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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
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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
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TYPES OF PEDIATRIC REFRACTION
SUBJECTIVE REFRACTION WITH/WITHOUT CYCLOPLEGIGS
OBJECTIVE REFRACTION
STATIC and NEAR
RETINOSCOPYDYANAMIC
MANIFEST
CYCLOPLEGICS
MEM BELL BOOK CHROMORETINOSCOPY
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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
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CYCLOPLEGIC REFRACTION CYCLOPLEGICS are the drugs that paralyze
the ciliary muscles resulting in loss of accommodation and secondarily dilatation of Pupil
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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
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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)
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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
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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
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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
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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
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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.
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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
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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
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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
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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
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RETINOSCOPY Objective means of obtaining Refractive error
PRINCIPLE
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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
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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
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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
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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
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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.
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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
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DYNAMIC RETINOSCO
PY
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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