A-V pattern strabismus

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The presentation I have made and uploaded provides you with an in-depth insight into the patterns the strabismus may take following anomalies of extraocular muscles, deformities of the orbital structures,innnervational disturbances.
The author does not assume responsibility or legal liability for any errors in the text or for the misuse or misapplication of material in this work.
No copyright infringement, or plagiarism intended.
Amrit Pokharel

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A-V pattern strabismus

  1. 1. Amrit Pokharel
  2. 2. Patterns of StrabismusA PatternV Pattern
  3. 3.  A Pattern  Relative convergence on up gaze and relative divergence on down gaze  Minimum of 10-pd dioptres difference b/w upgaze and down gaze
  4. 4.  V Pattern  Relative divergence on up gaze and relative convergence on down gaze  Minimum of 15-pd dioptres difference b/w upgaze and down gaze  Thisallows for a slight physiological V pattern
  5. 5. Variants of A and V patterns include:X pattern: There is relative divergence on bothup- and downgaze.Y pattern: There is relative divergence on upgazewith no significant differencebetween the primary position and downgaze.λ pattern: There is relative divergence ondowngaze with no significant differencebetween the primary position and upgaze.♦ pattern: There is relative convergence on bothup- and downgaze.
  6. 6. „A‟ pattern
  7. 7. „V‟ pattern.
  8. 8. why necessary??? Common entity Countless surgical overcorrections and undercorrections have been made due to failure to recognise patterns
  9. 9. History… The alteration in the degree of convergence and divergence on gaze change --- Duane(1897)
  10. 10. History… Lancaster(1944) recommended measuring deviation in upgaze and downgaze Scobee(1947) emphasized using versions to detect oblique muscle OA
  11. 11. History… Albert suggested A pattern and V pattern Costenbader(1958) fully described and designated A and V patterns Knapp recommended surgery on dysfunctional oblique muscles for A and V patterns
  12. 12. Must-know points… Anatomy of EOMs  Only when there is integrity of a sensorimotor apparatus is there a BSV  Any anomaly---no normal BSV  Origin of EOMs
  13. 13. Must-know points… Anatomical pecularities of IO  Only EOM that does not originate from the orbital apex  Short tendon of less than 2 mm  The tendon-insertion lies within 2 mm of macula  Run shortest course  Only muscle to come in contact with other two muscles:IR and LR
  14. 14. Rotational axes
  15. 15.  Muscle Actions???
  16. 16. AETIOLOGY: A great deal has been advanced as regards the role of  Horizontal, vertical and oblique muscle dysfunctions  Facial characteristics  Abnormal muscle insertions
  17. 17. AETIOLOGY: But no unanimity concerning pathophysiology has been gained Several schools of thought have evolved and some of them which are into acceptance are presented here
  18. 18. AETIOLOGY: Horizontal school V pattern esotropia: OA of MR on downgaze OA of LR on upgaze V pattern exotropia: OA of LR on upgaze OA of MR on downgaze A pattern exotropia: UA of MR on downgaze  A pattern esotropia: UA of LR on upgaze
  19. 19. AETIOLOGY: Horizontal school  Ifthis were the case then in case of bilateral abducens paralysis, there would be invariably a case of A pattern esotropia  The pattern is only occasionally observed and this contradicts the mechanism championed by Urist
  20. 20. AETIOLOGY: Horizontal school  Ithas been found that there occurs an elevation or depression upon adduction  And this is a common feature in A and V pattern  Villascea shared a view that although some vertical elements could be present, the pattern strabismus could be treated with the horizontal surgery only
  21. 21. AETIOLOGY: Horizontal school  Also in EMG studies in V exotropia it was found that there occurred a cocontraction of both horizontal muscles of the fixating eye and abnormal LR activity of the deviating eye.  Thiswould not suffice to be a real aetiological factor
  22. 22. AETIOLOGY: Vertical school  Brown championed opinion that A or V pattern may be caused by primary anomalies in vertical muscles which have adductive function in tertiary action
  23. 23. AETIOLOGY: Vertical school A syndrome: with eyes looking up and elevators contracting, the increased adduction of eyes could be caused by OA ing SR and by UA ing IOs and with eyes looking down and the depressors contracting the increased abduction could be due to OA ing SOs and UA ing IR
  24. 24. AETIOLOGY: Vertical school V syndrome: the increased abduction of eyes when looking up would be due to OA ing IOs and the UA ing SR and the increased adduction in downgaze would be due to OA of IR and UA of SOs.
  25. 25. AETIOLOGY: Oblique school A syndrome: OA of SOs V Syndrome: OA of IOs
  26. 26. AETIOLOGY: Oblique school A syndrome: OA of SOs  Overaction may be primary or secondary to UA(paresis) of IOs.  SO is abductor and its abducting factor will be most noticeable in depression  There occurs relative divergence of eyes producing A pattern
  27. 27. AETIOLOGY: Oblique school V syndrome: OA of IOs  Overaction may be primary or secondary to UA(paresis) of SOs.  IO is abductor and its abducting factor will be most noticeable in elevation  There occurs relative divergence of eyes producing V pattern
  28. 28. AETIOLOGY: Anatomical factors:  Urrets-Zavalia reported association of A esotropia (with UA ing IOs) and V exotropia (with OA ing IOs) in patients with mongoloid features  Mongoloid features:  Hyperplasia of malar bones  Upward slanting of palpebral fissures  Straight lower lid margin
  29. 29.  Mongoloid feature Eg A eSotropia
  30. 30. AETIOLOGY: Anatomical factors:  Urrets-Zavalia reported association of V esotropia (with OA ing IOs) and A exotropia (with UA ing IOs) in patients with antimongoloid features  Antimongoloid features:  Hypoplasia of malar bones  Downward slanting of palpebral fissures  S-shaped contour of lid margin
  31. 31.  Antimongoloid feature V eSotropia
  32. 32.  Projection of the positions of the extraocular muscles onto a horizontal plane. Dimensions, to scale, are from measurements in rectilinear three- dimensional coordinates (see Table 2, Ruetes figures). The oblique muscles have nearly the same plane of action. (Modified from Hering E: The Theory of Binocular Vision. New York, Plenum Press, 1977.)
  33. 33. AETIOLOGY: Anatomical factors:  Normally the direction of the IOs and the reflected portion of the tendon of SO are || to each other in relation to the Y axis.  Sagitallisation or desagittalisation of oblique muscles due to variations in origin and/or insertion of muscles can result in pattern strabismus
  34. 34. AETIOLOGY: Anatomical factors:  Forexample plagiocephaly increases the angle b/w the reflected part of the SO and the plane of the IO  Thus decreasing depressing action of the SO and resulting in OA of IO
  35. 35. AETIOLOGY: Anatomical factors:  Coats reported the association of V pattern strabismus in 10 out of 14 cases of craniofacial synostosis  Paysse observed strabismus in 59% of patients with Spina bifida and 47% of strabismic patients had A pattern strabismus
  36. 36. AETIOLOGY: Muscle Insertion:  Many have reported anomalies in the insertions of horizontal recti muscles; thus, if the muscles insertions are higher or lower than normal, adduction or abduction is subsequently increased in upgaze or downgaze
  37. 37. AETIOLOGY: Muscle Insertion:  Raised insertion of MR has been found in pxs with elevation on adduction  In V pattern, the MR insertions were higher than normal and the LR insertions were lower than normal  Resultingin increased abduction of LR on elevation and increased adduction of MR on depression
  38. 38. AETIOLOGY: Muscle Insertion:  In A pattern, the LR insertions were higher than normal and the MR insertions were lower than normal  Resultingin increased adduction of MR on elevation and increased abduction of LR on depression
  39. 39. AETIOLOGY: Sensory Deprivation:  Guyton and Weingarten hypothesized that poor binocular function may result in pattern strabismus.  Deficient fusion is a/w excyclotorsion of globe  Withexcyclotorsion, MR becomes a partial elevator whereas SR has a reduced elevating component
  40. 40. AETIOLOGY: Sensory Deprivation:  Kusheralso discussed the effect that torsion of globe has on horizontal function in upgaze and downgaze
  41. 41. Prevalence: Co-existence of A or V pattern with horizontal strabismus is seen in  12.5% to 50% of cases Urist MJ. The etiology of the so called A and V syndromes. Am J Ophthal 1951; 46:245-267
  42. 42. Prevalence:100 87.7 80 58.4 60 35 40 17.5 15 20 0
  43. 43. Prevalence: According to 1964 American Academy of Ophthalmology: V eSo> A eSo> V eXo> A eXo However, a somewhat different distribution was reported by von Noorden and Oslon: V eXo> A eXo> V eSo> A eSo
  44. 44. Clinical Features Symptoms:  Age at presentation  58% of patients had age of onset at 12 months or younger out of 421 patients, as reported by Costenbader  Ifthe pattern is small in magnitude it may not be recognised until the early school when head posture becomes apparent or reading difficulties are noted.
  45. 45. Clinical Features Symptoms:  Asthenopia and Diplopia  A eXotropia and V eSotropia
  46. 46. Clinical Features Signs:  Anomalous Head Posture  11% of patients with alphabet patterns Kushner BJ. Ocular causes of abnormal head posture. Ophthalmology 1979; 86:2115
  47. 47. Clinical Features Signs:  Anomalous Head Posture  A eSotropia and V exotropia have fusion in the downward gaze  So usually have chin elevation
  48. 48. Clinical Features Signs:  Anomalous Head Posture V eSotropia and A exotropia have fusion in the upward gaze  So usually have chin depression
  49. 49. Clinical Features Signs:  Amblyopia  Same as found in other forms of strabismus  However,a dissertation titled “CLINICAL EVALUATION AND MANAGEMENT OF A OR V PATTERN TROPIAS IN SQUINT” prepared at the Minto Ophthalmic Hospital, Bangalore Medical College & Research Institute, Bangalore maintained:
  50. 50. Clinical Features 27.7 Amblyopia No Amblyopia 72.22
  51. 51. Clinical Features Signs:  Amblyopia  Ciancia found abnormal retinal correspondence in 89% of cases of A or V pattern
  52. 52. NRC11 89 89 ARC
  53. 53. Patients at high risk Craniofacial anomalies like craniosynostosis, spina bifida Antimongoloid lid fissures (A eXotropia and V eSotropia) Mongoloid lid fissures (A eSotropia and V eXotropia) Infantile esotropia (V eSotropia)
  54. 54. Crouzon syndrome
  55. 55. PSEUDOPATTERNS… Patients with accommodative eSotropia may have  Pseudo- V pattern This is particularly apparent if the patient is examined without hypermetropic correction as with  Uncorrectedhyperopia there is a tendency to accommodate in the primary gaze and downgaze, thus simulating a V pattern
  56. 56. Diagnosis Measure patient‟s alignment in 25º upgaze and 25ºdowngaze with the patient fixating an accommodative target at distance, with fusion prevented Urist MJ. The etiology of the so called A and V syndromes. Am J Ophthal 1951; 46:245-267
  57. 57. Diagnosis Measure patient‟s alignment in 25º upgaze and 35ºdowngaze with the patient fixating an accommodative target at 33 cm. Noorden, G. K. von, and Oslon, C.L.: Diagnosis and surgical management of vertically incomitant horizontal strabismus , Am. J. Ophthalmol. 60:434, 1964
  58. 58. Diagnosis
  59. 59. Diagnosis Full refractive correction should be worn and accommodation should be well controlled to prevent the appearance of pseudo V pattern
  60. 60. Diagnosis The position of sursumversion and deosursumversion may be achieved  By moving the fusion target upwards or downwards, or  By moving the patient‟s head downwards or upwards Stella found no difference in the measurements under both conditions. This view is supported by
  61. 61. Diagnosis Grading of Inferior oblique muscle overaction  Inferior oblique overaction is graded by observing the angle the adducting eye makes with the horizontal line as it elevates and abducts on lateral version to the opposite side  Grade 1- upto 15º angle with the horizontal line  Grade 2- upto 30º angle with the horizontal line  Grade 3- upto 60º angle with the horizontal line  Grade 4- upto 90º angle with the horizontal line
  62. 62. Diagnosis Grading of Inferior oblique muscle overaction  For practical purposes, oblique overaction is graded as  Mild- if hyperdeviation is present in sursumduction  Moderate- if hyperdeviation is present adduction  Severe-if hyperdeviation is present in primary position
  63. 63. Investigation Aims  To detect and measure A/V patterns  To assess ocular movements a/w A/V patterns  Toassess significance of A/V patterns for prognosis and management
  64. 64. Investigation Criteria for diagnosis  V pattern: minimum difference of 15 pd from upgaze to downgaze  A pattern: minimum difference of 10 pd from upgaze to downgaze (Knapp 1959) There is a physiological tendency to relatively diverge in upgaze, and thus the minimum standards required for a V pattern is larger than that for an A pattern
  65. 65. Investigation
  66. 66. Investigation
  67. 67. Investigation
  68. 68. Investigation
  69. 69. MANAGEMENT Pre Treatment Evaluation  Detailed History  Assessment of BCVA  Cycloplegic Refraction and correction  Measurement of angle of deviation in all the 9 positions of gaze for near and far, with and without optical correction  Uniocular and binocular motility with particular attention to the oblique muscle dysfunction
  70. 70. MANAGEMENT Pre Treatment Evaluation  Bielschowsky head tilt test to r/o associated fourth nerve palsy  Tests like Bagolini glasses, Worth‟s 4 dot test  Anterior segment evaluation  Posterior segment evaluation
  71. 71. MANAGEMENT Treatment  Nonsurgical Treatment  Use of oblique prisms: Conjugate and oblique prisms may be tried in patients with:  Diplopia  Small deviations  Patients not fit for surgery
  72. 72. MANAGEMENT Treatment  Nonsurgical Treatment  Use of oblique prisms: Conjugate and oblique prisms may be tried in patients with: Diamond reported good results with bilateral conjugate and oblique prisms in V eSotropia and diplopia The use of prisms resulted in the reorientation of the motility field Diamond S. V-Esotropia aided by conjugate oblique prism
  73. 73. MANAGEMENT Treatment  Treatment of Amblyopia  Conventional occlusion therapy to improve fixation and VA in the amblyopic eye  Occlusion therapy is effective till 12 years of age but few authors have seen improvement till 19 years of age so a trial of occlusion therapy is given to all patients till 18-19 years of age.
  74. 74. MANAGEMENT Treatment  Treatment of Amblyopia  Inverse occlusion in patients with EF to supress the non- foveal primary directionalisation and to encourage central fixation  After the central fixation in the affected eye is restored the occlusion is changed over to the fixing eye and treatment is continued.
  75. 75. MANAGEMENT Treatment  Surgical Treatment  Goals of treatment  To correct the horizontal and vertical alignment in useful positions of gaze  To eliminate motor obstacles to maintain and regain binocular single vision
  76. 76. MANAGEMENT Treatment  Surgical Treatment  Goals of treatment  To eliminate abnormal head posture  To improve the cosmetic appearance of the patient
  77. 77. MANAGEMENT Treatment  Surgical Treatment  Indications and timing of surgery  Difference of angle of deviation in upgaze and in down gaze of > 15 pd  Squint interfering with the development of BSV  Patients with AHPs
  78. 78. MANAGEMENT Treatment  Surgical Treatment  Indications and timing of surgery  Refractive error and amblyopia treated  Surgery before 8 yr usually results in the attainment of good fusion  But after 8 yr there may be post operative vertical, horizontal, torsional diplopia
  79. 79. MANAGEMENT Treatment  Surgical Treatment  Surgical options…
  80. 80. MANAGEMENTTerminologies Recession: the tendon of the muscle is severed from the globe at its insertion and reattached to the sclera Marginal Tenotomy: the muscle is weakened by means of a series of marginal incisions at right angles to the plane of the muscle
  81. 81. MANAGEMENTTerminologies Simple Tenotomy: the tendon of the muscle is severed from the globe at its insertion and not reattached by sutures Resection: the severed tendon of the muscle is severd from the gobe and reattached further forward on to the sclera
  82. 82. MANAGEMENTTerminologies Tucking or tenoplication: the muscle and/or its tendon is folded upon itself and the folds firmly stitched together so as to produce a shortening effect Myectomy: the muscle is cut near its origin, or near its insertion
  83. 83. References: von Noorden GK, Chapter 3 „Summary of the Gross Anatomy of the Extraocular Muscles‟ in “Theory and Management of Strabismus” 5th ed, The C.V.Mosby Company, 1996:41-52 Fiona J. Rowe, Chapter 11 „A and V patterns‟ in “Clinical ORTHOPTICS” 3ed ed, WILEY- BLACKWELL, 2012
  84. 84. References: Urist MJ. The etiology of the so called A and V syndromes. Am J Ophthal 1951; 46:245-267 von Noorden GK, Chapter 17 „A and V patterns‟ in “Theory and Management of Strabismus” 5th ed, The C.V.Mosby Company, 1996:41-52
  85. 85. References: Pradeep Sharma. Chapter 6 „Examination Of A Case Of Squint‟ in “Strabismus Simplified”, 3rd reprint, 2004 von Noorden GK, Chapter 4 „Physiology of the Ocular Movements‟ in “Theory and Management of Strabismus” 5th ed, The C.V.Mosby Company, 1996:41-52
  86. 86. References:

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