pediatric refraction - cybersight · subjective refraction ... binocular balancing ... – fogging...
TRANSCRIPT
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Pediatric refraction
Bayasgalan Oldokh, MD, Resident of Ophthalmology
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Pediatric vision development Age Visual characteristics Stereoacuity
Birth – 4 months
- Conscious fixation on near objects
- Development of sensory & motor
fusion
Not present
5-8 months
- Good color vision- Fovea well developed- Some sensory & motor
fusion
Begins at 5 months
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Pediatric vision development Age Visual characteristics Stereoacuity
9 – 12 months
- Able to grasp objects- Sensory and motor
fusions well developed
Can judge distances fairly well and throw things with precision
1-2 yearsHighly interested in
exploring their environment looking
and listening
Well developed
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Pediatric Ophthalmology and Strabismus. David Taylor, Creig S Hoyt. 2012
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Good vision
Alignment of visual axes
Intact cortical mechanism
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AL change in respect to age
Refractive development of human eye. Arch Ophthalmology. 1985; 103(6):785
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Keratometry values in respect to age
Refractive development of human eye. Arch Ophthalmology. 1985; 103(6):785
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Lens power in regard to age
Refractive development of human eye. Arch Ophthalmology. 1985; 103(6):785
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Emmetropization“The total emmetropization process occurs mostly during thefirst 4-5 years of life with both initial myopia and hyperopiaconverging on low hyperopia and by 6 years, 80% of children arefound to be emmetropic”
Thorn B, Bauer J et al, 1996
“At birth the average amount of astigmatism is predicted to be2.98D, decreasing to 0.50D by 2.5-5 years of age”
Mohindra I, Held R, 1991
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Emmetropization
Active process Passive process
• Regulated by retinal image
• Visual deprivation causes the eye to elongate
• Physical and genetic determinants of normal eye growth
“Development of highametropia, usually because ofaxial length is the result ofgenetic inheritance”
Sorby et al 1998
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Refraction
Objectiverefraction
• To obtain an objective measurement of the patient’s refractive status• e.g: keratometer, retinoscope, autorefractometer, etc
Subjectiverefraction
• Determines the refractive status using combination of sphere & cylindrical lenses that artificially place the far point of each eye of patient at infinity
• Provide best VA without accommodation relaxed
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Objective refraction
Manifest “Dry”
Cooperative patients
Cycloplegic“Wet”
Uncooperative patients
Strabismus
Latent hyperopia
Suspected pseudomyopia
Inconsistent end point of
refraction
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Uncooperated patients (8 years or younger)
With strabismus
Latent hyperopia
Pseudomyopia
Inconsistent end point of refraction
Indications
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Cycloplegia: Relaxes ciliary muscle + iris sphincter
Mydriasis: Contracts iris dilator
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Cycloplegic agents Agent Dosage Duration
of effectResidual
accIndication
Atropine sulfate 1%
1 drop x 2 30 min; wait 1 hour
10-14 days Negligible • Strabismus (esp ET)• Spasm accomodation
Homatropine2%
1 drop q 5 min x 2;wait 1 hour
1-3 days Negligible
Scopolamine 0.25%
1 drop q 5 min x 2;wait 1 hour
3-7 days Negligible
Cyclopentolate1%
1 drop q 15min x 2; wait 50 min
24 hrs Minimal • Strabismus• Younger children
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Management of refractiveerrors
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Myopia• Lowest spherical equivalent with best VA
Pediatric Eye Disease Investigator Group (PEDIG)
• Antimuscarinic agents (atropine 0.01%) significantly reduced the progression of myopia
Five-Year Clinical Trial on Atropine for the Treatment of Myopia, Audrey Chia et al, Ophthalmology 2015;1-9
Pathologic Myopia
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Hyperopia • Highest spherical equivalent with best VA
Pediatric Eye Disease Investigator Group (PEDIG)
• Children with hyperopia >=+3.50 had 13 times greater risk of developing strabismus and amblyopia
Two infant vision screening programmes: prediction and prevention of strabismus and amblyopia from screening. Atkinson J et al. Eye 1996; 10: 189–98.
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EsotropiaTypes Optical correction
Infantile ET • Hyperopia occurs in 50% of children with IET
• Hyperopia – FOC Fully accomodative ET • FOC
High AC/A ratio accomodative ET
• Bifocals = FOC + (+)lens at near fixation
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Exotropia
Types Optical correction
Intermittent XT Mild to moderate hyperopia: not corrected
High hyperopia: FOC
Myopia: FOC/overminus
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Pediatric Eye Evaluations Preferred Practice Pattern, 2012
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Refraction
Subjectiverefraction
Objectiverefraction
• To obtain an objective measurement of the patient’s refractive status• e.g: keratometer, retinoscope, autorefractometer, etc
• Determines the refractive status using combination of sphere & cylindrical lenses that artificially place the far point of each eye of patient at infinity
• Provide best VA without accommodation relaxed
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Cooperated patients (8 years or older)
Without strabismus
Consistent BCVA
Indications
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Sphere check
Cylinder axis refinement
Cylinder power refinement
I
II
III
Steps I-IV for the other eyeV
+1 testVI
IV Duochrome test
Binocular balancingVII
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Asthenopia• Subjective symptoms of:– ocular fatigue – discomfort– headache arising from eyes
• Etiology:– Accomodative asthenopia– Muscular asthenopia– Nervous asthenopia
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+1 test
• Control of accomodation
Myopia
• Can be over-minused• Refraction can show
more minus • Person will get
spectacles that are too strong
Hyperopia
• Can be under-plussed• Refraction can show
less plus • Person will get
spectacles that are not strong enough
ASTHENOPIA
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+1 test (1/2)
STEP 1 Remove the occluder so that both eyes can see thedistance VA chart.
STEP 2 Measure distance binocular VA
STEP 3
Take two +1.00 D lenses from the trial set and put onein front of each eye
!By adding plus, the accommodationshould relax.
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+1 test (2/2)
STEP 4Measure binocular VA again (with these extra +1.00 D lenses).The VA should be between two and four lines worse.
STEP 5If the VA is more than two lines worse: Binocular balancingIf the VA is the same or only one line worse → Step 6.
STEP 6
If the VA is the same or only one line worse → add+0.25 D to both eyes.
!
If the VA is the same or only one line worse, the person is given too much “-” (or not enough “+”) The person was accommodating during your refraction.
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Binocular balancing
• Final important step of subjective refraction• Purpose: equalize accomodation between 2
eyes• Types:– Fogging test – Alternate occlusion test– Vertical prism dissociation – Polarized or Vectographic– Turville infinity balance
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Binocular balance method (1/2)
STEP 1 Measure the right eye VA (occlude the left eye).
STEP 2 Measure the left eye VA (occlude the right eye).
STEP 3Add +0.25 D to the better eye.Measure the VA of this eye.
STEP 4 Repeat step 3 until the VA of both eyes is almost the same.
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STEP 5Ask the person to keep both their eyes open.Ask the person to look at a small letter that they can see.
STEP 6 Quickly occlude first the left eye, then the right eye.
STEP 7If the person tells you that one eye is clearer than theother eye add +0.25 D to the eye that sees better.
STEP 8Repeat until the person tells you that both eyes are equally clear
Binocular balance method (2/2)
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the CLEAREST and the MOST COMFORTABLE
vision