Pediatric refraction

Bayasgalan Oldokh, MD, Resident of Ophthalmology

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

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

Pediatric Ophthalmology and Strabismus. David Taylor, Creig S Hoyt. 2012

Good vision

Alignment of visual axes

Intact cortical mechanism

AL change in respect to age

Refractive development of human eye. Arch Ophthalmology. 1985; 103(6):785

Keratometry values in respect to age

Refractive development of human eye. Arch Ophthalmology. 1985; 103(6):785

Lens power in regard to age

Refractive development of human eye. Arch Ophthalmology. 1985; 103(6):785

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

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

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

Objective refraction

Manifest “Dry”

Cooperative patients

Cycloplegic“Wet”

Uncooperative patients

Strabismus

Latent hyperopia

Suspected pseudomyopia

Inconsistent end point of

refraction

Uncooperated patients (8 years or younger)

With strabismus

Latent hyperopia

Pseudomyopia

Inconsistent end point of refraction

Indications

Cycloplegia: Relaxes ciliary muscle + iris sphincter

Mydriasis: Contracts iris dilator

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

Management of refractiveerrors

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

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.

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

Exotropia

Types Optical correction

Intermittent XT Mild to moderate hyperopia: not corrected

High hyperopia: FOC

Myopia: FOC/overminus

Pediatric Eye Evaluations Preferred Practice Pattern, 2012

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

Cooperated patients (8 years or older)

Without strabismus

Consistent BCVA

Indications

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

Asthenopia• Subjective symptoms of:– ocular fatigue – discomfort– headache arising from eyes

• Etiology:– Accomodative asthenopia– Muscular asthenopia– Nervous asthenopia

+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

+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.

+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.

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

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.

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)

the CLEAREST and the MOST COMFORTABLE

vision