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Binocular vision YR 3 > Investigation of concomitant esotropia > Flashcards

Investigation of concomitant esotropia Flashcards

1
Q

what are the 3 classifications of esotropia

A
  • primary esotropia
  • secondary esotropia
  • consecutive esotropia
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2
Q

what is a primary esotropia

A

its an initial esotropia i.e. the first thing they have had

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3
Q

what is a secondary esotropia

A

it is a result of something else e.g. poor vision in the deviating eye from a cataracts or corneal opacity whereby the px developed a secondary squint as a result of this

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4
Q

what is a consecutive esotropia

A

it is the result from a surgery that was done to correct an exotropia whereby the deviation has now gone the opposite way, so the patient developed an esotropia as a result

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5
Q

What are the 2 types of primary constant esotropias?

A
  • accommodative

- non-accommodative

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6
Q

what are the 2 types of primary esotropias

A
  • intermittent

- constant

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7
Q

what are the 2 types of primary accommodative intermittent esotropias

A
  • fully accommodative esotropia

- convergence excess esotropia

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8
Q

what causes the deviation of a primary accommodative esotropia to increase

A

the more accommodation and the more they focus

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9
Q

what is seen with a primary intermittent accommodative esotropia

A

the esotropia can be for near or for distance, it can be there without the glasses, but with the glasses on their is no esotropia present

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10
Q

what type of primary accommodative constant esotropia is there and what does it mean

A
  • esotropia with an accommodative element

the esotropia is there all the time with all viewing distances when the patient is not wearing their glasses

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11
Q

what are the 2 types of primary non-accommodative esotropias

A
  • intermittent

- constant

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12
Q

what are the 3 types of primary non-accommodative intermittent esotropias

A
  • near esotropia
  • distance esotropia
  • cyclic esotropia
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13
Q

what are the 2 types of primary non-accommodative constant esotropias

A
  • early onset esotropia

- acute late onset esotropia

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14
Q

what are the 6 possible aetiologies of an esotropia

A

Various factors contribute in varying degrees:

  • Hereditary (family history)
  • Refractive errors
  • Neurological defects (higher incidence of getting esot)
  • Innervational causes
  • Anatomical/mechanical factors
  • Febrile illness (higher incidence of getting esot)
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15
Q

a hereditary cause of esotropia often _________ more than _____ member of a ________

A

a hereditary cause of esotropia often affects more than one member of a family

i.e. if more than one family member has esotropia then that person is more likely to develop an esotropia

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16
Q

what is the mode of inheritance of an esotropia and which gene locus is responsible for some types of squint

A
  • Mode of inheritance unclear – multi-factorialthe trait is produced by a number of pairs of genes that have an additive effect
  • The gene locus has been identified in certain specific types of squint e.g. CFEOM
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17
Q

_________ discovered the close relationship between _____________ and ____________

A

Donders discovered the close relationship between accommodation and convergence

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18
Q

what is required to give a clear retinal image with an uncorrected hypermetropia and therefore what must all patients have when investigating an esotropia

A
  • an excessive amount of accommodation

- all patients must have a cyclopegic refraction

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19
Q

accommodation and refraction: If motor fusion is _____________ the eyes may _________ _________

A

If motor fusion is inadequate the eyes may deviate inwards

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20
Q

what is a major risk of developing a strabismus

A

refractive errors

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21
Q

what are not all esotropias in origin

A

accommodative (some are non-accommodative)

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22
Q

what does the amount of deviation induced by accommodation depend on

A

the individual’s AC/A ratio

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23
Q

accommodation and refraction: what is a high AC/A ratio found in

A

in cases of low rather than moderate hypermetropia and people with convergence excess esotropia

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24
Q

which types of esotropia does uncorrected refractive error most commonly lead to

A

several types of strabismus most commonly accommodative with moderate degree of hypermetropia

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25
Q

what 2 things does anisometropia lead to

A

central suppression and amblyopia

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26
Q

High incidence of strabismus in ______ __________ children

A

High incidence of strabismus in brain damaged children

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27
Q

Neurological defects: in which type of brain damage is a child with an esotropia more common in

A

Children with cerebral palsy

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28
Q

Neurological defects: what is an esotropia more prevalent than in a child with brain damage and by how much

A

3x more prevalent than exo

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29
Q

Neurological defects: what can cause a child to have brain damage and subsequent esotropia

A

Premature/low birth weight babies

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30
Q

what are the 2 possible causes of innervational factors in an infantile esotropia

A

caused by:
- congenital defect in neural wiring of the brainstem

or a

  • maldevelopment of visual cortex as find OKN abnormal/absent when stimulus moved temporally
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31
Q

what is an innvervational cause of a non-accommodative esotropia

A

Paralytic in origin:

- Paresis of an EOM becomes concomitant with time

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32
Q

Anatomical/mechanical factors: what causes a concomitant deviation and more likely to be incomitant

A

Congenital absence or anomalous insertion of an EOM

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33
Q

Strabismus is commonly seen in cases of ____________ abnormalities

A

Strabismus is commonly seen in cases of craniofacial abnormalities

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34
Q

what are A and V patterns seen in

A

anomalies of the lid fissures

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35
Q

anatomical/mechanical factors cause ___________ rather than ___________ esotropia

A

anatomical/mechanical factors cause incomitant rather than concomitant esotropia

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36
Q

what is a concomitant esotropia

A

the degree of deviation is primary position stays the same in all directions of gaze

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37
Q

which sort of febrile illnesses is linked to a concomitant esotropia and under which age and rather than cause it what does it do

A
  • measles and chicken pox
  • under 6 years of age
  • rather than causing the concomitant esotropia, it participates in it
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38
Q

what are the 5 aims of investigation

A
  • Diagnose presence and type of strabismus they have in primary position
  • Determine if BSV is present all or some of the time
  • Elicit whether patient with constant strabismus has capacity to fuse images to restore BSV
  • Area and density of suppression
  • Measure angle of deviation that they have in primary deviation
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39
Q

what 4 things will you carry out in order to investigate the concomitant esotropia

A
  • A clear case history will give an indication of the type of esotropia present
  • Full orthoptic investigation
  • Cycloplegic Refraction
  • Fundus and media examination by an ophthalmologist to exclude any pathology
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40
Q

why do you want to carry out a clear history when investigating the esotropia

A

it will give an indication of the type of esotropia present

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41
Q

why do you want to carry out a fundus and media examination and by who when investigating the esotropia

A
  • to exclude any pathology

- by an ophthalmologist

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42
Q

list some types of questions you will ask in your history in order to determine the type of esotropia a patient has

A
  • how long have they had the squint for?
  • is it there all the time or only some of the time?
  • is it one eye or alternating?
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43
Q

what 2 things can you do whilst carrying out your full orthophoric investigation

A
  • look at the angle of deviation
    and
  • density of suppression
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44
Q

what can be the 2 other causes of an esotropia if there was nil pathology after carrying out the fundus examination

A
  • amblyopia

- reduced va

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45
Q

which drug will you use in your cylopegic refraction for a 6/12 year old px to investigate their esotropia

A

1% cylclopentolate

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46
Q

which drug will you use in your cylopegic refraction for a less than 6 month old px to investigate their esotropia

A

0.5% cyclopentolate

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47
Q

which drug will you use in your cylopegic refraction for a px with darkly pigmented irides

A

atropine 1%

the only thing you need to deduct is your working distance, so give them the full rx that they need

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48
Q

what is prescribed to a patient and for how long to enable a accurate diagnosis of a patient’s esotropia from refraction

A

glasses worn full time for 1 month

this can suggest if a patient’s esotropia is constant or intermittent, accommodative or non-accommodative to begin with

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49
Q

what is a intermittent fully accommodative esotropia always associated with

A

hypermetropia usually of a moderate amount +3.00DS to +6.00DS

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50
Q

what does a cover test with glasses reveal in a intermittent fully accommodative esotropia

A

well compensated esophoria for all distances when wearing their full hypermetropic correction

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51
Q

what does a cover test without glasses reveal in a intermittent fully accommodative esotropia and why

A

esotropia (unilateral or alternating) of variable size depending on amount of accommodation exerted

the patient will start to accommodate more and will have a constant esotropia for near and distance

52
Q

what is a intermittent accommodative convergence excess esotropia usually, occasionally and rarely associated with

A
  • usually hypermetropia
  • occasionally with emmetropia
  • rarely with myopia
53
Q

what does a cover test with glasses reveal in intermittent accommodative convergence excess esotropia

A
  • Near to light straight with BSV
  • Near to target Esotropia on accommodation
  • Distance esophoria with BSV
54
Q

what does a cover test without glasses reveal in intermittent accommodative convergence excess esotropia

A

constant esotropia at distance and near

55
Q

what is the aetiology of a intermittent accommodative convergence excess esotropia

A

a high AC/A ratio due to their over accommodation at near

56
Q

what can a constant esotropia occur with or without

A

without an accommodative element

57
Q

what does a constant esotropia with an accommodative element mean

A

the patient is hypermetropic

58
Q

what will a patient with a constant unilateral esotropia have and what can this depend on

A
  • slight to dense amblyopic
  • the amount of amblyopia will depend on how long the squint has been present, if it is picked up earlier, the degree of the squint is only slight
59
Q

what is equal in a alternating constant intermittent esotropia

A

equal va in between both eyes

60
Q

The deviation will __________ in size with glasses in __________ with an _____________ element

A

The deviation will reduce in size with glasses in esotropia with an accommodative element

61
Q

what are the 3 types of intermittent esotropia

A
  • Near
  • Distance
  • Cyclic
62
Q

what is a non-accommodative intermittent esotropia less common than

A

than an intermittent accommodative esotropia

63
Q

when can an esotropia occur with a non-accommodative intermittent esotropia

A 
- at distance only 
or 
- at near only 
or 
- intermittently at both distances
64
Q

what is a near esotropia (esotropia at near fixation) not explained by

A

a high AC/A ratio

65
Q

what will a patient with a intermittent non-accommodative near esotropia have at distance fixation

A

orthophoric/esophoria with BSV

66
Q

a patient with a intermittent non-accommodative near esotropia have equal _________ __________

A

a patient with a intermittent non-accommodative near esotropia have equal visual acuity

67
Q

a patient with a intermittent non-accommodative near esotropia will have no significant __________ _________

A

a patient with a intermittent non-accommodative near esotropia will have no significant refractive error

68
Q

what will a patient with a intermittent non-accommodative distance esotropia have at near fixation

A

orthophoric/esophoria with BSV

69
Q

what may a patient with a intermittent non-accommodative distance esotropia be associated with

A

myopia

70
Q

what is a cyclic esotropia also known as and why

A
  • alternate day squint
  • because it follows a 24 hour cycle, one day there is an esotropia with no binocular function and the next day they are straight an binocular
  • on the squinting day, the patient will have no diplopia because they will be surpassing
71
Q

what are the 2 types of non-accommodative constant esotropias

A
  • Infantile Esotropia

- Acute late onset Esotropia

72
Q

what is the age of onset of a non-accommodative constant infantile esotropia

A

is within the first 6/12 months of birth

73
Q

what is the most likely cause of a non-accommodative constant infantile esotropia

A

by maldevelopment of cerebral visual motor pathways

74
Q

what did a recent study in holland show about a non-accommodative constant infantile esotropia

A

showed a delay in motor and mental development in infants with this type of esotropia

75
Q

in how many % of children with neurological and developmental problems does a non-accommodative constant infantile esotropia occur

A

30%

76
Q

how rare is a non-accommodative constant infantile esotropia in the esotropia/strabismus population

A

0.27% out of the 2-3% off all esotropias

77
Q

infantile esotropia does not have a significant ______________ component but it is important to correct any significant _________ _________

A

infantile esotropia does not have a significant accommodative component but it is important to correct any significant refractive error

78
Q

how to both eyes appear to be in an infantile esotropia

A

with a large and obvious esotropic appearance

79
Q

explain how a baby with infantile esotropia will look at an object and how they will place their head and what is this called

A
  • Baby fixes with one eye and face turns to the same side i.e. Left constant squint and face turn to Right
  • Then swaps fixation and Right constant squint/esotropia with face turn Left as the left eye will not attempt to look towards the left gaze at all because the R eye will be looking in that direction
  • Called “cross fixation”
80
Q

what is the incidence of amblyopia with infantile esotropia and why

A

low (15%-19%)

because of the alternating nature of the squint

81
Q

what gets broken if a baby with infantile esotropia undergoes surgery

A

their alternating squint

82
Q

what can occur post operatively in a baby who has infantile esotropia and what can be done to avoid this

A
  • residual eso deviation becomes unilateral with the likely development of strabismic amblyopia as the baby won’t have the ability to alternate their squint
  • must reverse the amblyopia with occlusion treatment
83
Q

as well as broken alternating squint and hence possibility of amblyopia, what are other associated features and what occurs in infantile esotropia

A
  • Dissociated vertical deviations (DVD)
    Spontaneous turning up of each eye individually when daydreaming, fatigued or when each eye individually is covered – often asymmetric
    This drifting up is best seen using a semi-opaque occluder (Spielmann) as the eye can be observed through the occluder
    When the cover is removed the elevated eye drifts downwards and settles in the pp
  • Ocular movements
  • Manifest latent nystagmus (MLN)
84
Q

when is Dissociated vertical deviations (DVD) least likely to present and when may it develop from

A
  • DVD infrequently presents before the age of 2 years

- May develop after satisfactory horizontal surgery to reduce the eso deviation

85
Q

what causes the amount of elevation of Dissociated vertical deviations (DVD) to increase and as a consequence what does this make it difficult to measure

A
  • increase on prolonged occlusion

- very difficult to measure the vertical movement with any degree of accuracy

86
Q

with Dissociated vertical deviations (DVD), what also occurs when the eye elevates and what occurs when the eye depresses, also what makes it easier to observe this

A
  • As the eye elevates it frequently also extorts and then intorts as it depresses
  • This is more easily observed by watching a fleck in the iris or a conjunctival vessel
87
Q

explain what ocular movements is seen with infantile esotropia

A

Often see inferior oblique (IO) overreactions (full eye abductions of each eye)
The eye nearer the nose on horizontal gaze tends to updrift
Overaction is also seen on contralateral elevation i.e. where the IO has its maximum elevating action
Abduction of either eye is normally full, though abduction can be difficult to assess in babies

88
Q

explain how you will assess that abduction is full in a child with infantile esotropia

A

to cover one eye and take the other uncovered eye out as far as you can

if you were to test their ocular movements with both eyes open, because of their cross fixation = you won’t be able to pick up where their abduction is full

89
Q

explain the manifest latent nystagmus which occurs with infantile esotropia and what is the outcome of their OKN

A

Horizontal small amplitude nystagmus which increases on dissociation (i.e. as soon as you occlude one eye)
Jerk nystagmus with the fast phase towards the unoccluded eye
May not be possible to see the manifest component clinically with both eyes open but noticeable as soon as you cover one eye individually
Abnormal OKN – absent or weak response from nasal to temporal movement (normal temporal to nasal)

90
Q

when does the manifest latent nystagmus found with infantile esotropia tend to increase and hence when does vision tend to improve and how will you check this

A
  • The nystagmus often increases in abduction and decreases or is even absent in adduction
  • Vision therefore improves if the eye is adducted
  • Patients often turn their face to put the eye in adduction (towards the nose) to achieve the best VA
  • Alternate this face turn when testing VA and do it monocularly
91
Q

which 2 tests will you carry out on a child with infantile esotropia

A
  • cover test
    and
  • assessment of binocular function
92
Q

what is observed in a cover test on a child with infantile esotropia

A
  • Eso deviation likely to be alternating with the baby adopting a face turn to either side depending on which eye is fixing
  • In older children, especially if they have had surgery to reduce the squint more likely to have a unilateral eso deviation – RCS or LCS (a constant eso and lose ability to alternate)
  • Often see a small vertical deviation as well as the eso as a result of a large inferior oblique action
  • Look for DVD, extorsion and MLN
  • Use a Spielmann occluder (to pick up their DVD)
  • These features are not seen until the child is older possible due to co-operation
  • May only occur after surgery
93
Q

what may you find from an assessment of binocular function from a child with infantile esotropia

A
  • Very unlikely to have any BV due to the maldevelopment of cerebral visual motor pathways
  • As the onset of eso deviation is either at birth or within the first few months of life the binocular reflexes have not developed
  • Find suppression responses on BV tests (suppress with they eye they are squinting)
94
Q

what is a acute late onset esotropia, what are the symptoms and which age group does it occur in

A
  • Constant esotropia (may have initially been intermittent) with a large angle and no accommodative element
  • Usually complain of diplopia or seen to close one eye
  • develops between age 4-5 years old
95
Q

what is normal and present with acute late onset esotropia

A
  • Normal retinal correspondence and sensory and motor fusion present
  • Full range of eye movements
96
Q

list all the age onsets of all 4 esotropias that occur in childhood

A
  • Within 6/12 of birth – infantile esotropia
  • 6 months to 2 years – constant esotropia
  • After 2 years – intermittent accommodative esotropia
  • Unusual after 4/5 years – late onset
97
Q

list 17 investigations that can be done for all types of esotropias

A
  • case history
  • mode of onset
  • duration of squint
  • previous treatment
  • general health
  • family history
  • birth history
  • vision
  • cover test
  • ocular movements
  • measurement of deviations
  • controlled binocular acuity
  • assessment of AC/A ratio
  • assessment of binocular functions (on an intermittent eso and differently on a constant eso)
  • symptoms
  • post diplopia test
  • botulinum toxin
98
Q

what 5 possible questions will you ask in case history when investigating an esotropia

A 
Ask specific questions related to squint seen at home:
Which eye?
Direction of squint?
How often
When do they notice it
How long has it been there for?
99
Q

what does asking ‘which eye’ the squint is seen in case history of investigating esotropias tell you

A

whether its a constant squint or only present in one eye, or if it alternates between each eye

100
Q

what does asking ‘how often’ the squint is seen in case history of investigating esotropias tell you

A

was it there intermittently initially and now constant? or only there every other day

101
Q

what does asking ‘when do they notice it’ about the squint in case history of investigating esotropias tell you

A

it is likely to be accommodative if over the age of 2, they will say they can notice the squint more when they’re focussing e.g. reading or watching tv etc

102
Q

what does asking about the mode of onset when investigating esotropias tell you

A
  • Parents may notice the eso deviation only intermittently e.g. when looking/focussing on a near target
  • May have been intermittent in the past and now constant or always constant from onset
  • Rarely a cyclic esotropia – eso present on alternate days (24h cycle)
103
Q

what does asking about the ‘duration of the squint’ when investigating esotropias tell you

A
  • The length of time a squint has been present will indicate whether there is the:
    a) presence of amblyopia (so check vision of squinting eye before straight eye)
    b) constant squint, suppression and loss of binocular vision
  • The longer the squint has been present the more likely the above will have developed
104
Q

what does asking about ‘previous treatment’ if an older child has had treatment elsewhere when investigating esotropias tell you

A
  • Any treatment for other ocular pathology e.g. unilateral congenital cataract leads to secondary esotropia
  • Previous surgery for an intermittent or constant exotropia resulting in a consecutive esotropia
  • if they have been prescribed Glasses, occlusion, surgery and its effect on the esotropia
105
Q

what does asking about ‘general health’ when investigating esotropias tell you

A
  • Likely to be good
  • A febrile illness e.g. measles may be an attributable cause
  • Higher incidence of squints in children with developmental disorders e.g. cerebral palsy
106
Q

what does asking about ‘family history’ when investigating esotropias tell you

A
  • No specific inheritance pattern in strabismus
  • Often several members of one family are affected – research into inheritance patterns and role of genetics
  • May be a family history of refractive error
107
Q

what does asking about ‘birth history’ when investigating esotropias tell you

A
  • Squints more common in premature infants
  • Any birth trauma?
  • forceps or normal delivery?
108
Q

how will you test vision when investigating an esotropia, and what type of visions is revealed with an intermittent, constant and secondary esotropia

A
  • Test vision:
    Uniocularly (allow patient to face turn to achieve best VA)
    BEO when needed (as likely to be better than uniocular as the nystagmus is reduced/absent when both eyes are open) so test both mono and BEO
    Near and distance
  • Intermittent esotropias should have good and equal vision
  • Constant esotropias are more likely to have strabismic amblyopia depending on how long it is present
  • VA is likely to be very poor in the deviating eye in secondary esotropia
109
Q

how will you perform a cover test and what is a cover test good for diagnosing, when investigating an esotropia

A
  • Performed with and without glasses (if worn)
  • Important to use a light and an accommodative target at near (see CBA)
  • Look for DVD, extorsion and MLN (Use a Spielmann occluder) in those with infantile esotropia
  • May only occur after surgery
  • PRIME TEST for diagnosing the type of esotropia present
110
Q

what does performing a cover test with and without glasses tell you when investigating an esotropia

A

it tells you of the diagnosis of what esotropia they do have

111
Q

why is it important to use a light and an accommodative target at near when performing a cover test to investigate an esotropia

A

it helps you to differentially diagnose between accommodative and non-accommodative esotropia

112
Q

how do you perform ocular movements when investigating esotropia and what may esotropic results be associated with

A
  • Performed with a light to observe the corneal reflections
  • Tested in 9 positions of gaze
  • These may be full and normal
  • May be associated with superior oblique underactions and inferior oblique overactions with a V pattern, especially in constant esotropias
113
Q

how will you measure deviation on a child who is uncooperative or with poor funicular vision or in babies

A
  • corneal reflections
  • Hirschberg’s, Prism Reflection Test and Synoptophore
  • In babies can only assess using corneal reflections (CR), therefore use Hirschberg’s test or Prism Reflection Test (PRT)
114
Q

how will you measure deviation on a child who is older and with good cooperation

A

use Prism Cover Test (PCT) – most accurate

115
Q

why is it difficult to see the DVD component when measuring the deviation on a child with an esotropia

A

as will see downward movement in both eyes as well

116
Q

on who and how do you perform a controlled binocular acuity test when investigating a esotropia

A
  • Performed on all patients with intermittent esotropia where co-operation allows e.g. 4-5 yrs old
  • Performed at near using the reduced Snellens as a fixation target
  • Test ensures 3DS of accommodation is exerted at I/3m
  • Esotropia will occur as accommodation at 1/3m is exerted in convergence excess
  • Eso deviation not affected by accommodation in near esotropia therefore is present at all times for near fixation and is not affected by exertion of accommodation
  • At near use Reduced Snellen fixation stick and ask child to read down the letter chart
  • Note at which level the esotropia occurs – you will see one eye turn in
  • If the eso deviation occurs when the child starts to read the 6/9 line record the CBA as 6/12 (still binocular)
117
Q

what 2 things does a controlled binocular acuity test differentiate

A
  • between fully accommodative and convergence excess esotropia
    Esotropia will occur as accommodation at 1/3m is exerted in convergence excess
    Eso deviation not affected by accommodation in near esotropia therefore is present at all times for near fixation and is not affected by exertion of accommodation
  • also differentiate between convergence excess and near esotropia
118
Q

how do you record your results from a controlled binocular acuity test when measuring an esotropia

A

If the eso deviation occurs when the child starts to read the 6/9 line record the CBA as 6/12 (still binocular)

119
Q

what is measuring the AC/A ratio important in when investigating an esotropia

A

Important to measure how high the AC/A ratio is in convergence excess type of intermittent accommodative eso, as the aetiology of these patients is a high AC/A ratio

120
Q

how do you measure the AC/A ratio when investigating an esotropia and at what range can the results be between

A

Use the distance gradient method using
- 3.00DS lenses and patient fixes on 6/6 letter (i.e. you do a pct with -3.00DS lenses at a third of a metre)

Results – above 5:1, often as high as 15:1
(normal range is 3/4:1)

121
Q

what does a assessment of binocular function reveal in a patient with an intermittent esotropia

A
  • Binocular function will be demonstrable in these cases as the eso deviation is intermittent
  • Suppression when manifest
122
Q

what does a assessment of binocular function reveal in a patient with a constant esotropia and how is it tested

A
  • In older children e.g. 4 years+ assess state of retinal correspondence to establish presence of potential normal binocular function in recent onset esotropia
  • Easiest to assess on the Synoptophore. The angle of squint is corrected and then assess if any binocular function is present/as a result of that
  • Prisms can be used to correct the squint but it is difficult to assess the state of RC through large prism strengths
  • Abnormal Retinal Correspondence (ARC) is an inferior form of binocular vision
  • ARC develops in constant, unilateral, small angle esotropia
  • The best levels of BV are found in very small eso deviations called microtropias - measures less than 10^
  • Late onset esotropia - likely to find NRC and potential binocular function
  • Large, early onset constant esotropias (infantile esotropia) - many cases have no demonstrable binocular function especially in, a suppression response will be found on all tests
  • Suppression is either unilateral or alternating depending on whether the esotropia is alternating or not
  • Suppression can therefore exist with and without amblyopia
123
Q

when is it unusual for children to complain about their esotropia and why

A

unusual for children to complain of symptoms in constant esotropias because of suppression mechanism

124
Q

which 2 times will a child complain of symptoms with their esotropia and of which type

A
  • Some older children (approx. 6 years or more) complain of diplopia in fully accommodative esotropias when not wearing their glasses
  • Occasionally occurs in convergence excess on near fixation
125
Q

when will a post op diplopia test be carried out and how is it done

A
  • Performed in patients 8 years and over if squint surgery is indicated where there is no binocular function
  • BO prisms are placed in front of esotropic eye starting from BO1^ until the angle of squint is corrected for near and distance
  • The patient is instructed to state if at any time he appreciates diplopia (as want to check if they have any double vision post operatively)
  • Possible responses:
    • If appreciating diplopia, is it easy to ignore the 2nd image? Surgery may be contra-indicated if diplopia is very obvious
    • Diplopia may not be appreciated until the angle of squint is over corrected so surgery is indicated
    • Diplopia may not be appreciated
126
Q

when will botulinum toxin be used to investigate esotropia on a patient and where is it injected

A
  • If the results of the post-op diplopia test are inconclusive or it seems surgery is contra-indicated i.e. as a diagnosis feature
  • Botulinum toxin (BTXA) is injected into the medial rectus muscle
127
Q

what does botulinum toxin do to the eye as a result of being injected into the medial rectus and what can the patient do as a result of this

A
  • This has a temporary paralysing effect on the muscle and straightens the eye and then seen 2 weeks later
  • The patient can then assess more accurately the likelihood of seeing double post-op

Binocular vision YR 3 (20 decks)

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