lecture 7 paediatric optometry - accommodation and cycloplegic refraction

What are the different tests for accommodation:

- Amplitude of accommodation

- accommodative facility

- relative accommodation

What is amplitude of accommodation?

A measure of the maxmimum amount of accommodation that can be exterted

- it is the difference in dioptres between the far point and the near point of accommodation relative to a reference point

what is aoa at 10 years old

around 14 D

aoa and value of 0

aoa never goes to 0

What happens to AoA as we get older?

decreases

- this becomes symptomatic at approx 45 years of age

What effect does the pupil have on the depth of focus?

smaller pupil = greater depth of focus

- makes the aoa measurment more subjective

- aoa measurement does not take into account pupil size

What is Hofstetter's formula?

it can be used to derive the expected AA of accommodation for caucasian subjects up to 60 years of age

3 ways of measuring aoa - differences

-dr - does not take into account depth of focus as much , it is an objective method

- subjective methods of aoa have higher values than dr , so it overestimates the aoa

- dr may have more accommodation and more fluctuations

3 ways of measuring aoa - the highest to lowest values of aoa

- highest D - push down

- minus

- dr

whem to do aoa

after patient is fully refracted

- if not worn the measure of aoa would have to be adjusted

how is NPA meaured

push up and push down method

monocular and binocular

what is the equivilent of npa ( puntum proximum )

is the aoa

push up method - estimation of aoa

- likely to overestimate

- may move the reference after the pateint realised it is blurred

how reduce the fluctuations in results of aoa to prevent over/underestimation

- do both push up and push down

- find the average

- do it slowly

How do you work out the maximum amplitude?

25-0.4(age in years)

How do you work out average amplitude?

18.5-0.3 (age in years)

How do you work out minimum amplitude?

15-0.25 (age in years)

What is accommodative facility?

Ability of Px to rapidly change accommodation

hashemi et al aoa normal values in practice

between minnimum and average values

What is the test for accommodative facility?

- measured at 40cm ( A Demand 2.5)

- target is N5 or N6

- refractive error is fully corrected

- show plus and minus 2D lenses ( makes ad 0.5)

- test i s started with the patient trying to clear the letters through a +2D lens

- then through the -2D lens ad is 4.50 D

What are the clinical pass rates for the test on accommodative facility?

- 7 cpm monocular - better as only reflex accomodation used

- 5 cpm binocular - takes into account vergence accommodation too

why is normative data difficult to use

- evidence base isnt great

- poor exclusion criteria

- range of ages used

What are some accommodative disorders?

- accommodative insufficiency

- accommodative fatigue

- accommodative spasm

- accommodative inertia

What is accommodative insufficiency?

accommodation is less than expected for someone of their age

What are the symptoms of accommodative insufficiency?

blurred vision at near

frontal headaches

what is the criteria of accommodative insufficiency

less than minimum aoa of hofstetters formula

What are the signs of accommodative insufficiency?

- reduced AoA

- reduced accommodative facility

- reduced near vision/VA

- XOP at near becomes esophoric if Px tries to exert more accommodation

difference between accommodative insufficiency and accommodtative fatigue

accommodative fatigue is similar but more transient and usually appears more in the evening

What is the treatment for accommodative insufficiency?

Hyperopic Rx

- low add may be needed: if too high may prevent accommodative response acting as it should

- pen to nose exercises (can be related to convergence insufficiency)

What is accommodative inertia?

- more prevalent in adults over 30

- accommodation system has difficulty switching for DV to Nv AND BACK

What are the causes of accommodative inertia?

- prolonged near work

- poor genera; health

- anisometropia

- early presbyopes

- holmes adie syndrome

What are the signs of accommodative inertia?

Reduced AoA

Reduced accommodative facility

What is the treatment of accommodative inertia

any underlying conditioterm-64ns should be treated

- refractive error corrected

- push up exercises/ flipper exercises can help

what muscle aids accommodation

cilary muscle

What is accommodative spasm?

- AKA accommodative excess

- constant contraction of the ciliary muscles leads to exertion of accommodation

What are the causes of accommodative spasm?

- uncorrected hyperopia ( pseudo myopia takes place in refraction )

- prolonged near work

- underlying emotional cause

- lesions of the brain

- MS

- meningitis

- head trauma

What are the symptoms of accommodative spasm?

- pseudomyopia

- headaches

- ocular discomfort

- esotropia and pupil miosis in more defined cases ( triad affected )

What is the treatment of accommodative spasm?

hyperopia should be gradually corrected

- in more pronounced cases cycloplegics can be used (orthoptic exercises needed to prevent a reoccurrence)

how to rule out pseudomyopia

- cylcoplegic refraction

What are the indications for the use of cycloplegia?

- young children

younger than and first eye exam

younger than 4 and repeated eye exams

- subjective refraction is limited

- dry ret difficult

- latent hyperopia

- case history (problem focusing)

- suspected accommodative disorders

reduced aoa

reduced acommodative facility

lag of accom greater than 1

lead of acommodation

What is cyclopentolate?

- muscarinic antagonist

- prevents the eye from accommodating

- dilates the eye

diffrences in subjective and ret in pateints with latent hyperopia

- dry subjective less postive than retinoscopy

- retinoscopy more plus than subjective

college of optometrists guidelines of cycloplegic agents in children- when to consider use

• You should consider use of a cycloplegic agent

to give:

a) an accurate assessment of the refractive error,

which is the major factor in amblyopia or squint

b) the best possible view of the fundus, within the

limits of the co-operation of the child

What is the dosage for cyclopentolate?

for children aged 3 months to 11 years: apply 1 drop, 30 to 60 minutes before examination, using 1% eye drops

For children 12 to 17 years: Apply 1 drop, 30 to 60 minutes before examination. using 0.5% eye drops

What are the side effects of cyclopentolate?

- blurrd vision

- photophobia

very rare- with 2% and multiple 1% drops

- psychosis

- hallucinations

- ataxia

- incoherent speech

What should you check after instilling cyclopentolate?

- check accommodation has been relaxed

- check for anisocoria

- drops take 30 mins at least to work

what to check before instillation of cyclopentolate

- informed consent

- explain why we want to use clyloplegia

- explain visual affects -

near vision blur

pupil dialtion

increased light sensitivity

- explain drops will sting a little

- may need other optom to put drops in

check allergies

What needs to be recorded when you instil any drug?

- drug name

- dose

- batch number

- expiry date

retinoscopy after cycloplegic drops

focus on the centre

pupil periphery may be affected by abberations and may have different reflexes