3.refractive error, strabismus, ambylopia

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3.refractive error, strabismus, ambylopia

  1. 1.  StrabismusStrabismus Refractive errorsRefractive errors AmblyopiaAmblyopia
  2. 2. StrabismusStrabismus = Squint= Squint - Misalignment of the eyes(fovea of one eyeMisalignment of the eyes(fovea of one eye fixates at the target & and fovea of the otherfixates at the target & and fovea of the other eye is off the target)eye is off the target) - affects~5% of the population- affects~5% of the population
  3. 3. Anatomy of extra ocularAnatomy of extra ocular musclesmuscles --Six extra-ocular muscles in eachSix 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
  4. 4. Cont…Cont… Rectus muscles:-Rectus muscles:- -- Origin:-Origin:-common annular tendon of Zinn,common annular tendon of 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 themuscular branches of the ophthalmic arteryophthalmic artery
  5. 5. 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= Superior obliqueoblique -VI CN-VI CN = Lateral= Lateral RectusRectus
  6. 6. Actions of the rectus musclesActions of the rectus muscles  LRLR = abduction= abduction  MRMR = adduction= adduction  SRSR = elevation, intorsion and adduction= elevation, intorsion and adduction  IRIR = depression, extorsion and adduction= depression, extorsion and adduction
  7. 7. 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 -- ActionAction :- Extortion, elevation and abduction:- Extortion, elevation and abduction
  8. 8. Cont…Cont…  Superior ObliqueSuperior Oblique OOriginrigin:- upper and inner margin of optic:- upper and inner margin of optic foramenforamen InsertionInsertion:-posterior to equator-supero-temporal:-posterior to equator-supero-temporal quadrantquadrant ( after passing through TROCHLEA)( after passing through TROCHLEA) ActionAction :- intorsion, depression and abduction:- intorsion, depression and abduction
  9. 9. StrabismusStrabismus - StrabismusStrabismus = a Latin word for= a Latin word for squintsquint - Squint=Squint= eyes are looking in differenteyes are looking in different directiondirection - Many possible causes for a squint toMany possible causes for a squint to develop=>a cause should be lookeddevelop=>a cause should be looked forfor - For a squint to develop,For a squint to develop, BinocularBinocular reflexesreflexes should fail.should fail.
  10. 10. Binocular ReflexesBinocular Reflexes  InvolveInvolve SensorySensory andand MotorMotor partsparts  SensorySensory:- takes two images produced by:- takes two images produced by the two eyes and joins them together in thethe two eyes and joins them together in the brain.brain.  MotorMotor:-the two eyes always move together,:-the two eyes always move together, so that they are always pointing in the sameso that they are always pointing in the same directiondirection  The binocular reflexes are much weaker inThe binocular reflexes are much weaker in children, and there fore squints usually startchildren, and there fore squints usually start in early childhoodin early childhood
  11. 11. Cont…Cont…  Disorders of vision affectDisorders of vision affect SensorySensory part of thepart of the reflexreflex -no stimulus from the diseased eye to-no stimulus from the diseased eye to remain pointing in the same directionremain pointing in the same direction as the healthy eye, so the diseased eyeas 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
  12. 12. Cont…Cont…  Disorders of the eye movements affect theDisorders 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
  13. 13. Strabismus Cont…Strabismus Cont…  Phoria:-Phoria:- a latent deviation where there isa 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 manifest-a latent deviation becomes manifest when fusion brakes at timeswhen fusion brakes at times  Tropia:-Tropia:-strabismus is manifeststrabismus is manifest
  14. 14. Bruckner test=Red reflex testBruckner test=Red reflex test =Illumination test=Illumination test  Part of routine pediatric ophthalmologyPart of routine pediatric ophthalmology examinationexamination  Uses direct ophthalmoscopeUses direct ophthalmoscope  In a dim room the observer views throughIn a dim room the observer views through the ophthalmoscope from a distance of ~ 1the ophthalmoscope from a distance of ~ 1 meter.meter.  Assesses theAssesses the RED REFLEXESRED REFLEXES in bothin both eyeseyes SIMULTANEOUSLYSIMULTANEOUSLY- should appear- should appear BRIGHTBRIGHT andand EQUALEQUAL in both eyesin both eyes
  15. 15. Problems which can beProblems which can be identified by Brückner-test:identified by Brückner-test: 1.1. SquintSquint 2.2. AnisometropiaAnisometropia 3.3. Opacities within the optical mediaOpacities within the optical media ( cornea,lens,vitreous)( cornea,lens,vitreous) 4.4. Changes of the fundus (Coloboma,Changes of the fundus (Coloboma, RBL)RBL)
  16. 16. Bruckner test cont…Bruckner test cont…  Brighter reflex :-StrabismusBrighter reflex :-Strabismus  Dimmer reflex :- AmetropiaDimmer reflex :- Ametropia -Media opacity-Media opacity
  17. 17. N.B.: Strabismic anglesN.B.: Strabismic angles as small as 1° areas small as 1° are detectable!detectable!
  18. 18. Strabismus cont…Strabismus cont…  Esotropia:-Esotropia:- inward deviationinward deviation  Exotropia:-Exotropia:- outward deviationoutward deviation  Hypertropia:-Hypertropia:- upward deviationupward deviation  Hypotropia:-Hypotropia:- downward deviationdownward deviation
  19. 19. EsotropiaEsotropia  Inward turning of the eyeInward turning of the eye  The most common form of childhoodThe 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 nerve-Incomitant e.g VI nerve palsypalsy
  20. 20. 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
  21. 21. ExotropiaExotropia  Outward deviation of the eyeOutward deviation of the eye  Types:-Types:- - Congenital- Congenital - Acquired - nonparalytic- Acquired - nonparalytic - paralytic e.g III nerve- paralytic e.g III nerve palsypalsy
  22. 22. Management of ExotropiaManagement of Exotropia  NonsurgicalNonsurgical Corrective glasses espe. MyopiaCorrective glasses espe. Myopia Overminusing!Overminusing!  SurgicalSurgical
  23. 23. 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 palsy- paralytic e.g IV nerve palsy
  24. 24. Management of VerticalManagement of Vertical strabismusstrabismus Surgery!Surgery!
  25. 25. Management of StrabismusManagement of Strabismus  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 surgery- If the squint started in childhood= cosmetic surgery - 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
  26. 26. Refractive ErrorsRefractive Errors
  27. 27. Refractive states of the eyeRefractive states of the eye  Measured looking in theMeasured looking in the distance(usually 6mts) so that thedistance(usually 6mts) so that the ciliary muscle is relaxed (that is notciliary muscle is relaxed (that is not accommodated)accommodated)
  28. 28. EmmetropiaEmmetropia  A normal conditionA normal condition  Parallel rays of light from infinity comeParallel rays of light from infinity come to a focus on the retina(fovea)to a focus on the retina(fovea) => no error of refraction/visual acuity is=> no error of refraction/visual acuity is normalnormal
  29. 29. AmetropiaAmetropia  Abnormal condition/absence of emmetropiaAbnormal condition/absence of emmetropia  Parallel rays of light from infinity do notParallel 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-sightedness* Hyperopia or long/Far-sightedness * Astigmatism* Astigmatism ** Presbyopia** Presbyopia
  30. 30. AnisometropiaAnisometropia  Unequal refractive power of the eyesUnequal refractive power of the eyes e.g :-e.g :- 1.1. one eye emmetropic, the other oneone eye emmetropic, the other one myopicmyopic 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
  31. 31. Pinhole testPinhole test  Any patient with defective visual acuityAny patient with defective visual acuity should be tested again with a pinholeshould be tested again with a pinhole  If visual acuity improves with pinIf visual acuity improves with pin hole=> refractive errorhole=> refractive error  If no improvement=>the loss of visionIf no improvement=>the loss of vision is from eye diseaseis from eye disease
  32. 32. 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 refractivee.g of extreme refractive hyperopia=Aphakiahyperopia=Aphakia
  33. 33. Myopia=Short-sightednessMyopia=Short-sightedness  Short-sightednessShort-sightedness  A condition where the light rays from aA condition where the light rays from a distance object are focused in front of thedistance object are focused in front of the retina.retina.  There fore the image at the retina is blurredThere fore the image at the retina is blurred and the vision is poor for distance objects,and the vision is poor for distance objects, but goodbut good for near objects.for near objects.  The greater the degree of myopia, theThe greater the degree of myopia, the closer the patient has to hold things to seecloser the patient has to hold things to see them clearly without any spectaclesthem clearly without any spectacles
  34. 34. Treatment of myopiaTreatment of myopia  Concave(-) spherical glassesConcave(-) spherical glasses  Contact lenses(concave)Contact lenses(concave)  Laser surgeryLaser surgery
  35. 35. Hyperopia/HypermetropiaHyperopia/Hypermetropia =long-sightedness=long-sightedness  An error of refraction in which parallelAn error of refraction in which parallel rays of light from infinity come to arays of light from infinity come to a focus behind the retina, so they arefocus behind the retina, so they are blurred at the retina.blurred at the retina.  Visual acuity is decreased except forVisual acuity is decreased except for young people who can use theiryoung people who can use their accommodation to focus on the retina.accommodation to focus on the retina.  With age the power of accommodationWith age the power of accommodation decreases.decreases.
  36. 36. Symptoms of HyperopiaSymptoms of Hyperopia  Blurring of near visionBlurring of near vision  Not much compliant regardingNot much compliant regarding distance vision, as distance visiondistance vision, as distance vision does not need accommodation thatdoes not need accommodation that much.much.  Headache due to constant strain onHeadache due to constant strain on accommodationaccommodation
  37. 37. TreatmentTreatment  Convex (+)spherical glassesConvex (+)spherical glasses  Convex contact lensesConvex contact lenses  Laser surgeryLaser surgery
  38. 38. AstigmatismAstigmatism  The eye has a different focus inThe eye has a different focus in different planesdifferent planes  An error of refraction in which theAn error of refraction in which the parallel rays of light from infinityparallel rays of light from infinity cannot converge to a point focus duecannot converge to a point focus due to unequal refraction in differentto unequal refraction in different meridians of the optical focus of themeridians of the optical focus of the eye.eye.
  39. 39. Causes of astigmatismCauses of astigmatism a.a. Unequal curvature of the cornea orUnequal curvature of the cornea or lens in different meridians, so thatlens in different meridians, so that the refractive surfaces are notthe refractive surfaces are not spherical.spherical. b.b. Decentering of the lens due to slightDecentering of the lens due to slight shifting in position or tilting of theshifting in position or tilting of the lens as occurs in subluxation.lens as occurs in subluxation.
  40. 40. Symptoms of astigmatismSymptoms of astigmatism  Diminished visual acuityDiminished visual acuity  Headache due to exertion ofHeadache due to exertion of accommodation to rectify the defectaccommodation to rectify the defect particularly in hypermetropicparticularly in hypermetropic astigmatismastigmatism
  41. 41. TreatmentTreatment  Cylindrical lensesCylindrical lenses -spectacles-spectacles -contact lenses-contact lenses  Laser surgeryLaser surgery
  42. 42. PresbyopiaPresbyopia  Usually becomes age beyond 40Usually becomes age beyond 40 yearsyears  Part of the natural ageing process inPart of the natural ageing process in the lensthe lens  With age lens becomes harder=>lossWith age lens becomes harder=>loss of elasticity of the lens=>loss ofof elasticity of the lens=>loss of accommodative responseaccommodative response  The eye can still see distant objectsThe eye can still see distant objects clearly, but cannot focus on nearclearly, but cannot focus on near
  43. 43. Symptoms of PresbyopiaSymptoms of Presbyopia  Blurring of vision while readingBlurring of vision while reading books/carry out near- vision tasks.books/carry out near- vision tasks.  Vision improves if the object is heldVision improves if the object is held further away from the eye.further away from the eye.  Those doing close work feel theThose doing close work feel the symptoms earlier.symptoms earlier.
  44. 44. Treatment of presbyopiaTreatment of presbyopia  Convex spherical lenses, which isConvex spherical lenses, which is added on glasses if any for distantadded on glasses if any for distant vision.vision.
  45. 45. AmblyopiaAmblyopia =>Poor vision caused by abnormal=>Poor vision caused by abnormal visual experience early in life. (i.e. invisual experience early in life. (i.e. in the immature visual system)the immature visual system)
  46. 46. 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 periodFollowed by critical or sensitive period  Affected by disease/visual deprivationAffected by disease/visual deprivation in sensitive periodin sensitive period
  47. 47. Cont…Cont…  Amblyopia=a greek termAmblyopia=a greek term amblyos=dull/blunt, Opia=visionamblyos=dull/blunt, Opia=vision  Occurs in 2-4% of the generalOccurs in 2-4% of the general populationpopulation  The most common cause ofThe most common cause of decreased vision in childhood(birth-7/8decreased vision in childhood(birth-7/8 yrs.)
  48. 48. Definition of amblyopiaDefinition of amblyopia  A unilateral/bilateral reduction of bestA unilateral/bilateral reduction of best corrected visual acuity that can’t becorrected visual acuity that can’t be attributed to the effect of any structuralattributed to the effect of any structural abnormality of the eye or posteriorabnormality of the eye or posterior visual pathway.visual pathway.  If best corrected vision in one eye is atIf best corrected vision in one eye is at least two lines worse in the snellenleast two lines worse in the snellen chart than the other eye or a vision ofchart than the other eye or a vision of 6/12 or worse in both eyes6/12 or worse in both eyes
  49. 49. PathophysiologyPathophysiology i.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,cornealDeprived e.g. cataract,corneal opacity,etcopacity,etc
  50. 50. ManagementManagement  One of the most time consumingOne of the most time consuming tasks in pediatrictasks in pediatric ophthalmology ,but if successfulophthalmology ,but if successful it is one of the most rewarding!it is one of the most rewarding!
  51. 51. Cont…Cont…  Basic Strategies:-Basic Strategies:- 1.1. Provide a clear retinal imageProvide a clear retinal image 2.2. Correct ocular dominanceCorrect ocular dominance
  52. 52. Cont…Cont… 1.1. Occlusion:-Occlusion:- -”gold standard”-”gold standard” - priciple:- cover the sound eye to force- priciple:- cover the sound eye to force the poor seeing eye to see betterthe poor seeing eye to see better 2.2. Penalization(optical/pharmacologic)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.
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