Motor evaluation of strabismus


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  • Structures of eyes determine the position of eyes such that eye are able to lie in orbits and their visual axes are aligned correctly to one another at rest and during movement.
  • When the line is seen slanted toward the nose, an excyclodeviation is present.
    The line is always tilted in the direction in which the offending muscle would rotate the eye if it were acting alone.
  • Motor evaluation of strabismus

    1. 1. MOTOR EVALUATION OF STRABISMUS 07/24/14 Uri 1 Gauri Shankar shrestha, M.Optom, FIACLE Lecturer Sameer Bhaila, B.optom II year
    2. 2. Contents  Introduction  Detection of phoria and tropia Position of the globes Observation of head position  Determination of presence of deviation  Measurement of deviation Objective methods Subjective methods 07/24/14 2
    3. 3. BINOCULAR VISION  Vision achieved by co-ordinated use of both eyes.  The image which arise in each eye separately are appreciated as a single mental impression  Mainly three mechanisms a) Sensory b) Motor c) Central 3
    4. 4. Motor Mechanism  Concerned with maintenance of two eyes in correct positional relationship at rest and during movement.  Motor mechanism includes following factors Anatomical or static factor  Structure of orbits and their contents Physiological or dynamic factors 407/24/14
    5. 5. Physiological factor a) Postural reflex  Movement of eyes co-ordinate during the movement of head relative to body or body relative to space. Independent of visual stimuli. 507/24/14
    6. 6. b) Psycho-optical reflex Dependent on visual stimuli. Fixation reflex Re-fixation reflex Conjugate reflex Disjunctive or vergence fixation reflex Corrective fusional reflex 607/24/14
    7. 7. c) Kinetic reflex Maintenance of two eyes in their correct relative positions within orbits as a result of a controlled accommodation convergence relationship. Accommodative convergence Convergence induced accommodation 707/24/14
    8. 8. HETEROTROPIA: A manifest strabismus HORIZONTAL- esotropia or exotropia VERTICAL- hypertropia or hypotropia TORSIONAL- incyclo or excyclodeviation Combined horizontal, vertical and/or torsional 07/24/14 8
    9. 9. Concomitancy  Concomitant strabismus The deviation does not vary in size with direction of gaze or fixating eye  Noncomitant strabismus The deviation varies in size with direction of gaze or fixating eye 07/24/14 9
    10. 10. Observation of head posture  Patient with comitant horizontal heterotropias have normal head position.  Head position in nystagmus  Possibility of head to turn into null direction  Patient having high U/L amblyopia turn their head away from amblyopic eye 10
    11. 11.  Abnormal head positions common in connection with incomitant and paretic deviations  Purpose: relieve the paretic muscle sufficiently so that binocular single vision can be obtained.” -Bielschowsky  07/24/14 11 Observation of head posture
    12. 12. Abnormal head position take either the form of tipping the chin up or down, a face turn or a head tilt to one shoulder.  Patient with A and V pattern deviation tend to carry head with chin depressed or elevated. Patient with right lateral rectus paresis turn face to right. 1207/24/14
    13. 13. Subjective Tests Diplopia test  Red Glass test  Tangent screen  Maddox Rod  Maddox Wing  Maddox double rod test Haploscopic test  Lancaster R-G test Von Graefe method Measurement of Deviation Objective tests Prism and cover test Major Amblyoscope Corneal reflection tests  Hirschberg Method  Krimsky’s Method Ophthalmoscopy 07/24/14 13
    14. 14. OBJECTIVE TESTS 07/24/14 14
    15. 15. Determination of presence of deviation COVER TEST  Differentiates  The deviation is latent or manifest  The direction of deviation  The fixation behavior  Whether visual acuity is significantly decreased in one eye 07/24/14 15
    16. 16. Factors to be specified during a cover test Factor specified Choices Type of deviation Phoria or Tropia Frequency (if strabismic) Constant or Intermittent Laterality (if constant strabismic) Unilateral or Alternating Magnitude In prism diopters Direction Eso, Exo, Hypo, Encyclo, Excyclo or combination Comitancy Comitant or Incomitant Refractive correction In Diopters Test distance In meters 16
    17. 17. PRISM and COVER TEST  There will be no movement of the eyes when the selected prism causes the image to fall on the fovea. 07/24/14 17
    18. 18. Inaccuracy can be caused by 1. Inaccurate fixation due to blind eye 2. Presence of eccentric fixation 3. Inappropriate positioning of prism 4. Effect of refractive correction 07/24/14 18
    19. 19. MEASUREMENT with the MAJOR AMBLYOSCOPE Consists of 1. Chinrest 2. Forehead rest 3. Two tubes carrying targets seen through an angled eye-piece one for each eye 07/24/14 19
    20. 20. SYNAPTOPHORE 07/24/14 20
    21. 21. Use  Artificially performs cover tests  Measure subjective and objective angle of deviation  Measures horizontal, vertical, oblique deviation  Measures fusion ranges  Measures the grades of BSV  Measure ARC, Suppression, stereopsis, Horror Fusionis, measure foveal scotoma  Useful in visual training 21
    22. 22. CORNEAL REFLECTION TESTS (Hirschberg Method)  Estimation/ measurement of the deviation by observing the first purkinje image  Especially preferred when: In young children, unable to maintain fixation for a longer than a moment The amount of deviation cannot be determined by the prism and cover test or by any subjective tests. 07/24/14 22
    23. 23. 07/24/14 23
    24. 24.  1mm of decentration of the corneal reflection  =7° of deviation of the visual axis Hirschberg  1 mm displacement ~7 or 15 Brodie 1987  1mm displacement~20-22 Hasebe at al 1998 07/24/14 24
    25. 25. 07/24/14 25
    26. 26. Krimsky’s method  Prism is used to change the position of the corneal reflection in the deviating eye.  Amount of prism needed to reposition corneal reflection in the deviating eye to the normal position 07/24/14 26
    27. 27. 27
    28. 28. OPHTHALMOSCOPY  Fovea – 0.3 dd below a horizontal line extending through the geometric center of optic disc. 28 Excyclotortion Incyclotortion
    29. 29. SUBJECTIVE TESTS Based on Diploscopic principle Haploscopic principle 07/24/14 29
    30. 30. DIPLOSCOPIC TEST  Determination of the subjective localization of a single object point imaged on the fovea of the fixating eye and on extra-foveal retinal area in the other eye 30  Red glass test  Tangent screen  Maddox rod  Maddox wing  Double Maddox rod  Bagolini Striated lenses
    31. 31. Red glass test  A red glass is placed in front of one eye.  Pt fixates a small light source and states whether the red light is to the right or to the left and above or below the white light.  If the white fixation light is in the center of the maddox cross, pt must state the numbers near which the red light is seen. 07/24/14 31
    32. 32. 07/24/14 32
    33. 33. Tangent screen test  A green Maddox rod is held before the pt’s right eye while the left eye views a scale of red trans-illuminated number.  The white light at the center of the scale produces the streak, while the red numbers and green colored rod eliminate the additional streaks 33
    34. 34. Maddox rod  Consists of small glass rods (a series of plano-convex cylinders in red or white) causes an astigmatic elongation of the fixation light  Produce a vertical or horizontal streak to measure the horizontal and vertical deviation. 07/24/14 34
    35. 35. 35
    36. 36. Vertical rod to measure the vertical deviation  Maddox rod is oriented vertically in front of one eye and a measuring prism in other  Starting with 8 or 10 prism base up or base down prism the amount of prism power is gradually reduced until pt reports the horizontal streak goes through the spot 36
    37. 37. 37
    38. 38. Horizontal rod to measure lateral phoria  Uses horizontally oriented distance test chart having a spot light in center and numbers or letters extending on either side  Horizontally oriented Maddox rod is placed in front of one eye and the pt is asked to report the position of the vertical streak, the number letter or through the spot. 07/24/14 38 H G F E D C B A 0 1 2 3 4 5 6 7 8
    39. 39.  Maddox rod on RE If light streak pass through numbers Uncrossed diplopia- esophoria through letters Crossed diplopia- exophoria 07/24/14 39 H G F E D C B A 0 1 2 4 5 6 7 8 H G F E D C B A 0 1 2 4 5 6 7 8
    40. 40. 4007/24/14
    41. 41. Maddox wing  For amount of heterophoria in near fixation (1/3m)  A vertical arrow is presented to one eye and a horizontal tangent scale to the other to give the measurement of the horizontal phoria .  A horizontal arrow and vertical scale are used to measure the vertical imbalance. 07/24/14 41
    42. 42. MADDOX WING 07/24/14 42
    43. 43. 43 07/24/14
    44. 44. Maddox double rod test  Quantitative determination of cyclodeviation  Red and white maddox rods are placed in the trial frame in front of each eye.  Direction of glass rods is aligned with the 90° mark of trial frame
    45. 45.  A spot light is shown, for which the pt sees horizontal streaks.  If one line appears slanted toward the nose, excyclotropia is present. Maddox rod is turned until the red line is seen parallel with the white line. E.g. toward the 100° mark of the right trial frame, 10° right exotropia is present 07/24/14 45
    46. 46. 07/24/14 46
    47. 47. Bagolini striated glasses Produce an image of a streak of light, perpendicular to the axis of striations when viewing a spot light. Prism can be added to shift the streaks of light 07/24/14 47
    48. 48. HAPLOSCOPIC TESTS  Two test objects rather than one are presented to the patient  Visual field of two eyes are differentiated and dissociated by presenting different target with major amblyoscope Each eye with different color filter Polaroid projection
    49. 49. Lancaster test / R-G test  Uses a window shade type of screen (ruled into squares of 7cm) so that at distance of 2m each square subtends approx 2°  Pt wears red green reversible goggles  2 projectors are used  Red with examiner  Green patient  Image formed by projector are linear and measured
    50. 50.  In NRC,  Separation of the streaks on the screen = deviation of the visual axes  Titling of streak indicates presence of cyclotropia  Tilt of the retinal image is opposite to the tilt of the horizontal line as seen by the observer.
    51. 51. Von Graefe Method  The method of phoria measurement in which a dissociating prism is placed in front of one eye and a measuring prism in front of the other eye  The dissociating prism should be strong enough to cause diplopia 07/24/14 51
    52. 52.  A base down prism is placed in front of one eye causes the image on the retina to be displaced downward, below the macular area, so the object that formerly was seen straight ahead is then seen as being displaced upward 07/24/14 52
    53. 53. Measuring lateral phoria  Target: vertical line of 20/20 letters  A vertical prism of 7/8 pd is placed in front of one eye  A base in prism as the measuring prism in other eye  Pt is asked to report when the two columns of letters are on the same level.  Prism power is reduced until the patient reports alignment. 53
    54. 54. Measuring vertical phoria  When dissociating for the vertical phoria measurement, base in prism is used  Eyes are able to make much larger fusional convergence movements than fusional divergence movements.  15pd BI in one eye and a measuring prism BU or BD in other eye 07/24/14 54
    55. 55.  Target: a horizontal row of 20/20 letters on the chart at 6m or 40cm.  Pt is asked to report when the two rows of letters are on the same level.  Prism power is reduced until the patient reports alignment. 07/24/14 55
    56. 56. Hess Screen Test:
    57. 57. Hess chart of Left VI CN Palsy: Contraction of left chart and expansion of right Left chart - marked underaction of lateral rectus and mild overaction of medial rectus Right chart - marked overaction of medial rectus
    58. 58. Diplopia Charting:
    59. 59. Diplopia Charting:…
    60. 60. References 1. Binocular vision and ocular motility- Gunrter K Von Noorden 2. Primary care optometry- Theodore Grossvenor 3. Clinical orthoptics-Fiona J. Rowe 4. Clinical visual optics-Bennett & Rabbetts 5. Internet 07/24/14 60
    61. 61. Thank you...