Heterophoria n tropia

1. MEASUREMENT OF HETEROPHORIA AND HETEROTROPIA Presenter: Junu Shrestha 2 nd year B . Optom 12 th May 2013 Moderator: Gauri Sankar Shrestha 5/12/2013 1

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 5/12/2013 2

3. HETEROPHORIA Hetero- different Phoria – physiological position of rest Is the condition of eye in which the directions that the eyes are pointing are not consistent with each other Is a latent strabismus in which visual axes are normally directed to the point of fixation but deviate when the eyes are dissociated. Introduction 5/12/2013 3

4. The tendency of the lines of sight to deviate from the relative positions necessary to maintain single binocular vision for a given distance of fixation, this tendency being identified by the occurrence of an actual deviation in the absence of an adequate stimulus to fusion and o ccuring in variously designated forms according to the relative direction or orientation of the deviation. 5/12/2013 4

5. Compensating heterophoria Is the condition where heterophoria is asymptomatic. When fusional reserve is used to compensate for heterophoria . It is aka compensating vergence . 5/12/2013 5

6. Decompensating heterophoria When heterophoria is not overcome by fusional vergence , signs and symptoms appear It may lead to squint or stabismus 5/12/2013 6

7. B Angle of heterophoria Exophoria showing divergence or abduction behind the cover 5/12/2013 7

8. If the visual axes are found to be parallel when the patient views a distant object and all stimuli to fusion have been eliminated, the condition is called ORTHOPHORIA. if the visual axes converge toward one another – ESOPHORIA. If the visual axes diverge away from one another – EXOPHORIA. If one of the visual axis deviates above or below – HYPERPHORIA. 5/12/2013 8

9. HETEROTROPIA Is the manifest deviation in which fusional control is absent (motor fusion) Aka squint or strabismus 5/12/2013 9

10. Concomitant strabismus The deviation does not vary in size with direction of gaze or fixating eye Aka comitant strabismus 5/12/2013 10

11. Noncomitant strabismus The deviation varies in size with direction of gaze or fixating eye Most incomitant strabismus is paralytic or restrictive 5/12/2013 11

12. Heterotropia can be HORIZONTAL- esotropia or exotropia VERTICAL- hypertropia or hypotropia TORSIONAL- incyclo or excyclodeviation Combined horizontal, vertical and/or torsional 5/12/2013 12

13. Angle of Heterotropia B Left exotropia , showing adduction of the deviating left eye to take up fixation and corresponding abduction of the right eye behind cover LE RE 5/12/2013 13

14. DETECTION OF PHORIA & TROPIA POSITION OF THE GLOBES Estimating the relative position of the eye is to have the pt. fixate a penlight at near vision and then at distance If reflected images from the 2 corneas appear centered under both conditions – visual axes are aligned 5/12/2013 14

15. An angle kappa is formed by failure of the pupillary and visual axes of the eye to coincide. Pupillary axis- line passing through the centre of the apparent pupil perpendicular to the cornea. Visual axis – aka line of sight, connects the fovea with the fixation point. Angle kappa is formed at the intersection of these two axes at the center of the entrance pupil. 5/12/2013 15

16. The pupillary axis touches the posterior pole of the globe slightly nasal and inferior to the fovea The corneal reflection of a penlight is not centered but lies slightly nasal to the center positive angle kappa If the fovea’s position is nasal to the point at which the optical axis cuts the globe’s posterior pole, the corneal reflection of a light will appear to lie on the temporal side of the pupillary center negative angle kappa 5/12/2013 16

17. O F 5/12/2013 17

18. In high myopia, peudoesotropia is seen due to nasal displacement of the fovea. In Retinopathy of prematurity, the macula is pulled in the temporal direction, resulting in positive angle kappa aka pseudoexotropia . 5/12/2013 18

19. Size of angle Kappa Positive angle kappa ranges - 3.5° to 6.0° average 5.082° in emmetropic eyes In hypermetropic eyes - 6.0° to 9.0° average - 7.55° In myopic eyes – 2.0° may even be negative Donders FC; On the anomalie s of Accommodation and Refraction of the Eye 5/12/2013 19

20. Clinical significance Since angle may simulate , conceal or exaggerate a deviation, the angle kappa must be considered to obtain the best estimate of the actual deviation. 5/12/2013 20

21. Observation of head posture Pts with comitant horizontal heterotropias have normal head position. In nystagmus , the frequency and amplitude may reduce or dampens in certain direction where the visual acuity is optimal. Head is turned to that direction when looking straight ahead. Pt having high U/L amblyopia turn their head away from amblyopic eye 5/12/2013 21

22. Abnormal head positions in connection with incomitant and paretic deviations are usually assumed to obtain binocular co-operation or to avoid diplopia . “The pt chooses the least inconvenient position of the head by which the paretic muscle is sufficiently relieved so that binocular single vision can be obtained.” - Bielschowsky 5/12/2013 22

23. Determination of presence of deviation COVER TEST Differentiates orthotropia from an ocular deviation The deviation is latent or manifest The direction of deviation The fixation behaviour Whether visual acuity is significantly decreased in one eye 5/12/2013 23

24. A cover is placed briefly before the eye that appears to fixate while the pt looks a small object, or a 6/9 VA target Performed for distance and near. Covering one eye of a patient with normal binocular vision interrupts fusion Eg . If a pt has heterotropia and the fixating eye is covered, the opposite eye will move from heterotropic position to take up fixation and the covered eye will make a corresponding movement in accordance with Hering’s law. 5/12/2013 24

25. If there is no manifest deviation i.e. no movement of the fellow eye when either eye is covered, a cover-uncover test will determine the latent deviation. The covered eye is examined just after uncover. Eg . If a pt has heterophria , the covered eye will deviate in the direction of the heterophoric position. When the eye is uncovered , it will move in opposite direction to reestablish binocular fixation. 5/12/2013 25

26. The possible results of the cover and cover-uncover test are On covering the seemingly fixating eye: No movement of the other eye- there was binocular fixation before cover Movement of redress of the other eye: a manifest deviation was present before cover 5/12/2013 26

27. On uncovering the eye: Movement of redress of the uncovered eye ( fusional movement), no movement of the other eye: heterophoria is present No movement of either eye; uncovered eye deviated; opposite eye continues to fixate: alternating heterotropia is present Uncovered eye makes movement of redress and assumes fixation with one eye; preference of fixation with one eye: a U/L heterotropia is present. 5/12/2013 27

28. Modified Cover Test Introduced by Speilmann A translucent occluder is used. Covering both eyes with translucent occluders permits a quick preliminary determination of whether an esotropia is of refractive –accommodative or non-accommodative origin. 5/12/2013 28

29. 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 5/12/2013 29

30. 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 and fundus photorgaphy 5/12/2013 30

31. OBJECTIVE TESTS 5/12/2013 31

32. PRISM and COVER TEST Principle: there will be no movement of the eyes when the selected prism causes the image to fall on the fovea. A cover is placed alternating in front of each eye while the pt maintains fixation. The eye that is uncovered makes a movement of redress in the direction opposite that of the deviation. 5/12/2013 32

33. To measure esotropia , the prism must be placed base out, for an exotropia – base in, for aright hypertropia – base down in front of RE or base up in front of LE. Reduces the movement of redress and the prism strength is increased until the movement is offset. In pts with horizontal and vertical deviation, 1 st the horizontal deviation is neutralised with prism and then to vertical deviation. 5/12/2013 33

34. Physiologic basis Redress in the prism and cover test is a psycooptical reflex movement that occurs when the eye fixates. The sensory origin of this reflex movement is from the stimulation of a peripheral retinal area in the deviated eye by the fixation object. To place the fixated image on the fovea 5/12/2013 34

35. Movement is quantitative and is directly proportional to the distance of the fovea from the stimulated peripheral retina. Placing prisms of increasing power in front of the eyes brings the image of the fixated object closer to the fovea, causing a corresponding decrease in movement of redress. 5/12/2013 35

36. Adequate fixation target and a technique that ensures relaxed accommodation and maximum dissociation is used. For distance fixation 6/9 VA symbol and a picture target for near. At 6m the stimuli to accommodation and convergence are assumed to be zero (although the actual stimulus to accommodation is 0.17D and for convergence is 1p.d.)at 40cm the stimulus to accommodation is 2.50D to convergence is 15p.d.(for IPD 64mm) 5/12/2013 36

37. Limitations of prism cover test Presupposes accurate fixation and cannot be performed if the deviating eye is blind or has grossly eccentric fixation. In EF, the test provides wrong measurements as the movement of redress stops when the stimulus falls on the eccentric retinal area not the fovea. With loose prisms, when a low prism is added to a high power prism, the arithmetic addition doesnot give the resultant power 5/12/2013 37

38. 3.The amount of deviation measured by an ophthalmic lenses is variable depending on position(how the prism is held). Eg a 40 glass prism with a posterior face held in frontal position gives only 32 of effect. Glass prisms are calibrated for use in the prentice position, i.e. the posterior face of the prism is perpendicular to the line of sight of the deviating eye. Plastic prisms are calibrated for use in the frontal plane position i.e. parallel to the infraorbital rim. 5/12/2013 38

39. 4.When measuring large angle horizontal deviation with a prism bar, even slight oblique shifts of the bar can include a vertical displacement of the image, mimic a vertical deviation and cause vertical diplopia 5.Spectacle lenses affects the measurement of strabismic deviation. Plus lenses decrease and minus lenses increase the measured deviation. Becomes clinically significant with powers of more than 5D 5/12/2013 39

40. MEASUREMENT with the MAJOR AMBLYOSCOPE Consists of Chinrest Forehead rest Two tubes carrying targets seen through an angled eye-piece one for each eye 5/12/2013 40

41. SYNAPTOPHORE 5/12/2013 41

42. Tubes are placed horizontally and supported by a column Distance between the tubes can be adjusted -correspond accurately to the pt’s IPD. The axis of tube is in line with the center of rotation of the eyes. Adjustments for vertical separation of targets and cyclorotational adjustments Illumination system Increase or decrease stimulus luminance 5/12/2013 42

43. Position of targets is fixed in focal plane of a +6.0D or +6.5D lens so that they are at optical infinity To induce accommodation, auxilliary minus lenses are placed in front of the eye pieces Deviation is measured by moving the arms of the major amblyoscope into the position that images of the target fall on the respective foveal areas. 5/12/2013 43

44. The arms are moved until there is no further fixation movement of the eyes in an alternate cover test.(either by actual covering or by alternately extinguishing the light on one side of the instrument) Horizontal deviations are compensated for by moving the synaptophore arms, vertical deviations by elevating or depressing the synaptophore pictures. 5/12/2013 44

45. When one eye is deeply amblyopic without the capacity for fixation the angle can be determined by shifting the synaptophore arm in front of the amblyopic eye until the corneal reflex is centered in the pupil 1.If corneal fixation is present, place one arm at zero and the other at presumed angle of deviation. Both pictures are illuminated. Pt fixates on center of one picture. 5/12/2013 45

46. This picture is shut off and the examiner observes whether the other eye makes a fixation movement. The arms are shifted until no fixation movement is visible. Between each phase, both pictures are illuminated so that binocular vision is possible. Aka monocular cover test or the simultaneous prism cover test. 5/12/2013 46

47. 2.Both pictures are shown alternately and the synaptophore arms are adjusted until no refixation movement develops. Aka Alternate cover test and alternate prism cover test since no binocular vision is possible. 5/12/2013 47

48. CORNEAL REFLECTION TESTS Estimation/ measurement of the deviation by observing the first purkinje image Especially preferred when: The deviated eye is blind or has low VA 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. 5/12/2013 48

49. Pt is instructed to watch a penlight held at 40cm by the examiner Observes the corneal reflexes in the pts eye If no tropia exists, each corneal reflex will be located approx 0.5mm nasal to the center of the pupil. 5/12/2013 49

50. The corneal reflection is on the nasal side of the deviated eye in exotropia , on the temporal side in the esotropia , below the corneal center in hypertropia and above it in hypotropia . 5/12/2013 50

51. Hirschberg Method When both eyes unoccluded and the pt still fixates the penlight, the position of the corneal reflexes in both eyes under binocular condition is noted and is compared with the corresponding positions and with the corresponding position under monocular condition. 5/12/2013 51

52. “ Each 1mm of decentration of the corneal reflection correspond to 7° of deviation of the visual axis.” Hirschberg 1mm displacement ~7 or 15 Brodie 1987 1mm displacement~20-22 Hasebe at al 1998 5/12/2013 52

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54. 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 angle lambda 5/12/2013 54

55. A penlight is held 50cm in the midplane Prism bar is placed in front of the fixating eye and is increased until the corneal reflection in the deviating eye moves to angle lambda position. 5/12/2013 55

56. OPHTHALMOSCOPY and FUNDUS PHOTOGRAPHY Fovea – 0.3 dd below a horizontal line extending through the geometric center of optic disc. Excyclotropia Incyclotropia 5/12/2013 56

57. SUBJECTIVE TESTS Based on Diploscopic principle Haploscopic principle 5/12/2013 57

58. DIPLOPIA TEST Determination of the subjective localization of a single object point imaged on the fovea of the fixating eye and on extrafoveal retinal area in the other eye In esotropia , where the image of the fixation point in the deviated eye falls on a nasal area nasal to the fovea, there should be uncrossed diplopia . 5/12/2013 58

59. In exotropia , where the image of the fixation point in the deviated eye falls on a retinal area temporal to the fovea, there should be crossed diplopia . If retinal correspondence is normal, double images not only should be properly oriented but also should have a distance equal to the angle of squint. 5/12/2013 59

60. The distance of the double images is then a measure of the deviation; but with spontaneous diplopia , it is difficult for the patient to state whether the images are crossed or uncrossed. The two visual fields must be separated. 5/12/2013 60

61. 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. 5/12/2013 61

62. Red glass dissociate the light in addition to differentiate the two fields. Dissociation is important in Hetrophoria Intermittent heterotropia 5/12/2013 62

63. The red glass must be dark enough to make it impossible for the pt to see anything but the red fixation light to prevent fusional impulses from the surrounding of the fixation light. Generally the filter is placed before the fixating eye, which is less likely to suppress the darkened image of fixation light. 5/12/2013 63

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65. Tangent screen test Introduced by Freeman A green maddox rod is held before the pt’s right eye while the left eye views a scale of red transilluminated number. The white light at the center of the scale produces the streak, while the red numbers and green coloured rod eliminate the additional streaks thet would otherwise have been caused if white number had been used. 5/12/2013 65

66. The scale calibrated in prism dioptres for the assumed testing distance, is placed obliquely, and hence may be used to measure both horizontal and vertical deviations. Odd numbers are used on one side of the spot and even numbers on the other. 5/12/2013 66

67. Maddox rod Consists of small glass rods(a series of planoconvex cylinders in red or white) causes an astigmatic elongation of the fixation light and may be placed to produce a vertical or horizontal streak to measure the horizontal and vertical deviation. 5/12/2013 67

68. A streak image- oriented 90 from the axis of the cylinders Performed with refractive correction . 5/12/2013 68

69. Vertical rod to measure the vertical deviation Maddox rod is oriented vertically infront 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 5/12/2013 69

70. The magnitude, hyper eye ,test distance, refractive correction and technique should be recorded for the vertical deviation 5/12/2013 70

71. Horizontal rod to measure lateral phoria Both methods for near and distance Stabilization of accommodation is not significant for vertical deviations because fluctuation of deviations affect only the horizontal angle Can be assessed by Thorington method 5/12/2013 71

72. 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. H G F E D C B A 1 2 3 4 5 6 7 8 5/12/2013 72

73. Because each prism diopter of deviation at 6m results in a tangent distance of 6cm, to have 1 steps, the no. or letters must be placed 6cm apart 5/12/2013 73

74. Maddox rod on RE Numbers on right side If light streak pass through no. Uncrossed diplopia - esophoria through letters Crossed diplopia - exophoria 5/12/2013 74 H G F E D C B A 1 2 4 5 6 7 8 H G F E D C B A 1 2 4 5 6 7 8

75. Can also be used at 40cm At 40cm, each prism diopter of power is represented by a deviation of 0.4cm. Can also be designed to measure the vertical phoria by aligning the numbers and letters vertically above and below the light source. 5/12/2013 75

76. Since this method uses no. and letters, which exerts some control over accommodation this test doesnot present the problem of lack of control of accommodation 5/12/2013 76

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78. Maddox wing For amount of heterophoria in near fixation 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. Scales are mounted at the fixed viewing distance of 1/3m. 5/12/2013 78

79. MADDOX WING 5/12/2013 79

80. Maddox double rod test Quantitative determination of cyclodeviation Red and white maddox rods are placed in the trial frame. Red before RE and white before LE. Direction of glass rods is aligned with the 90° mark of trial frame 5/12/2013 80

81. A spot light is shown, for which the pt sees horizontal streaks. A vertical prism may be added to separate the images for easier identification. If one line appears slanted toward the nose, excyclotropia of RE 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 5/12/2013 81

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83. Bagolini striated glasses Produce an image of a streak of light, perpendicular to the axis of striations when viewing a spot light. Axes of striation at 90° If two lines fuse- no cyclotropia If not the amount by which the glasses are turned gives the direction and amount of cyclotropia 5/12/2013 83

84. HAPLOSCOPIC TESTS Two test objects rather than one are presented to the patient assumption: NRC Visual field of two eyes are differentiated and dissociated by presenting different target with major abmlyoscope Each eye with different colour filter Polaroid projection 5/12/2013 84

85. 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 red green reversible googles 2 projectors are used Red with examiner Green patient Image formed by projector are linear 5/12/2013 85

86. In NRC the streaks will be separated objectively on the screen by an amount corresponding to the deviation of the visual axes. Since the projected image is a line, the pts response may indicate the presence of cyclotropia when the streak is tilted. Tilt of the retinal image is opposite to the tilt of the horizontal line as seen by the observer. 5/12/2013 86

87. 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. 5/12/2013 87

88. 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 5/12/2013 88

89. 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 5/12/2013 89

90. Measuring lateral phoria Target: vertical line of 20/20 letters A vertical prism of 7 or 8 is placed in front of one eye A base in prism as the measuring prism in other eye 5/12/2013 90

91. If BU in LE and BI in RE, lower image towards left is seen by left eye and upper image towards right is seen by right eye. At this point, two procedures can be used Alignment method Flash method 5/12/2013 91

92. Alignment method The strength of the BI prism is decreased until both images are on same line. 0 - orthophoric But if the measuring prism indicates BI prism at alignment the pt is exophoric and if it indicates BO the pt is esophoric 5/12/2013 92

93. Flash method The prism strength is decreased but the eye is occluded in doing so. It prevents the continuous viewing of the charts preventing the chance of fusion. 5/12/2013 93

94. 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. 15 BI in one eye and a measuring prism BU or BD in other eye. 5/12/2013 94

95. 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. 5/12/2013 95

96. If the measuring prism is BD in LE, and if alignment obtained at 0 - orthophoria BD - left hyperphoria BU - Rt hyperphoria 5/12/2013 96

97. References Binocular vision and ocular motility- Gunrter K Von Noorden Primary care optometry- Theodore Grossvenor Clinical orthoptics -Fiona J. Rowe Clinical visual optics-Bennett & Rabbetts Internet 5/12/2013 97

98. Thank you ... 5/12/2013 98