Optometric examination of children part 2 Flashcards
what does an accurate refraction help with in a child
establish if child’s visual system is developing normally, which is the first thing you want to ask yourself
what does correcting ametropia allow for in a child and what may it explain
- Allows child to achieve maximum possible VA
- May explain lack/reduction in BSV
i. e. give clues about whether their refractive error is normal or not
what are auto refractor readings found to be in children under:
non-cycloplegic conditions
and
cycloplegic conditions
- Under non-cycloplegic conditions, tends to overestimate myopia
- shown to be accurate under cycloplegia
so use with caution, some clinicians use it to aid their RET results
what is found to be more accurate than an auto refractor
retinoscopy by experienced clinician
what are the 3 different available methods for ascertaining refractive error using retinoscopy
- Static (or dry)
- Mohindra technique
- Cycloplegic refraction
what is dynamic retinoscopy used to assess in children
their accommodative state
what is meant by static or dry retinoscopy
which target needs to be used
how should it be done
which 2 ways can it be done and what can be a drawback to one of these ways
= Static = static accommodation i.e. relaxed
- Use distance fixation target e.g. clown
- Children’s trial frame
- Hold lenses in front of both eyes
Neutralise each meridian separately - 50cm working distance may be more appropriate
Make adjustment for working distance - Remember to fog contralateral eye
- Needs to be quick (due to short attention span)
- Can be done awake or asleep
- Bell’s phenomenon may be a problem if asleep as eyes can roll up if sleeping
what is the working distance for static/dry retinoscopy
50cm = -2.00D
list 3 things that have been found about refractive error with static/dry retinoscopy on a pre school/young child
- Tends to result in spherical error more negative i.e. less positive (by up to 4DS)
This can occur into teenage years - Little difference between measurements of astigmatism
- Non-cycloplegic static retinoscopy far less reliable in paediatric subjects
when will it be desirable to do a cycloplegic refraction and give 8 reasons when it is essential to do
desirable:
in all new cases, for a baseline measurement
essential:
- reduced stereopsis
- reduced V/VA to get the true refractive error
- suspect or manifest strabismus
- large decompensating esophoria (will tell us if theres any latent hyperphoria or hyperopic element)
- FH strabismus or high hypermetropia
- suspect pseudomyopia
- anisometropia > 1D
- poor accommodation
what is pseudo myopia
when the visual state is pretending its myopic, as if its gone into an accommodative spasm, so they’re not really myopic, they just need to relax their accommodation
list 3 advantages of a cycloplegic refraction
- Reveals latent hyperopia
- More accurate refraction
- Aids fundus check (as it dilates the pupil)
list 4 disadvantages of a cycloplegic refraction
- Photophobia
- Distress (sting from drops)
- Temporary near vision problem
- Risk of adverse reaction
list 4 adverse reactions to cycloplegia
which 2 affects it has
which group of children have increased sensitivity to cycloplegics
“blind as a bat” = vision blurry
“dry as a bone” = thirsty
“red as a beetroot” = flushed cheeks
“mad as a hatter” = sleepy
CNS effects
Local effects
children with Down’s syndrome increased sensitivity to cycloplegics
when will you give Cyclopentolate HCL 1%
when will you give Cyclopentolate HCL 0.5%
what allowance is not made
when does maximal cycloplegia occur
how much residual accommodation is left
what does it not always produce
Cyclopentolate HCL 1%:
> 6 months
Cyclopentolate HCL 0.5%:
12 years (if think pseudo myopic)
if light irides
- No tonus allowance made (don’t tweak rx after drops)
- Maximal cycloplegia 10 – 55 minutes
- Residual accommodation 1.00 - 2.50D
- Does not always produce adequate cycloplegia
what should you do before starting your ret and after instilling cyclopentolate drops
check for any residual accommodation
write down the time of putting the drops in
which 2 ways is advised to instil the cyclopentolate drops
what do some practitioners use with it and why
- Drop onto lashes of closed eye
- Use atomiser (spray used in hospitals) (availability limited)
Some use Proxymetacaine HCL 0.5% first
- Prevents stinging but child may object to cyclo drop
- Increases absorption
when will you use 1% Cyclopentolate AND 1% Tropicamide
why will you choose to use this combination over atropine
what is the residual accommodation with this
- Cycloplegic refraction in African children i.e. very dark iris
- Less toxic than Atropine
- Residual accommodation 0.63DS
why will you not decide to use 1% atropine
which types of clinicians are more likely to use it
how much residual accommodation is there
what is the tonus allowance
- Severe side-effects; risk of poisoning
- Additional Supply or Patient Group Direction
- Residual accommodation 0.04D
Tonus allowance:
- 1.00DS for low myopes/hyperopes
0. 00DS for moderate/high myopes
what is the mohindra retinoscopy technique also called
how is it done
what is the fixation target
what is the working distance
what will you do differently with the working distance and why
- Also called near (monocular) retinoscopy
- On one eye at a time (occlude one eye)
- Carried out in a totally dark room
- Light of ret used as fixation target
Assumes eye is in normal resting state - 50cm working distance (= 2DS)
- Mohindra: subtract 1.25DS from findings
- allowing for 0.75DS accommodation that went on because of light stimulus
list 3 rules of thumb when carrying out subjective refractive error on children
- Don’t attempt if child
when will you measure accommodation on a child
which children will you do it on
how will you do it if doing subjectively
what can be difficult with this
- Do before instilling cycloplegic drops
- In older children
- Check N5 acuity at 5cm
- Use budgie stick
- Or RAF rule
- Push-up method
- Requires subjective response – unreliable
- Difficulty interpreting blur point
which type of subjective accommodation test will you use on a child
what is it used to assess
what is it useful in
what is it NOT used for
when and how will you do it
what are the normal findings
what does abnormal findings indicate and how may you want to manage them
- Dynamic retinoscopy
- Used to assess accommodative state
- Useful if suspected accommodative insufficiency
- NOT used to assess refractive state
- After ret
- With distance Rx
- Check for symmetry
- Only need to check along single meridian
- Child fixates accommodative target in plane of retinoscope (ask what pics they can see)
- Room lights so child can see targets!
- In theory, neutral should be found at child’s working distance
- In reality, small with movement observed
- +0.25 to +1.00DS lag is normal
- if more then px has insufficient accommodation
- may want to prescribe bifocals or try to manage with the refractive error we have found
how is the Nott and the MEM method of dynamic retinoscopy carried out
- Nott method Patient fixes a target in plane of retinoscope Distance correction in place With movement noted Move ret forward until reversal noted Dioptric distance equals accommodation
- MEM method (Monocular Estimation Method)
Movement neutralised with positive lenses
