TOPIC 5: Rx Flashcards
state expected VA at 6 months, 1 year, 2 years and 3 years old
6 months: 6/60-6/36
1 year: 6/24
2 years: 6/12 - 6/9
3 years old: 6/9-6/6
what are the refractive norms for premature infants?
Shorter axial lengths, shallower anterior chambers, and more highly curved corneas than eyes of full-term infants.
Premature eyes develop less of the expected hypermetropia in full-term eyes, mainly due to differences in ACD and corneal curvature.
Higher prevalence of myopia as compared to full term infants
Myopia decreases as the child grows
what are the refractive norms for full term infants?
Low to moderate hyperopia decreasing with age
Low to moderate astigmatism, decreasing over the first year
10 Signs and symptoms of uncorrected refractive error in young children?
Difficulty with depth perception
Eye hand and coordination difficulties
Frequently rub eyes
Blink Excessively
Cannot maintain fixation on a task
Frequently closes or cover one eye
Lack of interest in outdoor activities
Lack of interest in near task
Squinting
No signs or symptoms
state the SSx of myopia seen in kids below 5
Low magnitude: No Sx
High magnitude: Lack of interest at distant object or get close to toys, books or TV
state the SSx of myopia seen in kids above 5
Hold book close
Squint to see writing board
Fail vision screening
Poor VA at all distance
state the SSx of hyperopia seen in kids below 5
Low magnitude: No Sx
◦Mod to High magnitude:
Possible esotropia?
Lack of interest in near task
poor eye-hand coordination and perceptual skills
state the SSx of hyperopia seen in kids above 5
Low magnitude: No Sx
Mod magnitude:
Lack of interest in near task
Poor reading skills
Asthenopia
High magnitude: Reduced VA at distance and near
state the SSx of astigmatism seen in kids below 3 and age 3-5
below 3:
No Sx
age 3-5:
◦Reduced VA?
◦Decreased interest in fine detailed task
state the SSx of astigmatism seen in kids above age . state the changes in astigmatism as a child grows
◦Reduced VA at distance and near
◦Asthenopia?
As a child grows, it is unlikely to have any significant change in amount or incidence of astigmatism
state the SSx of anisometropia seen in kids below age 4
◦Possible no Sx
◦Decreased stereopsis or other BV skills
◦Amblyopia
state the SSx of anisometropia seen in kids above age 4
◦Decreased stereopsis or other BV skills
◦Amblyopia
◦Asthenopia
When should refraction be conducted? why?
Before BV assessment
clear retinal image and balanced correction both eyes.
important as: there may be cases of Fully-Accommodative Esotropia which can be corrected with the use of spectacles.
state the age group, illumination, TD and target for near retinoscopy. How much to minus from results?
Useful: Birth to 3 yo or even older child
Room illumination: Total darkness
Testing Distance: 50 cm
Target: Child fixate at retinoscope beam source (low)
Points to note: Use sounds like bells or squeaky toys to attract child attention
Rx = Gross findings - 1.25 DS
Recorded finding is the total power minus accommodative effect
what are the values to subtract from gross findings by age in near retinoscopy?
< 2 years old: 0.75D
≥ 2 years old: 1.25D
state the age group, illumination, TD and target for static/distant retinoscopy. any points to note?
Useful: Age 3 or above
Room illumination: Dim
Testing Distance: 50 cm/67cm
Target: Appropriate fixation target
Consider refracting glasses that fog vision
Occlude one eye/use prism when strabismus present
what are the indications for cycloplegic refraction?
- Fluctuating reflexes
- Inability to fixate
- Uncooperative
- Strabismus (esp. esotropia)
- Suspected latent hyperopia
- Amblyopia
- Anisometropia
- High lag of accommodation
3 different type of cycloplegia is available?
-Cyclopentolate 1%
2 drops (< 3 drops), 5 mins apart, wait for 30 – 45 min
≤8 lbs , 0.5 %; ≥15 lbs, 1.0%
In hospitals: Cyclopentolate 1% is used.
1st drop: local anaesthesia (LA)
2nd and 3rd drops: Cyclopentolate
*Each 5 minutes apart
Refraction can be done 30 minutes thereafter.
-Atropine
Used more in hospitals, especially for esotropic children
-Cycloplegic spray
Useful for some uncooperative child and light iris
Consist of: 2% cyclopentolate, 1% tropicamide, 10% phenylephrine
(Other: Apply on child’s closed eyelid actually consist: 0.5% cyclopentolate, 0.5% tropicamide and 2.5% phenylephrine)
state the age group, illumination, TD and target for photorefraction. any points to note?
Useful: From birth
Room illumination: Depends on model
Testing Distance: Depends on model
Target: Depends on model
Look at amount and position of Whitish crescent formed (red reflex)
Primarily a screening technique which allows for estimation of refractive error
minimal dioptric range for photorefraction? what raeadings given?
Minimal dioptric range:
Can detect as little as 0.5D
Not able to quantify > 6.0D
Also useful to detect strabismus, anisocoria, media opacities
Photorefractor gives the following readings:
Refractive power
Pupil size
Gaze centration.
state the age group, illumination, TD and target for autorefraction. main uses? disadvantages?
Useful: Useful for above age 3
Room illumination:
Testing Distance: Depends on model
Target: Attractive fixation target
To estimate/confirm Rx
Less effective for screening very young child
Useful for very significant Rx
what is keratometer and keratoscope useful for?
Both useful for above age 3
Keratometry is useful in examination of cylindrical component, especially if retinoscopy is difficult.
Useful to confirm presence of significant astigmatism in young or uncooperative child
how does keratoscope work?
Works similarly to corneal topography
Internally illuminated placebo disc
Pattern of disc reflected on cornea
Pattern elongated when astigmatism is present (1.50D or above)
Cylinder axis is along elongated meridian
5 tips for retinoscopy on infants?
Use trial lenses (hold them in front of eye) or a lens rack
- Note BVD if Rx is high
Arrange appointment at meal time
- Perform retinoscopy while baby being fed
Perform retinoscopy while baby is asleep if eyes not too elevated
Position yourself as needed
- Stand if necessary
If cyclo refraction is clearly needed, do not upset the child/parent doing a non-cyclo exam!
8 tips for retinoscopy on toddlers?
Use loose lenses or lens bar/rack with a trial frame (if possible)
Appropriate appointment time
Let child look at retinoscopy light before starting retinoscopy to satisfy his/her curiosity
Ret the important eye 1st!
- concerned eye that you need to know the findings most
Control accommodation as much as possible and believe the most plus reflex
Neutralize center of reflex
(Large Pupil = Spherical Aberration)
Decide on accuracy needed
Work fast!
tips on controlling accomo?
Use an interesting target
Fixate at 6metres
Trial frame with WDL and fogging for older child Neutralize and push for MAX plus
Use a cycloplegic if indicated (the best way!)
What kind of refraction to be done for <3 years and 3-5 years?
< 3 yrs:
Near retinoscopy
Cycloplegic refraction
3 – 5 yrs:
Distance retinoscopy
Cycloplegic refraction
Subjective refraction (if possible)
*Autorefraction, photorefraction, keratometry and keratoscopy taken as screening tool and/or confirmation tool only
