1

PEDIATRIC REFRACTION

YASHASWEE BHATTARAIBOPTOM 3RD YEAR BVDUMC SCHOOL OF OPTOMETRYyashaswee.bhattarai@yahoo.com

2

HOW IS IT DIFFERENT FROM NORMAL REFRACTION??????

Objective Refraction is usually used to determine refractive status of infants and preverbal children

Meticulously and accurately done

Great expertise is necessary

Should understand Emmetropization and relation between state of BSV and refractive status of child

Techniques must be easily understandable

Cycloplegic Refraction is preferable due to active accomodation in child

3

REFRACTIVE STATUS OF CHILDREN

FIRST YEAR OF LIFE 3-5 YEARS OLD ADOLESCENCE

•SPHERICAL REFRACTIONHealthy neonates are hyperopic (+2.00 D)

•PREMATURE NEWBORNSBirth weight <2500gm= -1 to -10 D (-4.00 D) mostly myopic and can become emmetropic as age increases

Some hyperopic (+5D)

•ASTIGMATISMUncommonSometime +1 D present

•ANISOMETROPIA

•Length of Globe increases (5mm from birth to 3 yrs)•Process of emmetropization during 1st yr of life

•SPHERICAL REFRACTION

•ASTIGMATISM

•ANISOMETROPIA

•Mostlly emmetropic•More myopic than hyperopic

•If myopic at 5-6 yrs= >myopia

•>+1.50D hyperopic at 5-6yrs = mild hyperopic at 13 -14 yrs

•Spherical Refraction +0.50D to +1.00D = emmetropic at 13-14yrs

•Spherical Refraction 0.00D - +0.50= myopic by 13-14 yrs

•NB- AS AGE INCREASES SIZE OF EYE INCEREASES

4

TYPES OF PEDIATRIC REFRACTION

SUBJECTIVE REFRACTION WITH/WITHOUT CYCLOPLEGIGS

OBJECTIVE REFRACTION

STATIC and NEAR

RETINOSCOPYDYANAMIC

MANIFEST

CYCLOPLEGICS

MEM BELL BOOK CHROMORETINOSCOPY

5

CHOICE OF REFRACTION FOR DIFFERENT AGE GROUPS

INFANTS

PRE-SCHOOL

SCHOOL AGED

Mohindra Near RetinoscopyRetinoscopy with and without cycloplegicsPhotorefraction

Keratometry/Placido’s disc/KeratoscopeRetinoscopy with or without cycloplegicsDistance (by showing TV for fixation)Dyanamic- MEM for NearBook RetinoscopySubjective Refraction

KeratometryManifest/Cycloplegic RetinoscopyDynamic RetinoscopySubjective Refraction

FUNDUS EVALUATION IN ALL

6

CYCLOPLEGIC REFRACTION CYCLOPLEGICS are the drugs that paralyze

the ciliary muscles resulting in loss of accommodation and secondarily dilatation of Pupil

7

WHY CYCLOPLEGIC REFRACTION?? To stop eye’s ability to auto focus or

accommodate in order to determine true prescription

When the eye contracts and relaxes the lens changes its shape

Cycloplegics paralyses ciliary muscles and lens can nolonger change its shape and there is no chance of accommodation

In children they have the great ability to vary their accommodation

8

HYPERMETROPIA

LATENTCorrecte

d by tone of ciliary muscle(cyclopl

egic refractio

n)

MANIFEST

A)FACULTATIVE

(Corrected by

accommodation)B)ABSOLUTE (Not corrected

by accommodation)

TOTAL Found out by

abolishing tone of

ciliary muscle

( cycloplegics)

9

MECHANISM OF ACTION Releases acetyl cholin from post

ganglionic nerve fibers

Parasympathetic

system

Blocks muscarine receptors in ciliary body

Ciliary body is paralysed

Loss of accommoda

tion

Parasympathetic supplies

Sphincter pupilary muscle

Dosent work

Pupil Dilates

10

Visual Acuity(Near/

Distance)

Pupillary Reflex and size under

roomillumination

Manifest Refractio

n

HistoryMedicalAllergic

Emotional

Hyperemia in

conjunctiva

Accommodation and

Binocular status

AC/A Relation

Ac angle and IOP

MEASUREMENTS TO BE DONE

BEFORE INSTILLING

CYCLOPLEGICS

11

IDEAL CYCLOPLEGICS SHOULD HAVE Rapid onset

Full Paralysis of accommodation

Sufficient duration to allow accurate assessment of refraction

Rapid recovery of accommodation

Dissociation from cycloplegic effect from mydriatic effect

Absence of local and systemic side effects Capacity of safe administration by appropriate person

12

CHOICE OF CYCLOPLEGICSNAME AGE CONCENTRAT

IONSTART OF EFFECT

DURATION

TONUS ALLOWANCE/RESIDUALACCOMMODATION

ATROPINE 0-7years

1% 1 drop- twice a day-3 days

Cycloplegic=30mins to 3 days

10-14days

PMT-14Days

TA= +1.5 DRA= 0

CYCLOPENTOLATE

7-15years

7-12yrs=1%12-15yr=0.5%1 drop15-20mins -2nd drop

Cycloplegics= few mins

Maximizes in 30-60mins

24-48hrs

PMT-2days

TA=+0.75D/0.5DRA= +1 D

HOMATROPINE 1-15years

1% 2% 5%2%- Common1 drop repeated twice after 10 mins )

starts in 15 mins

Maximizes in45-90 mins

24-48 hrs

PMT- 2 days

TA= +0.75DRA=+0.75D

TROPICAMIDEALL 0.5%, 1%

2 drops after 10 mins 4 drops total

Few minsMaximizes in 30 mins

6-8 hrs TA=0/<0.5 DRA=+1.5D

13

CHOICE OF CYCLOPLEGICS SCHOOL AGED CHILD

1% CYCLOPENTOLATE0.5% PROPARACAINE (Aid ocular absorption)

Let child rub eyes to facilitate absorption Children with dark iris pigmentation and

excessive body weight may require additional drop within 5 minutes to allow

cycloplegia.

14

According to the patients age we select the type of drug

Cyclopentolate is usual drug of choice although it is not as effective as atropine in inhibiting astigmatism because

a) Reasonabely powerful b)fast acting –produce cycloplegia within 45-90 mins and lose

effectiveness within 3-4 hrs c)relatively safe

Tropicamide is fast acting mydriatic but does not inhibit accomodation sufficiently to satisfy requirement of cycloplegic examination

Instill the selected cycloplegic according to the dosage

After refraction we get certain number of Refractive value

We deduct the tonus allowance

15

EG#1 For egIf 1% attropine is instilled in a child of 1 and half

years Retinoscopy is done at the distance of 1m

(example)

You get +5.00D = Gross Retinoscopiy value+5.00 D – 1.00 D = +4.00 D = Net Retinoscopy valueTonus allowance of atropine = +1.50D Resulting total Power = +4.00D - +1.5D = 2.50D

16

SIDE EFFECTS

ATROPINE

•Inhibits action of sweat and salivary gland leading to dryness•Tachycardia•Hallucination/Dizziness•Ataxia•Photophobia•Blurring of vision•Asthenopic symptoms

CYCLOPENTOLATE

•Less side effect•Photophobia•Blurring of vision•Burning sensation•Ataxia•Dizziness/Confusion•Tachycardia

HOMATROPINE

•Less severity than Atropine but same side effects•Its is just a derivative so doesn't paralyze ciliary muscles completely

TROPICAMIDE

• Only ocular side effects like

• Blurring of vision• Photophobia

• Burning sensation

17

18

ADVANTAGES OF CYCLOPLEGICS Used In cases of hyperopia, esotropia ,

convergence excess, accomodative spasm and when relative findings cannot be obtained in dry state

Helps in accurate refraction and post operative inflammation

Reliving pain in uveities Better view of fundus

DISADVANTAGES Poor vision and monochromatic abberation Accuracy is required

19

RETINOSCOPY Objective means of obtaining Refractive error

PRINCIPLE

20

NEAR RETINOSCOPY Not a variation of dynamic Retinoscopy

Basically a substitute for static Retinoscopy mainly used in infants

Done with/without cycloplegics

Studies showed the relative +5D underestimation of hyperopia in the procedure done without cycloplegics

Mohindra introduced a technique of non-cycloplegic retinoscopy that correlates somehow with cycloplegic findings

21

NEAR RETINOSCOPY DIFFERS FROM OTHER FORM OF DYANAMIC RETINOSCOPY IN 3 WAYS

1) It is performed in complete darkness, the only illumination in the room is supplied by retinoscope with child fixating at retinoscope light

2) It is monocular procedure i.e eye not being examined is occluded

3) The adjustment factor of -1.25D is algebrically combined with the spherical component of the gross sphero-cylindrical lens powers

22

PROCEDURE The examing room is darkened

Intensity of retinoscopy light is kept as minimum

Examiner encourages the child to fixate the light by making animal sounds

Examiner maintains the retinoscope at the distance of 50 cm from the infant

For young infants, the best way to scope are with the infants over parents shoulder or while the infant being fed

Lens racks are used to neutralize the retinoscopic motion

An adjustment value of -1.25D is algebrically added to the neutrality value to determine the distant refractive state

Eg- If the motion is neutral with +1.25D lens in place the infant is emmetropic

23

EG#2 Suppose we perform retinoscopy at 50cm Compensatory factor= +2D Average Lag of accommodation in infants

0.75D Total compensation= +2.00 – 0.75 D = +1.25

D Gross Retinoscopy value = +3.00 D Net Retinoscopy Value = +3.00- 1.25 D =

+1.75D

24

Wesson and colleagues (1990) suggested caution in substituting Mohindra retinoscopy for cycloplegic refraction using and adjustment value

They found significant difference between the two techniques in both sphere and cylinder power

Mohindra Retinoscopy is adequate for infants who do not have esophoria or esotropia

When either of these two exists , uncovering the full amount of latent hyperopia is imperative.

25

In 1977 extremely highly correlation between near and cycloplegic refraction was suggested

In study reported by Maino et al. (1984) results of Mohindra retinoscopy were not correlating with cycloplegic refraction

He stated that predictive value of near refraction was very low and concluded that it was not a good predictor of refractive error

It was not capable of identifying hyperopia of +3D or more or astigmatism of >1.00 D

Thus concluded that noncycloplegic refraction is not the alternative of cycloplegic standard refraction

26

DYNAMIC RETINOSCO

PY

27

Lead of accommodation- At distance closer than resting point amount of accommodation is less than that required by stimulus

Lag of accommodation- At distance beyond resting point amount of accommodation exceeds than that of required

DYNAMIC RETINOSCOPY - Objective test to measure the refractive status of the

eye

- Done at nearpoint (40cm) in order to determine how much plus power is required to achieve neutrality

- Basically used to measure lead and lag of accommodation

- Especially useful with young children, whom static retinoscopy is often not feasible.

- Number of ways have been proposed for carrying out dynamic retinoscopy.

The patient is asked to fixate at nearpoint stimulus/ plane of retinoscope

No working distance lens power is added or substracted

Examiner neutralizes the motion of the retinal reflex.

the retinal reflex is neutralized by using plus lenses

0.50D is deducted from the finding and the amount of plus lens power that must be added is patients lag of accomodation

And the remaining power will be the patient refractive error.

MONOCULAR ESTIMATION METHOD MEM is differ from standard dynamic retinoscopy in two

ways: - testing distance is not same for all patients - is the monocular procedure. testing distance is determined by the - physical size - preferred reading distance

YOUNG CHILDREN= 8-10 INCHES Though many clinicians choose “Harmon distance” (elbow to knuckle )as testing distance -The retinoscopy mirror is set at plano- The retinoscopy light or lens should not place infront of eye

more than 2 sec

The specific steps of procedure are:

1.Ask the patient to sit comfortably

2.Fixation target is a white card containing 1 and half inch hole having letters words or pictures according to child’s age.

3.It is printed within one and a half inch of the hole

4. The card is attached to the retinoscope with a clip

5. Retinoscope beam passes through the hole in the card

6. Examiner is seated on the stool slightly below patients eye level so the patients eye is at moderate downgaze while looking at the target

4. The patient Should wear his habitual prescription

5. The examiner takes a position of 10-16 inches from patient

6. The retinoscopy beam is directed toward the bridge of patient’s nose

Child is instructed to read the words aloud and examiner quickly moves his vertical streak across the pupil

7. with movement = lag of accommodation beyond the plane convergence

8. Examiner estimates the direction and approximate power of the reflex

9. Lens is placed in one eye to reassess the approximate power

10. If it validates the estimate lens power is recorded and if this does not then procedure is repeated with more appropritae lens

33

EG #3 With motion of moderate degree\ +0.50D lens in front of one eye If it neutralizes with motion +0.50D is

recorded If not +1.00D sphere is selected If neutral motion +1.00 is recorded If against motion 0.75D is recorded Normal +0.50D to +0.75D When lag more than +1.00 D prescribe plus

lens for near work

BOOK RETINOSCOPY Is the variation of dynamic retinoscopy

Patients fixates on a near-situated, accommodation-stimulating target

Differ from standard dynamic retinoscopy procedure in following way:

- where the fixation target is positioned. - what the examiner observes & - how these observations are interpreted

The procedure consists of 3 retinoscopic observation made at a distance of

- 15 feets - 7 feets - 20 inches with fixation target in each

distance

Target is placed at 20 inches for the children who could read

The target is book with picture so called as book retinoscopy

The goal of the procedure were to look for & record

relative brightness of reflex, ranging from dull to bright

color of the reflex , ranging from dull red to white

Speed, range, promptness, pick up & release motion

Meridional difference. Basically observes accomodative state of eye

37

INTERPRETATIONREFLEX BRIGHTNESS/ MOVEMENT

ATTENTION

INCREASED BRIGHTNESS/ Bright reflex

Moment when child identifies the target

With movement Child’s eye located the targetAgainst Movement Settled Attention and held to target

Occilation of against to with to against

Relaxed attention

Dull reflex Withdrew attention

THE REFLEX ON THE BASIS OF COLOUR ARE Dull Red, Dull Pink , Bright Pink, White Pink and Pink

BELL RETINOSCOPY The distance between patients &the examiner is 50 cm

Target is moving & the examiner is constant

The ball is used for the patient attraction

target should be interesting enough and suspended on its handle at eye level.

No lenses are used

If the initial reflex shows “neutral” or “with” motion, move the target (nt the retinoscope) towards the

patients, until against motion is seen and come back until neutral motion is observed in each principal meridian

Neutrality usually occurs when the ball is located about 15-16 inches from the patients face (37cm to 40 cm) resulting in lag of accomodation from 0.50 to 0.75D

If the initial reflex shows “against” motion the patients may judge to be over accommodation

record the distance between the target and the patient when against motion is seen as the target is pushing toward the patients

Interpretation If against motion seen between 15-18 inches, patient is

normal

If “with” motion seen between 15-18 inches, patients is normal

If delayed shift to against motion indicates latent , need for addition plus

Always with indicates, needs plus for near Always against motion – myopia If astigmatic reflex – indicates astigmatism

41

OPHTHAMOSCOPY Is also effective way to obtaining an objective

refractive finding The procedure itself is self-evident Simply determine the lens power to focus

the fundus. This will be refractive status of the patients.

43

SUBJECTIVE REFRACTION DONE WITH/WITHOUT CYCLOPLEGICS

44

THANK YOUREFERENCECLINICAL PEDIATRIC OPTOMETRYLeonardo J Press, OD, F.A.A.OBruce D. Moore, OD, F.A.A.O

Pediatric Optometry second editionJerome Rosner and Joy Rosner

Primary Care OptometryTheodore Grosvenor, OD, Ph.D, F.A.A.O

Optometric InvestigationsDavid. B. Henson. Msc Phd . F.A.A.O