Gede Pardianto - Strabismus, binocular vision, 3D vision and visual illusion

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Strabismus, binocular vision, 3D vision and visual illusion

Dr. Gede Pardianto.
SMEC Jakarta Jl Pemuda 36 Rawamangun Jakarta Timur.
Sumatera Eye Center Jl Iskandar Muda 278 Medan.
Tel 628155000300.

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Gede Pardianto - Strabismus, binocular vision, 3D vision and visual illusion

  1. 1. Strabismus and the Binocular Single Vision
  2. 2. The information provided within this lecture is for educational and scientific purposes only and it should not be construed as commercial advice. Author thanks all of our teachers, fellow ophthalmologists, publishers, sponsors, and all manufacturers for their works those all being cited in this handout. FREE COPY NOT FOR SALE 2
  3. 3. Strabismus • • • • • • Squint Misalignment of extra ocular muscle Misalignment of eye position Misalignment of eye movement Disorder in fusion Disorder visual function  Binocular single vision (BSV)
  4. 4. Position of gaze • Primary position – Straight ahead • Secondary position – Straight up, straight down – Right gaze, left gaze • Tertiary position  Four oblique position – Up and right, up and left – Down and right, down and left • Cardinal position 4
  5. 5. Extra ocular muscle (EOM) • Agonist – Primary muscle moving the eye in a GIVEN direction • Synergist – – – – – Muscle in the same eye As the agonist That can act with agonist Produce a GIVEN movement E.g : Superior rectus with Inferior oblique  elevate the eye • Antagonist – Muscle in the same eye as the agonist – That can act with in the direction opposite – E.g : Medial rectus and lateral rectus 5
  6. 6. Cardinal position and Yoke muscles RSR LIO Right Gaze LSR RIO RLR LMR LLR RMR RIR LSO LIR RSO Left Gaze 6
  7. 7. Basic • Yoke muscle – Two muscle (one in each eye) – Are Prime mover of their respective eyes – In GIVEN position gaze – E.g : right gaze  RLR and LMR simultaneously innervated and contracted  to be “yoked” together 7
  8. 8. Basic • Sherrington’s law for reciprocal innervation – Increased innervation and contraction of GIVEN EOM  – Accompanied by reciprocal decrease of innervation and contraction of its antagonist EOM 8
  9. 9. Basic • Hering’s law of motor correspondence – The state  equal and simultaneous innervation flow to Yoke muscle – Concerned with the desired direction of the gaze 9
  10. 10. Monocular eye movements A- elevation D- adduction B- depression E–extortion C- abduction F- intortion
  11. 11. EOM : Functions Muscle Primary Secondary Lateral rectus Abduction None Medial rectus Adduction None Superior rectus Elevation Adduction Intorsion Inferior rectus Depression Adduction Extorsion Superior oblique Intorsion Depression Abduction Inferior oblique Extorsion Elevation Abduction 11
  12. 12. Eye movement • Versions – Eyes move in the same direction • Vergences  Disconjugate binocular eye movement – – – – – Convergence Divergence Incyclovergence Excyclovergence Vertical vergence 12
  13. 13. Classification of strabismus A. Pseudostrabismus (false or apparent squint). B. True strabismus: 1. Latent squint (heterophoria) 2. Manifest squint (heterotropia) - non-paralytic (concomitant) - paralytic (non-concomitant)
  14. 14. Variation of deviation With gaze position or fixating eye • Comitant (Concomitant) – Deviation doesn’t vary in size with direction of gaze or fixating eye • Incomitant (Noncomitant) – Deviation varies in size with direction of gaze or fixating eye – Most  paralytic or restrictive – In acquired condition  may indicate neurologic or orbital problems or diseases 14
  15. 15. Pseudo-strabismus • In young infants, strabismus must be differentiated from the more common pseudostrabismus • Pseudo-esotropia as a result of a broad bridge of the nose. This is not a real eye crossing
  16. 16. Pseudo-deviations Pseudo-esotropia Epicanthic folds • Short interpupillary distance • Negative angle kappa • Pseudo-exotropia Wide interpupillary distance • Positive angle kappa •
  17. 17. In high myopia the, the fovea lies nasal to the optical axis. So, the corneal reflex lies temporal to the center of the cornea  Negative angle kappa . Large negative angle kappa (myopia) leads to pseudo-esotropia. Large positive angle kappa (hypermetropia) leads to pseudoexotropia.
  18. 18. (Brief) Classification of squint • Latent (Heterophoria) – Esophoria – Exophoria – Vertical ‘phoria – Fully compensated – Poorly compensated
  19. 19. (Brief) Classification of squint • Manifest (Heterotropia) – Esotropia (convergent) – Exotropia (divergent) – Vertical – Unilateral or alternating – Constant or intermittent (in Primary position, or in certain positions of gaze) – Accommodative
  20. 20. Assessment of squint • • • • • • Visual Acuity Cover Test Ocular Movements Convergence Fusion/Stereopsis? Measurement of angle (prisms)
  21. 21. Visual aquity • Recognition acuity : Lea symbols, HOTV, Snellen Chart • Detection acuity : Stycar Ball test • Resolution acuity : Lea Paddles
  22. 22. Sensory evaluation • Simultaneous macular perception • Worth four dot test • Stereopsis
  23. 23. Tests for sensory anomalies Worth four-dot test a - Prior to use of glasses b - Normal c - Left suppression/amblyopia d - Right suppression/amblyopia e - Diplopia Bagolini striated glasses a - Normal or ARC b- Diplopia c - Suppression d - Small suppression scotoma
  24. 24. • Qualitative tests for Stereopsis: – Lang’s 2 pencil test – Synoptophore • Quantitative tests for Stereopsis: – Random dot test – TNO Test – Lang’s stereo test
  25. 25. Tests for stereopsis Titmus • • Polaroid spectacles Figures seen in 3-D TNO random dot test • • Lang Frisby • • No spectacles ‘Hidden’ circle seen Red-green spectacles ‘Hidden’ shapes seen • • No spectacles Shapes seen
  26. 26. Motor evaluation • Extra ocular muscles • Cover test • Corneal reflex test – Hirschberg Krimsky Bruckner • Dissimilar image test – Maddox rod
  27. 27. Evaluation of motility • Two principle methods of evaluating ocular motility are: 1. Observation of ocular ductions, which are the actual monocular movements of the eye. 2. Observation of binocular ocular alignment, using cover/uncover and alternate cover testing.
  28. 28. Cover test: Exotropia
  29. 29. Cover test: Esotropia
  30. 30. Cover uncover test: Exophoria
  31. 31. Cover uncover test: Esophoria
  32. 32. Cover test detects heterotropia Uncover test detects heterophoria Alternate cover test detects total deviation
  33. 33. Prism cover test measures total deviation
  34. 34. Motility tests Tests versions and ductions Grades under/overaction Left inferior oblique overaction Left lateral rectus underaction
  35. 35. Hirschberg test
  36. 36. Krimsky test
  37. 37. Modified Krimsky test • Asymmetric positions of the corneal reflex in the pupils of each eye are indicative of strabismus, which may be measured by placing a prism before the fixating eye until the reflection is similarly positioned in both eyes • Base out prism for esotropia • Base in prism for exotropia • This is the direct reading of the squint angle.
  38. 38. Bruckner test • Is performed by using direct ophthalmoscope to obtain a red reflex simultaneously in both eyes. • If there is strabismus , the deviated eye will have a lighter and brighter reflex than the fixing eye. • Media opacities, Refractive errors, Strabismus
  39. 39. Dissimilar image tests Maddox wing Dissociates eyes for near fixation (1/3 m) • Measures heterophoria • Maddox rod White spot converted into red streak • Cannot differentiate tropia from phoria •
  40. 40. Measurements of ocular misalignment • Synoptophore - picture test • Measure misalignments, sensory and motor fusion and stereopsis • Predict BV post-surgery • Measure misalignments 9 positions of gaze
  41. 41. Key notes • Early intermittent neonatal misalignment common between birth and 2-4 months • BSV well established from 6 months • Sensitive period for development of vision and binocular reflexes • Suspected squint after 4 months (corrected) age should be referred for orthoptic assessment
  42. 42. Aniseikonia • Translated from Greek aniseikonia means "unequal images". • It is a binocular condition, so the image in one eye is perceived as different in size compared to the image in the other eye. • Two different types of aniseikonia can be differentiated: static and dynamic aniseikonia 42
  43. 43. Aniseikonia • Static aniseikonia or aniseikonia in short means that in a static situation where the eyes are gazing in a certain direction • The perceived (peripheral) images are different in size 43
  44. 44. Aniseikonia : Static 44
  45. 45. Aniseikonia • Dynamic aniseikonia or (optically induced) anisophoria means that the eyes have to rotate a different amount to gaze (i.e. look with the sharpest vision) at the same point in space • This is especially difficult for eye rotations in the vertical direction 45
  46. 46. Aniseikonia : Dynamic 46
  47. 47. Prismatic effect of decentred lens • Convex lens  two prisms cemented together at their BASEs • Concave lens  two prisms cemented together at their APEXs • Decentred lens  Prism effect  Base in or Base out Decrease convergence Increase convergence
  48. 48. Anisophoria • Is a condition in which the balance of the vertical muscles of one eye differs from that of the other eye  the visual lines do not lie in the same horizontal plane • Eye muscle imbalance  the horizontal visual plane of one eye is different from that of the other 48
  49. 49. Amblyopia Type : • Strabismic amblyopia – Frequently  in esotropia patients • Anisometropic (Refractive) amblyopia – Difference in refraction greater than 2.50 D • Isoametropic amblyopia – Bilateral refractive error grater than + 5.00 or – 10.00 D • Deprivation amblyopia – Caused by such as media opacities Deborah Pavan-Langston, 2008 49
  50. 50. Management of squint • • • • • Orthoptic assessment Cycloplegic refraction & fundoscopy Correct significant refractive error Allow for refractive adaptation (up to 6/18) Occlusion treatment for amblyopia (patches, atropine) • Orthoptic exercises (intermittent deviations) • Surgery
  51. 51. Binocular Single Vision
  52. 52. Early history Leonardo Da Vinci had realized that two images would be needed for stereo viewing, but never created a 3D painting
  53. 53. • 1838 Wheatstone Stereoscopes – 1848 Brewseter – 1881 Popularized by Oliver Wendell Holmes • 1853 Earliest Anaglyph photographs Viewmaster 1939-Today Equivalent
  54. 54. 20 Century th • 1908 Lippmann, Integral Imaging, Lenticular Printing • 1934 Polarizing Glasses (two synchronized projectors) • 1950s Anaglyph and polarizing glasses popular to counter rise of television • Next 3D picture and 3D motion picture
  55. 55. Journal of Medical Science and Clinical Research Volume1||Issue3||Pages149-154||2013 New Approach In Binocular Single Vision Assessment For Candidate Of Phacoemulsification Micro Surgeons Gede Pardianto1, Diyah Purworini2 Department of Ophthalmology, Komang Makes Hospital Belawan, Medan, North Sumatra, Indonesia 2 Putri Hijau Hospital, Medan, North Sumatra, Indonesia 1
  56. 56. BSV • State of simultaneous vision • Coordinated use of both eyes • Blending of sight from the two eyes to form a single percept
  57. 57. BSV • Normal – it is bifoveal – there is no manifest deviation. • Anomalous – images of the fixated object are projected from the fovea of one eye and an extrafoveal area of the other eye
  58. 58. BSV: Requires • Clear Visual Axis in both eyes • The ability of the retino-cortical to promote the fusion of two slightly dissimilar images  Sensory fusion • The precise co-ordination of the two eyes for all direction of gazes to deal with two images  Motor fusion
  59. 59. BSV: Advantage • • • • Single vision. The most precise kind of depth perception Enlargement of the field of vision Compensation for blind spot and other differences
  60. 60. BSV 3 levels – Simultaneous perception ( 2 images seen) – Fusion (Interpreting 2 images as one) – Stereopsis (3-D appreciation)
  61. 61. Development of BSV Most neonates show coarse re-fixation 1.Conjugate fixation 1st to develop (eyes follow object together) 2.Disjugate fixation (follow approaching object – convergence) 3.Fusional reflex (correct for change in image position) 4.Kinetic reflex (controlled accommodation & convergence)
  62. 62. Stereo fusion • Objects are “fused” when brain interprets disparate images in the two eyes as being the same object and perceives the depth of the objects • When disparity gets too large – Double vision, – or brain ignores input from one eye
  63. 63. Corresponding points • Pairs of points on each retina share a common visual direction • A point on the nasal retina of one eye will have a corresponding point on the temporal retina of the other eye
  64. 64. Normal retinal correspondence • Retinal correspondence is called normal when both the fovea have a common visual direction • The retinal elements nasal to the fovea in one eye corresponds to the retinal elements temporal to the fovea in the other eye
  65. 65. Abnormal retinal correspondence • The fovea of one eye has a common visual direction with an extrafoveal area in the other eye • This results in the eyes seeing binocularly single inspite of a manifest squint • When the normal eye is closed the extrafoveal element loses any advantage over the fovea of that eye  central fixation is over handled by the fovea  the anomalous eye moving to primary position  this is the basis of the cover test
  66. 66. Retinal rivalry • When dissimilar contours are presented to corresponding retinal areas  fusion becomes impossible  retinal rivalry  leads to confusion. • In order to remove this confusion  image from one of the eyes is suppressed.
  67. 67. Horopter A horopter is an infinitely thin plane drawn through all object points that project onto corresponding retinal points.
  68. 68. Panum’s fusional area • Range of depth’s that can be “fused” Panum’s fusional area
  69. 69. Binocular Convergence θ θ
  70. 70. Monocular Cue • Non-stereo depth cue • One eye can judge its • Patients with binocular vision defect  still can feel the depth perception
  71. 71. Monocular Cue • Occlusion  near objects block the view of distant objects • Apparent size  if two objects are actually the same size, but one appears smaller, then the small one is farther away than the larger  relative size • Motion parallax and Relative velocity near objects appear move faster than distant objects • Light and Shading  distance and colour • Overlapping contour*
  72. 72. Relative size
  73. 73. Motion parallax
  74. 74. Motion parallax • Translocation of the head • Cause the images of near objects to move opposite the head • The images of far objects to move with the head • Assuming the fixation point is at an intermediate distance
  75. 75. Light and shade
  76. 76. Over-lapping contours
  77. 77. Monocular cue • Perspective  parallel lines converge in the distance • Aerial perspective • Geometric perspective • Texture  becomes finer with distance • Colour change  colour becomes more blue with distance  Atmospheric effect • Haze  objects become fuzzy in the distance • Accommodation  our brain knows how hard our eyes are working to focus
  78. 78. Aerial perspective
  79. 79. Geometric perspective
  80. 80. Refractive age
  81. 81. Depth perception  Monocular cues  Non stereoscopic binocular clues  Stereopsis
  82. 82. Why fovea/periphery differences • Range of disparities in natural scenes. • Fovea - high depth acuity. • Periphery - provides coarse information about where to make convergence eye movements.
  83. 83. Mistake in BSV • Motoric – Squint • Refractive – Aniseikonia • Eye Sensoric – Amblyopia • Optical problems – Visual illusion • Brain Perception – Experience – Monocular cues – Visual illusion
  84. 84. Visual illusion
  85. 85. Visual illusion
  86. 86. Visual illusion
  87. 87. Visual illusion
  88. 88. Visual illusion
  89. 89. Size illusion
  90. 90. Beuchet chair
  91. 91. Beuchet chair
  92. 92. Ames room
  93. 93. Ames room
  94. 94. Visual illusion: Shadow effect
  95. 95. Visual illusion: Shadow effect
  96. 96. Visual illusion: just 2D
  97. 97. Visual illusion: Moving texture
  98. 98. Visual illusion: Colour
  99. 99. Visual illusion: Grid illusion
  100. 100. Visual illusion: Bleeped-up
  101. 101. Visual illusion: The confuse
  102. 102. Visual illusion: Floor painting
  103. 103. Visual illusion: Single photo
  104. 104. Visual illusion: Single photo
  105. 105. Visual illusion: Bistable
  106. 106. Visual illusion: Bistable
  107. 107. Visual illusion: Bistable
  108. 108. Visual illusion: Mirage A inferior mirage occurs when the air below the line of sight is hotter and has lower index bias than the air above it. A superior mirage occurs when the air below the line of sight is colder than the air above it.
  109. 109. Mirage: hot haze Heat shimmer  refers to the inferior mirage experienced when viewing objects through a layer of heated air
  110. 110. Visual illusion: Moonbow
  111. 111. Visual illusion: Halo A sun dog (or sundog), mock sunor phantom sun, scientific name parhelion (plural parhelia), is an atmospheric phenomenon that creates bright spots of light in the sky, often on a luminous ring or halo on either side of the sun. Sundogs may appear as a colored patch of light to the left or right of the sun, 22° distant and at the same distance above the horizon as the sun, and in ice halos. They can be seen anywhere in the world during any season, but they are not always obvious or bright. Sundogs are best seen and are most conspicuous when the sun is low.
  112. 112. Sunset green flash The optical phenomenon known as the green flash can occur at sunrise or sunset, and it’s most often seen over low, unobstructed horizons such as the ocean.
  113. 113. Sun pillar A Sun pillar is an atmospheric phenomenon caused when high-altitude ice crystals reflect the rising or setting Sun’s reddened light.
  114. 114. Scintillation or Grid illusion
  115. 115. Visual illusion: Optic 1. Thermal Inversion The Titanic was sailing from Gulf Stream waters into the frigid Labrador Current, where the air column was cooling from the bottom up, creating a thermal inversion: layers of cold air below layers of warmer air. Extraordinarily high air pressure kept the air free of fog.
  116. 116. Visual illusion: Optic 2. Superior Mirage A thermal inversion refracts light abnormally and can create a superior mirage: Objects appear higher (and therefore nearer) than they actually are, before a false horizon. The area between the false horizon and the true one may appear as haze.
  117. 117. Visual illusion: Optic 3. Iceberg Camouflage The Californian’s radio operator warned the Titanic of ice. But the moonless night provided little contrast, and a calm sea masked the line between the true and false horizons, camouflaging the iceberg. A Titanic lookout sounded the alarm when the berg was about a mile away—too late.
  118. 118. Visual illusion: Optic 4. Mistaken Identity • Shortly before the collision, the Titanic sailed into the Californian’s view—but it appeared too near and small to be the great ocean liner. • Californian captain Stanley Lord knew the Titanic was the only other ship in the area with a radio, and so concluded this ship did not have one.
  119. 119. Visual illusion: Optic 5. Morse Lamp • Lord said he repeatedly had someone signal the ship by Morse lamp “and she did not take the slightest notice of it.” • The Titanic, now in trouble, signaled the Californian by Morse lamp, also to no avail. • The abnormally stratified air was distorting and disrupting the signals.
  120. 120. Visual illusion: Optic 6. Distress Rockets Ignored • The Titanic fired distress rockets some 600 feet into the air—but they appeared to be much lower relative to the ship. • Those aboard the Californian, unsure of what they saw, ignored the signals. • When the Titanic sank, at 2:20 a.m. April 15, they thought the ship might be simply sailing away.
  121. 121. Conflicting Cues: Only binocular • Random Dot Stereograms
  122. 122. Conflicting Cues: Only binocular • Random Dot Stereograms
  123. 123. 3D ability: 3D movie The archetypal 3D glasses, with modern red and cyan color filters, similar to the red/green and red/blue lenses used to view early anaglyph films.
  124. 124. 3D ability: 3D movie Resembling sunglasses, polarized glasses are now the standard for theatrical releases and theme park attractions.
  125. 125. 3D ability: 3D movie A pair of LCD shutter glasses used to view XpanD 3D films. The thick frames conceal the electronics and batteries
  126. 126. 3D vision ability
  127. 127. 3D vision ability
  128. 128. 3D vision ability
  129. 129. 3D vision ability
  130. 130. 3D vision ability
  131. 131. 3D vision ability
  132. 132. 3D vision ability
  133. 133. 3D vision ability
  134. 134. 3D vision ability
  135. 135. 3D vision ability
  136. 136. 3D vision ability
  137. 137. 3D vision ability
  138. 138. 3D vision ability
  139. 139. 3D vision ability
  140. 140. 3D Vision: Game
  141. 141. The hidden tiger
  142. 142. Shape of life: Pareidolia
  143. 143. Loch Ness Monster
  144. 144. Loch Ness Monster
  145. 145. Beyond the lecture • • • • • I have seen with my own eyes! So now… What do you think? Seeing doesn’t mean believing Think again!

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