5/6 - measuring RE and cycloplegia

What are objective RE measurements in kids?

1. retinoscopy

2. autorefractors

3. photorefractors

At what age is subjective refraction attempted?

age 6

When do you start to get reliable subjective refraction results?

age 8

what are the advantages of distance (static) retinoscopy?

portable, reliable and easy to control

What ages do we do distance (static) retinoscopy with loose lenses or lens bars?

under 5-6 years old

what are some static retinoscopy tips?

1. use an interesting target → video

2. estimate magnitude based on motion (brightness and speed of reflex)

3. wait for plus (with motion), then fog fellow eye with more plus power to unmask hyperopia

What age should we not do distance (static) retinoscopy on?

under 2

What are the testing conditions for Mohindra (near) retinoscopy?

1. extremely dark room

2. 50 cm working distance

3. monocular

4. child views retinoscope light

what happens to accommodation when child views retinoscope light during Mohindra (near) retinoscopy?

light is poor stimulus to accommodation → accommodation in resting state/dark focus

What ages is Mohindra (near) retinoscopy used for?

children under 3 → use loose lenses

What do you record for mohindra retinoscopy in a kid under 2?

subtract 0.75D from gross lens

What do you record for mohindra retinoscopy in a kid over 2?

subtract 1.25D from gross lens

What is a downside to the Mohindra (near) retinoscopy technique?

often under-plusses hyperopes

what is dynamic retinoscopy?

modified MEM technique → neutralizing reflex to an accommodative stimulus

What are the testing conditions for dynamic retinoscopy?

1. dim room

2. 50 cm working distance

3. binocular

4. child views examiner

What do you record for dynamic retinoscopy?

gross lens → do not minus working distance

What is dynamic retinoscopy used for?

lead and lag

1. to estimate refractive error

2. hyperopia → estimates cycloplegic RE, can confirm if patient can compensate for their hyperopia

what presents in convergence excess/accommodative esotropia?

high lag found during dynamic retinoscopy

in order to compensated for high ac/a

What does it mean if you get a low rx on dynamic ret and then a high rx on cyclo?

kid has good accommodation to overcome hyperopia → do not need to rx full amount

What does it mean if your dynamic ret is close to your cyclo ret?

kid has low accommodation + cannot overcome their hyperopia → prescribe more +

How should you start your subjective refraction with a kid?

test their reliability (if good VA after ret):

add 1D of plus → did it make blurry?

change axis by 20-30º → see if they bring you back

What do you do if you start subjective refraction and they cannot give you good answers?

document that refraction was attempted but not reliable

how do you perform the rest of subjective refraction on a kid?

same as adults

How much past the first 20/20 can you go in a kids refraction?

no more than 0.50 past first 20/20 → don't over-minus + check cyclo ref

is cycloplegia optional for children?

NO → standard of care

When must you cycloplege a kid?

1. 1st visit to your office

2. inconsistent acuities with dry ret

3. low confidence in dry ret

4. esotropia, large esophoria, anisometropia, amblyopia

5. suspect latent hyperopia

How should you do ret in a cyclopleged kid?

if older than 2-3: have them fixate at distance (on a movie)

if <2 years: have them fixate to you → still subtract working distance bc not accommodating

After cycloing a kid, what parts of the refraction should you do?

push plus in the sphere (no cyl)

what is the MOA of adrenergic agonists?

stimulate iris dilator muscle → less effect on accommodation

what are the adrenergic agonists?

1. 2.5% phenylephrine

2. hydroxyamphetamine

3. Paremyd (0.25% tropicamide and 1% hydroxyamphetamine)

what are the SE of adrenergic agonists?

cardiovascular events

What are the contraindications of adrenergic agonists?

1. cardiovascular problems

2. younger than 1 year

3. need cycloplegia

4. never more than 3 gtts of 2.5% PE separated by 5 minutes

what is the MOA of cholinergic antagonists?

paralyze iris sphincter muscle → severely affects accommodation

what are cholinergic antagonists?

0.5%, 1% tropicamide

0.5%, 1% cyclopentolate

0.5%, 1% atropine

When does the max effect of cycloplegia from tropicamide occur?

30 mins

How long does the cycloplegia from tropicamide last?

4-8 hours → near vision returns in 2-4 hrs

Tropicamide is considered an incomplete cycloplegia for what groups?

1. suspected high hyperopia

2. accommodative esotropia

3. refractive amblyopia

When does cyclopentolate take full cycloplegic effect?

45 mins → satisfactory after 30 mins

How long does cyclopentolate last?

24 hours → make sure to tell patients

what is cyclopentolate good at? bad at?

good cycloplegia

not good dilator

What are the side effects of cyclopentolate?

1. irritability

2. blushing

Which drug gives us maximal cycloplegia?

atropine

How long does atropine last?

1 week

What are the side effects of atropine?

1. irritability

2. blushing

3. dry mouth

4. poor vision

Which patients are more likely to suffer side effects from cycloplegics?

1. Down syndrome

2. CNS problems

3. lightly pigmented

what is better at finding latent hyperopia, cyclopentolate or tropicamide?

cyclopentolate finds 0.175D more plus than tropicamide

Who do we cycloplege with cyclopentolate?

1. infants

2. high hyperopia

3. strabismus

4. inconsistent/variable exam results

how does crying affect findings?

significantly less hyperopia was found for subjects crying in all cycloplegic conditions

what factors must you consider when choosing cycloplegia drops?

1. age

2. iris color

3. RE

4. if previously cycloplegged

5. tolerability of pt

What drops should you use to cycloplege a patient under 1 years old?

1 drop each:

0.5% cyclopentolate

0.5% tropicamide

What drops should you use to cycloplege a patient older than one years old that's new or known pt with hyperopia, esophoria/estropia, anisometropia?

1 drop each:

1% cyclopentolate

1% tropicamide

What drops should you use to cycloplege an older child (~teen) with suspected low hyperopia or an established hyperope?

2 drops of 1% tropicamide (sep by 5 mins)

What drops should you use to cycloplege an older child (~pre-teens and up) with no problems or with myopia?

1 drop of 1% tropicamide

What age can you start giving phenyl?

3 years old

What do you suspect of your auto refractor result in a kid?

suspect it is underplussed if child if not done with cycloplegia

What is photo refraction?

light flashed at eye → reflex off retina tells you script

What is the photorefraction reflex of an emmetrope?

red reflex

What is the photorefraction reflex of a myope?

crescent on same side of flash

What is the photorefraction reflex of a hyperope?

crescent on opposite side of flash

What does it mean if the pupil is filled with white on photo refraction?

ametropia is greater than ±6.00D

What does a bigger crescent mean on photorefraction?

larger ametropia

How do you get astigmatism RE with photorefraction?

flash in 2 meridians

What else does the photorefraction machine estimate besides RE?

strabismus via Hirschberg reflex and Bruckner reflex

What does it mean if your photorefraction is blue over the iris?

corneal opacity

What does it mean if you photorefraction is blue or black over the pupil?

cataract

What is the main advantage to photo refraction?

can be performed by lay person

What are the downsides to photorefraction ?

1. fixation

2. misses high hyperopes

3. age and pupil size dependent