StrabismusStrabismus

Refractive errorsRefractive errors

AmblyopiaAmblyopia

StrabismusStrabismus

= Squint = Squint

- Misalignment of the eyes(fovea of one Misalignment of the eyes(fovea of one eye fixates at the target & and fovea eye fixates at the target & and fovea of the other eye is off the target)of the other eye is off the target)

- affects~5% of the population- affects~5% of the population

Anatomy of extra ocular Anatomy of extra ocular musclesmuscles--Six extra-ocular muscles in each Six extra-ocular muscles in each

eye(responsible for eye movements)eye(responsible for eye movements) - Four rectus (straight) :- Superior rectus- Four rectus (straight) :- Superior rectus - Inferior rectus- Inferior rectus - Medial rectus- Medial rectus - Lateral rectus- Lateral rectus - Two oblique:- - Superior Oblique- Two oblique:- - Superior Oblique - Inferior Oblique- Inferior Oblique

Cont…Cont…

Rectus muscles:-Rectus muscles:- - - Origin:-Origin:-common annular tendon of common annular tendon of

Zinn, Zinn, around the optic foramen.around the optic foramen. - - Insertion:-Insertion:-sclera,various distances fromsclera,various distances from the limbusthe limbus - - Blood Supply:-Blood Supply:- muscular branches of muscular branches of

thethe ophthalmic arteryophthalmic artery

Cont…Cont…Innervation : - IIICNInnervation : - IIICN = - Medial Rectus = - Medial Rectus

- Inferior rectus- Inferior rectus

- Superior rectus- Superior rectus

- Inferior oblique- Inferior oblique

-IV CN-IV CN = Superior oblique = Superior oblique

-VI CN-VI CN = Lateral Rectus = Lateral Rectus

Actions of the rectus Actions of the rectus musclesmuscles LR LR = abduction = abduction

MR MR = adduction= adduction

SRSR = elevation, intorsion and = elevation, intorsion and adductionadduction

IR IR = depression, extorsion and = depression, extorsion and adductionadduction

Oblique MusclesOblique Muscles Inferior oblique:-Inferior oblique:-

- - originorigin:-inner end of the inferior orbital rim:-inner end of the inferior orbital rim

- - insertioninsertion:- outer part of the sclera behind:- outer part of the sclera behind the equator, around the maculathe equator, around the macula - - Action Action :- Extortion, elevation and abduction:- Extortion, elevation and abduction

Cont…Cont… Superior ObliqueSuperior Oblique

OOriginrigin:- upper and inner margin of optic :- upper and inner margin of optic foramenforamen InsertionInsertion:-posterior to equator-supero-:-posterior to equator-supero-

temporal temporal quadrantquadrant ( after passing through TROCHLEA)( after passing through TROCHLEA) Action Action :- intorsion, depression and abduction:- intorsion, depression and abduction

StrabismusStrabismus

- Strabismus Strabismus = a Latin word for = a Latin word for squintsquint- Squint= Squint= eyes are looking in different eyes are looking in different

directiondirection- Many possible causes for a squint to Many possible causes for a squint to

develop=>a cause should be looked develop=>a cause should be looked forfor

- For a squint to develop, For a squint to develop, Binocular Binocular reflexesreflexes should fail. should fail.

Binocular ReflexesBinocular Reflexes

Involve Involve SensorySensory and and Motor Motor partsparts SensorySensory:- takes two images produced by :- takes two images produced by

the two eyes and joins them together in the two eyes and joins them together in the brain.the brain.

MotorMotor:-the two eyes always move :-the two eyes always move together, so that they are always pointing together, so that they are always pointing in the same direction in the same direction

The binocular reflexes are much weaker in The binocular reflexes are much weaker in children, and there fore squints usually children, and there fore squints usually start in early childhoodstart in early childhood

Cont…Cont…

Disorders of vision affect Disorders of vision affect SensorySensory part of the part of the reflexreflex

-no stimulus from the diseased eye to-no stimulus from the diseased eye to remain pointing in the same direction remain pointing in the same direction as the healthy eye, so the diseased eye as the healthy eye, so the diseased eye develops a squintdevelops a squint e.g -corneal scare.g -corneal scar -cataract-cataract -retina/optic nerve lesion-retina/optic nerve lesion

Cont…Cont…

Disorders of the eye movements affect the Disorders of the eye movements affect the motor part of the reflexmotor part of the reflex

- - Extra ocular musclesExtra ocular muscles -Congenital abnormalities-Congenital abnormalities -Fractures of the orbital walls-Fractures of the orbital walls -Dysthyriod eye diseases-Dysthyriod eye diseases -Diseases of the EOM(e.g.myopathy)-Diseases of the EOM(e.g.myopathy) - - Cranial NervesCranial Nerves -Paralysis-Paralysis

Strabismus Cont…Strabismus Cont… Phoria:-Phoria:- a latent deviation where there is a latent deviation where there is

an underlying tendency for thean underlying tendency for the

eyes to drift aparteyes to drift apart

- held in alignment by motor fusion- held in alignment by motor fusion Intermittent tropia:-Intermittent tropia:-

-a latent deviation becomes -a latent deviation becomes manifestmanifest

when fusion brakes at timeswhen fusion brakes at times Tropia:-Tropia:-strabismus is manifeststrabismus is manifest

Bruckner test=Red reflex Bruckner test=Red reflex testtest=Illumination test=Illumination test Part of routine pediatric ophthalmology Part of routine pediatric ophthalmology

examinationexamination Uses direct ophthalmoscopeUses direct ophthalmoscope In a dim room the observer views In a dim room the observer views

through the ophthalmoscope from a through the ophthalmoscope from a distance of ~ 1 meter.distance of ~ 1 meter.

Assesses the Assesses the RED REFLEXESRED REFLEXES in both in both eyes eyes SIMULTANEOUSLYSIMULTANEOUSLY- should - should appear appear BRIGHT BRIGHT and and EQUALEQUAL in both in both eyeseyes

Problems which can be Problems which can be identified by Brückner-identified by Brückner-test:test:1.1. SquintSquint

2.2. AnisometropiaAnisometropia

3.3. Opacities within the optical Opacities within the optical media ( cornea,lens,vitreous) media ( cornea,lens,vitreous)

4.4. Changes of the fundus Changes of the fundus (Coloboma, RBL) (Coloboma, RBL)

Bruckner test cont…Bruckner test cont…

Brighter reflex :-StrabismusBrighter reflex :-Strabismus Dimmer reflex :- AmetropiaDimmer reflex :- Ametropia

-Media opacity-Media opacity

N.B.: Strabismic angles N.B.: Strabismic angles as small as 1° are as small as 1° are detectable!detectable!

Strabismus cont…Strabismus cont… Esotropia:-Esotropia:- inward deviation inward deviation

Exotropia:-Exotropia:- outward deviation outward deviation

Hypertropia:-Hypertropia:- upward deviation upward deviation

Hypotropia:-Hypotropia:- downward deviation downward deviation

EsotropiaEsotropia Inward turning of the eyeInward turning of the eye The most common form of childhood The most common form of childhood

strabismusstrabismus Usually associated with hyperopiaUsually associated with hyperopia Types:-congenitalTypes:-congenital -Acquired:-Accommodative-Acquired:-Accommodative -Nonaccommodative-Nonaccommodative -Incomitant e.g VI -Incomitant e.g VI

nerve palsynerve palsy

Management of EsotropiaManagement of Esotropia

Convex (+) glassesConvex (+) glasses

Accommodative esotropiaAccommodative esotropia SurgerySurgery

- Congenital Esotropia- Congenital Esotropia

- Acquired nonaccommodative - Acquired nonaccommodative esotropiaesotropia

- Paralytic esotrpia- Paralytic esotrpia ParasympathomimeticsParasympathomimetics

ExotropiaExotropia Outward deviation of the eyeOutward deviation of the eye

Types:-Types:-

- Congenital- Congenital

- Acquired - nonparalytic- Acquired - nonparalytic

- paralytic e.g III - paralytic e.g III nerve palsynerve palsy

Management of ExotropiaManagement of Exotropia

NonsurgicalNonsurgical

Corrective glasses espe. Corrective glasses espe. MyopiaMyopia

Overminusing!Overminusing! SurgicalSurgical

Vertical StrabismusVertical Strabismus

Hypertropia, hypotropiaHypertropia, hypotropia Types:- Types:-

-Comitant:--Comitant:-

usually accompanies horizontalusually accompanies horizontal

strabismusstrabismus

-Incomitant - muscle restriction-Incomitant - muscle restriction

- paralytic e.g IV nerve - paralytic e.g IV nerve palsypalsy

Management of Vertical Management of Vertical strabismusstrabismus

Surgery!Surgery!

Management of Management of StrabismusStrabismus In children:-In children:- 1. Find the cause1. Find the cause 2. Correct refractive errors with spectacles2. Correct refractive errors with spectacles 3. Treat Amblyopia3. Treat Amblyopia 4. Straighten the eyes with surgery4. Straighten the eyes with surgery In adults:-In adults:-- If the squint started in childhood= cosmetic - If the squint started in childhood= cosmetic

surgerysurgery- If the squint is recent- If the squint is recent - look for a cause- look for a cause -wait 6 mons.before considering surgery-wait 6 mons.before considering surgery

Refractive ErrorsRefractive Errors

Refractive states of the Refractive states of the eyeeye Measured looking in the Measured looking in the

distance(usually 6mts) so that the distance(usually 6mts) so that the ciliary muscle is relaxed (that is ciliary muscle is relaxed (that is not accommodated)not accommodated)

EmmetropiaEmmetropia A normal conditionA normal condition Parallel rays of light from infinity Parallel rays of light from infinity

come to a focus on the come to a focus on the retina(fovea)retina(fovea)

=> no error of refraction/visual => no error of refraction/visual acuity is normalacuity is normal

AmetropiaAmetropia Abnormal condition/absence of Abnormal condition/absence of

emmetropiaemmetropia Parallel rays of light from infinity do not Parallel rays of light from infinity do not

come to a focus on the retina (fovea)come to a focus on the retina (fovea) =>error of refraction=>error of refraction * Myopia or short/Near-sightedness* Myopia or short/Near-sightedness * Hyperopia or long/Far-* Hyperopia or long/Far-

sightednesssightedness * Astigmatism* Astigmatism ** Presbyopia** Presbyopia

AnisometropiaAnisometropia

Unequal refractive power of the Unequal refractive power of the eyeseyes

e.g :-e.g :-

1.1. one eye emmetropic, the other one eye emmetropic, the other one myopicone myopic

2.2. OD;- 0, OS:- -3.0 DOD;- 0, OS:- -3.0 D

3.3. OD:- +1.5 D, OS:- +3.5 DOD:- +1.5 D, OS:- +3.5 D

Pinhole testPinhole test

Any patient with defective visual Any patient with defective visual acuity should be tested again acuity should be tested again with a pinholewith a pinhole

If visual acuity improves with pin If visual acuity improves with pin hole=> refractive errorhole=> refractive error

If no improvement=>the loss of If no improvement=>the loss of vision is from eye diseasevision is from eye disease

Ametropia cont…Ametropia cont… Axial ametropia:-Axial ametropia:-

- the eye ball is either unusually long- the eye ball is either unusually long

(Myopia)or short(Hyperopia)(Myopia)or short(Hyperopia) Refractive ametropia:-Refractive ametropia:-

-The length of the eye is normal-The length of the eye is normal

- Excessive power in myopia, inadequate - Excessive power in myopia, inadequate

in hyperopiain hyperopia

e.g of extreme refractive e.g of extreme refractive hyperopia=Aphakiahyperopia=Aphakia

Myopia=Short-Myopia=Short-sightednesssightedness Short-sightednessShort-sightedness A condition where the light rays from a A condition where the light rays from a

distance object are focused in front of the distance object are focused in front of the retina.retina.

There fore the image at the retina is There fore the image at the retina is blurred and the vision is poor for distance blurred and the vision is poor for distance objects, but good objects, but good

for near objects.for near objects. The greater the degree of myopia, the The greater the degree of myopia, the

closer the patient has to hold things to see closer the patient has to hold things to see them clearly without any spectaclesthem clearly without any spectacles

Treatment of myopiaTreatment of myopia Concave(-) spherical glassesConcave(-) spherical glasses Contact lenses(concave)Contact lenses(concave) Laser surgeryLaser surgery

Hyperopia/HypermetropiaHyperopia/Hypermetropia=long-sightedness=long-sightedness An error of refraction in which parallel An error of refraction in which parallel

rays of light from infinity come to a rays of light from infinity come to a focus behind the retina, so they are focus behind the retina, so they are blurred at the retina.blurred at the retina.

Visual acuity is decreased except for Visual acuity is decreased except for young people who can use their young people who can use their accommodation to focus on the retina.accommodation to focus on the retina.

With age the power of accommodation With age the power of accommodation decreases.decreases.

Symptoms of HyperopiaSymptoms of Hyperopia Blurring of near visionBlurring of near vision Not much compliant regarding Not much compliant regarding

distance vision, as distance vision distance vision, as distance vision does not need accommodation does not need accommodation that much. that much.

Headache due to constant strain Headache due to constant strain on accommodationon accommodation

TreatmentTreatment Convex (+)spherical glassesConvex (+)spherical glasses Convex contact lensesConvex contact lenses Laser surgeryLaser surgery

AstigmatismAstigmatism The eye has a different focus in The eye has a different focus in

different planesdifferent planes An error of refraction in which the An error of refraction in which the

parallel rays of light from infinity parallel rays of light from infinity cannot converge to a point focus cannot converge to a point focus due to unequal refraction in due to unequal refraction in different meridians of the optical different meridians of the optical focus of the eye.focus of the eye.

Causes of astigmatismCauses of astigmatism

a.a. Unequal curvature of the cornea or Unequal curvature of the cornea or lens in different meridians, so that lens in different meridians, so that the refractive surfaces are not the refractive surfaces are not spherical.spherical.

b.b. Decentering of the lens due to slight Decentering of the lens due to slight shifting in position or tilting of the shifting in position or tilting of the lens as occurs in subluxation.lens as occurs in subluxation.

Symptoms of astigmatismSymptoms of astigmatism

Diminished visual acuityDiminished visual acuity Headache due to exertion of Headache due to exertion of

accommodation to rectify the accommodation to rectify the defect particularly in defect particularly in hypermetropic astigmatismhypermetropic astigmatism

TreatmentTreatment Cylindrical lensesCylindrical lenses

-spectacles-spectacles

-contact lenses-contact lenses Laser surgeryLaser surgery

PresbyopiaPresbyopia Usually becomes age beyond 40 yearsUsually becomes age beyond 40 years Part of the natural ageing process in the Part of the natural ageing process in the

lenslens With age lens becomes harder=>loss of With age lens becomes harder=>loss of

elasticity of the lens=>loss of elasticity of the lens=>loss of accommodative response accommodative response

The eye can still see distant objects The eye can still see distant objects clearly, but cannot focus on near clearly, but cannot focus on near objects.objects.

Symptoms of PresbyopiaSymptoms of Presbyopia

Blurring of vision while reading Blurring of vision while reading books/carry out near- vision books/carry out near- vision tasks.tasks.

Vision improves if the object is Vision improves if the object is held further away from the eye.held further away from the eye.

Those doing close work feel the Those doing close work feel the symptoms earlier.symptoms earlier.

Treatment of presbyopiaTreatment of presbyopia

Convex spherical lenses, which is Convex spherical lenses, which is added on glasses if any for added on glasses if any for distant vision.distant vision.

AmblyopiaAmblyopia

=>Poor vision caused by abnormal =>Poor vision caused by abnormal visual experience early in life. (i.e. visual experience early in life. (i.e. in the immature visual system)in the immature visual system)

Visual development…Visual development… Continues until 7/8 yearsContinues until 7/8 years Latent period in first 6/52 of lifeLatent period in first 6/52 of life Followed by critical or sensitive Followed by critical or sensitive

periodperiod Affected by disease/visual Affected by disease/visual

deprivation in sensitive perioddeprivation in sensitive period

Cont…Cont… Amblyopia=a greek termAmblyopia=a greek term

amblyos=dull/blunt, Opia=visionamblyos=dull/blunt, Opia=vision

Occurs in 2-4% of the general Occurs in 2-4% of the general populationpopulation

The most common cause of decreased The most common cause of decreased vision in childhood(birth-7/8 yrs.)vision in childhood(birth-7/8 yrs.)

Definition of amblyopiaDefinition of amblyopia A unilateral/bilateral reduction of best A unilateral/bilateral reduction of best

corrected visual acuity that can’t be corrected visual acuity that can’t be attributed to the effect of any attributed to the effect of any structural abnormality of the eye or structural abnormality of the eye or posterior visual pathway.posterior visual pathway.

If best corrected vision in one eye is If best corrected vision in one eye is at least two lines worse in the snellen at least two lines worse in the snellen chart than the other eye or a vision of chart than the other eye or a vision of 6/12 or worse in both eyes6/12 or worse in both eyes

PathophysiologyPathophysiologyi.i. Abnormal binocular interactionAbnormal binocular interaction

ii.ii. Retinal image blurRetinal image blur

iii.iii. BothBoth

Three “D”sThree “D”s

i.i. Deviated i.e strabismusDeviated i.e strabismus

ii.ii. Defocused i.e anisometropia, ametropiaDefocused i.e anisometropia, ametropia

iii.iii. Deprived e.g. cataract,corneal Deprived e.g. cataract,corneal opacity,etcopacity,etc

ManagementManagement

One of the most time One of the most time consuming tasks in pediatric consuming tasks in pediatric ophthalmology ,but if ophthalmology ,but if successful it is one of the successful it is one of the most rewarding!most rewarding!

Cont…Cont… Basic Strategies:-Basic Strategies:-

1.1. Provide a clear retinal imageProvide a clear retinal image

2.2. Correct ocular dominanceCorrect ocular dominance

Cont…Cont…1.1. Occlusion:-Occlusion:-

-”gold standard”-”gold standard”

- priciple:- cover the sound eye to - priciple:- cover the sound eye to force the poor seeing eye to see better force the poor seeing eye to see better

2. Penalization(optical/pharmacologic):-2. Penalization(optical/pharmacologic):-

Blurring of the sound eye to forceBlurring of the sound eye to force

fixation with the amblyopic eye.fixation with the amblyopic eye.