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Binocular vision, visual impairment and paediatrics > Vision Screening & amblyopia investigation > Flashcards

Vision Screening & amblyopia investigation Flashcards

1
Q

Aim of visual surveillance in child:

A

Early detection of defects that may lead to a permanent visual impairment if left untreated.

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2
Q

What does screening in first year of baby involve:

A
  • Before infants leave hospital
  • 6 week check – bring child to GP and make sure look structurally normal and normal red reflex
  • Other points in child’s life depending on area they live
  • 1 year or 2.5 years
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3
Q

When is the first time children have ocular health screening:

A
  • Before they leave the hospital
  • This involves the dr or nurse checking eyes - look structurally normal and red reflex is present
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4
Q

Which children need to more closely monitored and require more than the screening test

A
  • Children with systemic disease e.g. diabetes, sick cell, neurological or syndrome
  • Premature/low birth weight – cause of risk of retinopathy
  • Family History of strabismus, amblyopia, refractive error
  • Children with hearing loss - cause already have impairment of one their senses
  • Children with a learning disability - children with learning disability 28 X more likely to have problems with eyes or vision
  • If parent worried they saw eye turn in towards nose or GP/health visitor was worried
  • If parents/HV/GP’s detect strabismus require more than the screening test
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5
Q

What is the primary aim of the childhood vision screening programme:

A

To identify children aged 4 to 5 years with impaired sight enabling timely intervention.

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6
Q

What age should children be screened and by who:

A
  • By orthoptists
  • By professionals trained by orthoptists
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7
Q

What age is screening carried out:

A

4 to 5 years old, instead of 3 to 4 years old

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8
Q

Why is screening in 3 years old no longer recommended:

A
  • Due to their young age, they didn’t pass the test not because they couldn’t see but cause they didn’t want to listen or carry out the test
  • So failing of test was cause they were not interested, not because they couldn’t see
  • Cause of that, children were referred into the hospital when it wasn’t needed
  • Lots of false positives cause children were referred into the hospital but turned out to be completely normal
  • Also when it was carried out at 3 years old, the parent had to bring child to GP surgery to have the vision screening, attendance rate high in affluent areas but poor in low income areas = missed target audience
  • Also cause delaying treatment and vision screening (up to ~5 years) will not adversely affect child i.e if they did have defect, their prognosis will not be effected by delaying treatment by 2 years = can still treat well at 4 to 5 years
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9
Q

What is the gold standard screening test:

A
  • Linear logMAR
  • Cause trying to detect amblyopia, which suffers from crowing
  • So best way to detect amblyopia is linear logmar chart
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10
Q

Why is vision screening the only test recommended in children < 7 years old:

A

Cause if children less than 7 had full sight test i.e cover test, motility, refraction, fundus then a proportion of these children would fail test because there young and a lot of tests are being carried out on them, not because of genuine eye problem

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11
Q

What age can you have full regular eye test:

A

After 7

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12
Q

Why is it important to regularly monitor/audit the service:

A
  • Ensure quality of service
  • Cause when carrying out vision screening, don’t want to refer lots of false positives children to the hospital and that the vision screening turns out to be completely normal
  • And don’t want to miss children cause if vision screening test didn’t detect all of the children that genuinely had an eye problem, that would be bad vison screening service
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13
Q

Performing eye test on child:

A
  • Explain the test procedure to the child.
    • Gain consent parent (opt-in/opt-out)
    • Gain consent child
  • Check child is able to match or name the letters at NEAR – to make sure they understand the test before making it harder for them by walking further away and making letters smaller
  • Have a quick practice of the test with the child to ensure understanding – show them card and say look at shapes and point/name same one etc
  • Once understood test, can move further away and make it harder
  • Test each eye separately
  • Avoid pointing inside box – if put finger or pointer inside the box, it will reduce crowding and so make the test less sensitive to detect amblyopia
  • Test right eye first
  • If child has spectacles measure with them on – if find vison poor even with glasses on, these children need to be seen quickly
  • Ensure each eye is occluded properly
  • If poor result with first eye rapidly move onto the second eye
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14
Q

What is the standard recommended method of measuring VA on child:

A

logMAR

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15
Q

When wouldn’t you start with right eye:

A

On child with strabismus
* E.G. if see right turn in eye from a right ESOT
* You wouldn’t start with that eye because if they’ve got a constant right ESOT, chances are they have amblyopia in that eye so cant see well
* Don’t want to start off with worst eye – instead start off with fixing eye

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16
Q

Crowded Keeler logMAR test:

A
  • Designed for use with 3½ to 5 year olds.
  • 3m test distance.
  • Six letters are used X V O H U Y.
  • 4 letters on each line, crowding bars surround each row.
  • Each letter is given a score of 0.025 and each line is 0.100
  • Easy to use, durable, 2 ‘flip over’ books and matching card.
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17
Q

What distance is crowded keeler logMAR:

A

3m

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18
Q

What age is crowded keeler logMAR for:

A

3½ to 5 year olds.

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19
Q

Method for crowded keeler logMAR:

A
  • Six letters are used X V O H U Y.
  • 4 letters on each line
  • Each letter is given a score of 0.025 and each line is 0.100
  • Start with screening card S2
  • If they cant read S2, move to bigger letter i.e S1
  • If they can read all letters on S1, move to S2
  • Last correct letter on S2 indicates the letter size to present as a line of letters
  • Test all letters on the start line once you find the line to start off with i.e by seeing which letters they can read and looking at which logMAR that last letter they read is
  • 4 letters per line must be attempted/correct before proceeding to smaller line of letters i.e if all correct on 0.2, move to 0.1
  • When errors occur test all letters on that line
  • Ask px to identify letters and if they get whole line, go to smaller line of letter size and keep going until px cant see anymore and read the score off based on whether they got 1,2,3 or 4 letters correct
  • Note the line where errors occur and count the number of letters seen correctly on that line
  • Test all letters on 0.200 line if seen
  • Identify the corresponding logMAR score, and record immediately after testing the eye.
  • Change occlusion to fellow eye and test.
  • If got up to U on screener 2, recommendation is to start at 0.200 logMAR line
  • Always point to each letter from either below or above the crowding bars. Do not convert the test into a single letter test by covering some of the line or by pointing to letters from the side.
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20
Q

What is the pass criteria in UK for crowded keeler logMAR:

A

NEED TO SEE AT LEAST 0.200 WITH RE AND 0.200 WITH LE TO PASS

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21
Q

What is the main condition screening is trying to detect and the others you might detect:

A
  • Amblyopia
  • Refractive error
  • Strabismus
  • Nystagmus
  • Ptosis
  • Muscle problem
  • Cataract
  • Anisocoria
  • Rare pathologies
    • Coloboma
    • Leucocoria
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22
Q

Why do we want to treat amblyopia early:

A

If treat it early enough, the prognosis is good, but the longer we wait, the more the prognosis starts to reduce

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23
Q

What is amblyopia:

A

A form of cerebral visual impairment – PROBLEM IN BRAIN, NOT EYE

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24
Q

What does amblyopia result in:

A

Reduced vision in one or both eyes rare in both eyes

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25
Q

What causes amblyopia:

A
  • Arises through an interruption of normal visual development
  • When we are born the visual pathway is not complete
  • Abnormal visual development:
    • Refractive error – causing blurred vision
    • Pathology
    • Strabismus
  • Cause child experiences abnormal version of world where visual pathway is still growing, amblyopia develops
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26
Q

When does amblyopia occur:

A
  • Only occurs during a critical period where the brain i.e the visual pathway is still developing
  • If an adult was to develop a strabismus amblyopia wont develop cause their visual pathway is complete
  • Occurs during critical period (birth to 7-8 years old)
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27
Q

Amblyopia prevalence:

A

Prevalence between 2-4% of the population

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28
Q

Why is vision screening important for amblyopia:

A

SO THE PROGNOSIS FOR TREATMENT OF AMBYLOPIA IS GOOD – LESS GOOD IF DETECTED AS ADULT

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29
Q

What are the 3 periods of VA in children:

A
  • Developmental period = period from birth where vision still growing and developing = Birth to 3/5 years
  • Critical period = period where vision is susceptible to abnormal visual input = after birth to 7/8 years = where amblyopia can develop
  • Sensitive period = t reat amblyopia = from time of deprivation to teenage/adult years = period where treatment is effective
30
Q

What does amblyopia affect:

A
  • Vision/Visual-Acuity – causes vision loss – amblyopic eye
  • Contrast sensitivity
  • Depth perception
  • Difficulty with crowding – so important to use crowded test to detect ambylopia
  • Motion perception – judging fast objects
  • Visual distortion
31
Q

Does amblyopia affect quality of life:

A
  • Yes for treatment–feeling different/bullying – patch
  • But not quality of life – so offer two different treatments – patch or atropine
32
Q

Why is amblyopia difficult to assess if amblyopia affects people:

A
  • Patient cannot determine what it is like NOT to have amblyopia
  • Difficult to separate the affects of amblyopia
    – Reduced V-A
    – Reduced S-A (stereo-acuity)
33
Q

Effects of amblyopia:

A
  • Driving
    • Breaking distances – breaking earlier
    • No. of accidents higher(Maag 1997; Rahi et al., 2006)
  • Navigating around obstacle course (Buckly et al., 2010)
  • Threading beads on a string – look longer (O’Connor et al.,2010 )
  • Reaching & grasping (Grant et al., 2007, 2014,2015,2019)
  • Read slower = due to differences in eye fixations and saccadic eye movements.
  • Reading speed slower and cautious behaviours with eye movement
  • Large number of jobs amblyopes prevented from doing depending upon their level of vision or might find harder e.g. Things like dentistry where stereopsis is important or brain surgery
  • Education(Rahi et al., 2006)
    • Mainly NO difference
      Borderline effect at University level – less amblyopes go uni
34
Q

How does amblyopia affect binocular vision impairment ( BVI ):

A

Amblyopia doubles the risk of BVI
* An amblyopic eye <6/12 (Rahi et al., 2002) is:
○ 49% visual impairment.
○ 23% severe visual impairment or blindness.
○ Only 35% of those in previous paid employment were able to continue
= As we get older, pathology becomes more frequent. If something was to happen to the good eye of amblyopes = that would be detrimental. Study shows when something bad happened to remaining good eye, 50% of people were classed as being VI, ¼ severe VI
* SO WANT TO TREAT AMBYLOPIA CAUSE IF NOT SUCCESSFUL TREATMENT BEFORE, WILL BE CLASSED AS VI IF SOMETHING HAPPENS TO NOT GOOD EYE

35
Q

Classification of amblyopia:

A
  • Strabismic amblyopia
  • Stimulus deprivation amblyopia
  • Anisometropic amblyopia
  • Meridonal amblyopia
    Ametropic amblyopia
36
Q

When does strabismic amblyopia occur:

A
  • Occurs monocularly
  • Occurs in a constant manifest deviation
  • More likely to occur in esotropia
37
Q

Why does strabismic amblyopia occur monocularly:

A
  • Cause amblyopia wouldn’t take place if there was an alteration between the two eyes i.e sometimes the LE is turned in, and sometimes the RE is turned in
  • It prevents bilateral amblyopia
38
Q

Why does strabismic amblyopia occur in a constant manifest deviation:

A
  • Cause if the squint or strabismus was intermittent
  • Some parts of the day both eyes are straight resulting in a normal view of the world and visual pathway develops normally
  • But in constant manifest strabismus, the pathway for that constant tropia eye will not develop normally and will develop amblyopia instead
39
Q

Why is strabismic amblyopia more likely to occur in esotropia rather than exotropia:

A
  • Cause ESOT more likely to be constant
  • EXOT often remains intermittent during childhood so amblyopia doesn’t develop
40
Q

What is stimulus deprivation:

A

Obstruction to the clear passage of light, preventing clear formation of an image for example

41
Q

What is stimulus deprivation caused by:

A

Caused by pathology which could be from
* Ptosis
* Cataract
* Corneal scarring

42
Q

Which eyes does stimulus deprivation occur:

A
  • Occurs monocularly or binocularly
    E.g bilateral cataract both eyes then amblyopia could develop in both eyes
43
Q

When is amblyopia more likely to develop:

A
  • Important to note how much pathology prevents clear image at the macula
  • If the pathology does effect macula, amblyopia more likely to develop
44
Q

What are the types of stimulus deprivation:

A
  • Partial
  • Bilateral stimulus deprivation amblyopia may result from congenital nystagmus – can be both eyes in cases such as bilateral cataract, bilateral ptosis or nystagmus i.e if got pathology in both eyes
45
Q

Examples of partial stimulus deprivation:

A

Developing cataract - if cataract not that dense

46
Q

What can bilateral stimulus deprivation amblyopia be caused by:

A
  • Congenital nystagmus
  • Can be both eyes in cases such as bilateral cataract, bilateral ptosis or nystagmus
47
Q

What is anisometropic amblyopia:

A
  • Difference unequal in refractive error
    • One eye receives better visual input at all distances
  • The refractive error may be spherical and/or astigmatic difference.
  • Amblyopia occurs in eye with larger refractive error
48
Q

Which eyes does anisometropic amblyopia occur:

A

Monocularly

49
Q

What is meridonal (astigmatic) amblyopia:

A
  • A relatively clear image is formed along the more emetropic axis.
  • Eye with larger amount of astigmatism – greater amount of amblyopia
  • A blurred image is formed along the more ametropic axis.
50
Q

Which eyes does meridonal (astigmatic) amblyopia occur:

A
  • Monocularly with anisometropic amblyopia.
  • Binocularly with ametropic amblyopia - if large amount of astigmatism in both eyes
51
Q

What is ametropic amblyopia:

A
  • High degree of uncorrected bilateral refractive error
  • High hyperopia
    • Cannot be compensated for with accommodation can cause bilateral ametropic amblyopia
  • High astigmatic error
  • High myopia
    - Degenerative retinal changes may explain part of the vision loss – check for amblyopia and other pathological changes
52
Q

Which eyes does ametropic amblyopia occur:

A

Occurs bilaterally

53
Q

How to investigate amblyopia - what does the history involve:

A
  • History
    • What is the problem
    • What age did the problem start
    • How long has it been there
    • Strabismus
      ○ Constant/intermittent
      ○ Alternating
  • Refraction (cyclo in children)
  • Ophthalmoscopy
54
Q

When will dense lot of amblyopia be present:

A

If parent says child has tur in eye and from young age, always there

55
Q

When would you prescribe in child:

A
  • The younger the child the larger a refractive error you need before you would consider prescribing
  • Cause when you are born, you’re not born with no refractive error, often can have small amount of refractive error
  • As you grow and the eye grows, the process of emmetropization occurs which starts to reduce levels of refractive error
  • With ansiometropia start prescribing with lower levels than bilateral refractive error
  • With bilateral astigmatism again start prescribing with lower levels
  • Astigmatism – lower threshold for prescribing compared to myopia and hyperopia
56
Q

Normal levels of VA for age:

A
  • Mean V-A using LogMAR tests in 4 to 5 year old children:
    • 0.087 (approx 6/7.5) +/- 0.10 log units for crowded
    • -0.010 (approx 6/6) +/- 0.10 log units for uncrowded LogMAR tests.
57
Q

How to investigate amblyopia - VA:

A
  • Near and Distance
  • Use LogMAR
    ○ Due to crowding phenomenon
  • Name test type
  • With & without compensatory head posture (CHP)
  • If manifest latent nystagmus such as infantile esotropia may want to use spielman occluder to reduce amplitude of nystagmus and help them see more
58
Q

How to investigate amblyopia - contrast sensitivity:

A
  • More sensitive measure than visual acuity
  • Affects are dependant on the type of amblyopia
  • Not practical in younger children
59
Q

How to investigate amblyopia - cover test:

A
  • In children visual-acuity testing not always possible
  • Note whether alternating unilateral deviation – if sometimes using RE, sometimes using LE i.e freely alternating, that means vision is approx. equal
  • Will the amblyopic eye hold fixation to blink
  • Central fixation versus eccentric fixation via corneal reflections (gross only)
  • Is the deviation constant or intermittent
60
Q

What does it mean if child alternating in cover test:

A

Vision is equal

61
Q

Example of left esotropia:

A
  • Px has left esotropia
  • When cover his RE, LE did not move to take up fixation
  • So LE eccentrically fixating cause not using fovea, they are using a point other than fovea to fixate with
  • So vision in LE reduced cause not using macula
  • BUT
  • If cover up RE, LE moves in to take up fixation
  • But when remove occluder, LE moved back out
  • This shows vision is not so good in LE because LE doesn’t want to use that eye to see anything
  • But if the LE remained in once took occluder away and it remained in for a few seconds can show vision starting to improve because px doesn’t mind using that eye for a while
62
Q

How to investigate amblyopia - ocular motility:

A

Patients with incomitancy may be more likely to decompensate when you start occlusion/patching

63
Q

Other tests to investigate amblyopia:

A
  • Accommodation
  • Convergence
64
Q

How to check binocular status in amblyopic px’s:

A
  • Prism Fusion Range
  • Stereopsis
  • Cover test (recovery)
65
Q

Why check binocular status in amblyopic px’s:

A

Ensure that occlusion will not decompensate your patient

66
Q

What is treatment for isometropic amblyopes with straight eyes, i.e the ones with phorias:

A

○ In all isometropic amblyopes with straight eyes, i.e the ones with phorias, the risk with treating amblyopia by putting a patch every day for several hours is not good as it might decompensate these px’s
○ SO WITH THESE PXS CHECK BINOCULAR STATUS
○ To ensure prism fusion range, motor fusion range, stereopsis and cover test recovery is good
○ If these are all good upon each visit, you can continue to treat an isometropic amblyopia
○ If bring them back on visit and notice any of them are starting to worsen then consider stopping amblyopia treatment as there is a risk that it might decompensate them

67
Q

How to measure deviation in amblyopia:

A
  • Prism cover test (if possible)
  • Ensure that occlusion is not increasing the size of the deviation (risk of decompensation)
  • If deviation increase every time they come back – want to consider stopping treatment of amblyopia
68
Q

When would you want to stop treatment of amblyopia:

A
  • If deviation increase every time they come back
  • If density of suppression becoming less, stop treatment
  • If below 10 on sbisa bar = stop treatment because risk of intractable diplopia
69
Q

What else should you measure in all strabismic amblyopes over the age of 5 years and why:

A
  • Measure density of suppression using sbisa bar, neutral density filter or bagollini bar
  • To prevent intractable diplopia
70
Q

Sbisa bar (in patients with suppression):

A
  • So in px with manifest strabismus and amblyopia, i.e strabismic amblyopia, the risk is by treating vision, might improve vision by patching every day but might remove the suppression
  • If density of suppression becoming less, stop treatment
  • If below 10 on sbisa bar = stop treatment because risk of intractable diplopia
71
Q

Ophthalmoscope or visuscope in which ambylopic px’s:

A
  • Should be carried out in all strabismic amblyopes
    • Determine whether eccentric fixation present or not
    • Determine the location of the eccentric point
      ○ Further away from the fovea theyre using to fixate with the worse the V-A = worse prognosis
    • To monitor progress with time
      ○ If treating via occlusion may find the eccentric point changes with time.
      ○ If treating someone with eccentric fixation, it might change over time and find that eccentric viewing point moves towards fovea = vision increase
72
Q

How can you detect the more subtle eccentric fixation:

A
  • In order to detect the more subtle eccentric fixation, ophthalmoscope or visuscope required
  • This is to measure if eccentrically fixating or not:
    • Occlude untested eye.
    • Examiner projects the fixation target onto the fundus close to the fovea.
    • Patient is instructed to look directly at the centre of the circle – USE THIS SETTING ON OPTHALMOSCOPE
    • The position of the fixation target on the fundus is then noted.
    • There is a decrease in visual acuity with increasing distance from the fovea.
    • If look at the centre of the circle using fovea = should see fovea reflex in middle of circle
    • If not in middle of circle – need to record where it is
    • The further away the foveal reflex from the circle = worse VA

Binocular vision, visual impairment and paediatrics (6 decks)

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