alternating cover test.

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20
Q

define esophoria

A

inward deviation of the eye

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21
Q

define exophoria

A

outward deviation of the eye

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22
Q

what is heterotropia

diagnosis

A

Abnormal alignment of the eye, also known as a manifest squint.

Can be tested using the cover test.

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23
Q

what is the normal accommodative convergence to accommodation

A

In the normal eye, one diopter of accommodation is accompanied by 3–5 PD of accommodative convergence.

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24
Q

the most common form of childhood squint

A

esotropia

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25
Q

possible causes of esotropia

A

nerve palsies, thyroid eye disease, trauma

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26
Q

what is fully accommodative esotropia

A

esotropia that resolves with correction of hypermetropia. Normal AC/A ratio.

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27
Q

Mx of fully accommodative esotropia

A

full cycloplegic hypermetropic correction

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28
Q

what is partially accommodative esotropia

A

partially resolves with correction of hypermetropia but needs treatment of ambylopia. Normal AC/A

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29
Q

Mx of partially accomoodative esotropia

A

fully cycloplegic hypermtropic correction and treatment of ambylopia

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30
Q

what is convergence excess esotropia

A

Esotropia for near vision only due to high convergence. High AC/A ratio.

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31
Q

Mx of convergence excess esotropia

A

bifocal glasses or surgery (e.g. bilateral MR recession).

32
Q

when does infantile esotropia develop

A

within the first 6 months of life

33
Q

what is infantile esotropia

A
  • Large-angle (>30PD) deviation
  • Cross-fixation (carries low risk of amblyopia)
  • Latent horizontal nystagmus

normally develops in first 6 months

34
Q

what is near versus distance esotropia

A

Distance: Esophoria for near vision and esotropia for distance

Near: Esotropia for near only but with normal AC/A ratio

35
Q

most common type of exotropia

A

intermittent exotropia

36
Q

Mx for intermittent exotropia

A

myopic correction, orthoptic exercises or surgery (e.g. unilateral or bilateral LR recession).

37
Q

what is distance exotropiia

classification

A

TRUE - exotropia made worse looking at a distance with normal AC/A ratio.

SIMULATED - there is a larger exotropia for distance with high AC/A ratio; however, the near exotropia is increased when looking through a +3D lens or after occlusion of the normal eye.

38
Q

what is near exotropia

A

Defined as a worse exotropia for near vision, it is common in young myopic adults or teenagers.

39
Q

what is constant exotropia

A

A constant large-angle exotropia, typically occurring within the first 6 months of life. It is usually associated with neurological anomalies

40
Q

Mx of constant exotropia

A

surgical with bilateral LR recession and MR resection.

41
Q

what is microtropia

A

A small angle squint <10PD (5°), most commonly an esotropia associated with anisometropia. Patients have subnormal binocular single vision with sensory and motor fusion and reduced stereopsis

42
Q

what is microtropia w identity

A

no manifest deviation on cover test but deviation can occur on 4PD test

43
Q

what is microtropia wo identity

A

manifest deviation on cover test

44
Q

what is duane retraction syndrome

A

innervation of the LR muscle by CN3 rather than CN6 with associated CN6 nucleus hypoplasia.

45
Q

characteristics of duane retraction syndrome

A

retraction of the globe on aDDuction. Associated with deafness or Goldenhar syndrome. Three types exist

I (most common) II
III
Esotropia with limited abduction
Exotropia with limited adduction
Esotropia with limited abduction and adduction
46
Q

what is brown syndrome and causes

A

This unilateral syndrome is caused by mechanical restriction of the SO tendon at the trochlea. It can be congenital or arise post-trauma/surgery

47
Q

characteristics of brown syndrome

A

limited elevation in adduction or on upgaze with an
- associated click sensation.

  • pts can’t look up and in
48
Q

what is resection

A

process of shortening the muscle (strengthening procedure).

49
Q

what is recession

A

process of loosening the muscle by moving it away from its insertion (weakening procedure).

50
Q

what surgery would be done in constant exotropia

A

bilateral LR recession (loosening) and MR resection (strengthening) corrects the eye misalignment.

51
Q

what is tucking procedure

A

augment the SO muscle. Indication is for congenital fourth nerve palsy.

52
Q

what is advancement procedure

A

bringing the muscle closer to the limbus. This is done to a previously recessed EOM.

53
Q

strengthening procedures

A

resection

tucking

advancement

54
Q

what is disinsertion

A

primarily used for a highly active Inferior Oblique. It separates the tendon at its insertion, making it weaker.

55
Q

innervation

primary function

secondary function superior rectus

A

CNIII

Elevation

intorsion & ADduction

56
Q

innervation

primary function

secondary function inferior rectus

A

CN3

depression

extorsion and ADDuction

57
Q

innervation

primary function

secondary function

superior oblique

A

CN6

intorsion

abduction & depression

58
Q

innervation

primary function

secondary function

inferior oblique

A

CN3

extorsion

ABduction & elevation

59
Q

antagonist-agonist muscles

A

muscles in same eye that move the eye in different directions

60
Q

synergist muscles

A

muscles in the same eye direction (right IR & right SO)

61
Q

Newborn baby VA test

A

fix and follow

62
Q

infants upto 3 years (pre verbal) VA test

A

Cardiff acuity test/ cardiff cards

63
Q

18m - 4 years (verbal) VA test

A

kay picture tests

64
Q

4-5 years test VA

A

Keeler crowded LogMAR test

65
Q

what is leucoria

A

white pupil - urgent referral to opthamology

66
Q

what is retinoblastoma

A

malignant tumour of the retina - most common intraocular tumor of childhood and most sinister cause

autosomal dominant (bilateral usually) or sporadic (usually unilateral)

loss of function of retinoblastoma tumour suppressor gene on chromosome 13

Mx
- radioactive plaque or enucleation + adjuvant chemo

67
Q

what is congenital cataract

features

Mx

A

leukocoria, dull red reflex, squint or nystagmus

commonly idiopathic but alos hereditary linked w rubella

Mx
surgery - lensectomy
— contact lens, aphakic glasses or lens implant

68
Q

what is retinopathy of prematurity

A

screen pre term babies (<30 weeks) + low birth weight (<1.5Kg)

retinal periphery is only fully vascularised close to term

incomplete retinal vascularisation causes hypoxia

leukocoria seen in advanced cases due to a retinal detachment

Mx- ablation of avascular retina + laser

69
Q

what is coloboma

A
  • keyhole pupil
  • present at birth
  • failure of choroidal fissure to close during embryological development - mutation of PAX2 gene + also linked with fetal alcohol syndrome
  • degree of visual impairment ranges from asymptomatic to significant visual loss
  • white retinal reflex + severe amblyopia
70
Q

what is ptosis

Mx

A
  • more likely t have weak LPS
  • more pronounced when tired or unwell

Mx

  • require urgent frontalis suspension surgery (within 2-4 weeks)
  • take part of fascia lata and insert it onto tarsal plate and frontalise muscle
71
Q

what is congenital glaucoma/ buphthalmos

A

buphthalmos is an enlargement of the eye acd in children is a feature of the congenital glaucoma

  • consanguity
  • corneal diameter >12mm before 1 year
  • cloudy cornea
  • excessive tearing
  • photophobia

mX

  • > Medical: drops
  • > surgical: goniotomy
72
Q

Pathogens of chlamydial conjunctivitis

Sx

Ix

Mx

A

chlamydia trachomatis

unilateral red eye
white follicules
periauricular lympahdenopathy
mucopurulent/’stringy’ discharge

Ix - giemsa stain

Mx
erythromycin drops

73
Q

Pathogens

Sx

Ix

Mx

A

Gram -ve diplococci Neiserriae Gonnorhoea

  • severe infection can cause corneal ulceration and perforation
  • severe discharge
  • early presentation
  • may co-exist with chlamydia

Ix - swab gram stain

Mx
- IM/IV ceftriaxone

74
Q

what is capillary haemangioma

A

swelling commonly superonasally from borth which increases in size for 6 months

  • benign tumour
  • risk of refractive error
  • can causes mechanical ptosis which risks ambylopia if the lid covers the visual acis

Mx - oral beta blockers

75
Q

what is limbal dermoid

A

benign congenital tumour often ass w eyelid coloboma or goldenhar’s syndrome

76
Q

what is dermoid cyst

A

smooth round non-tneder immobile lump on orbital rim

- gradually grows with risk of rupture

DEP (20 decks)

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