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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.