Squint

strabismus test

1. Test for STRABISMUS Anuraag Singh

2. Strabismus- misalignment of the visual axis. Visual axis - line of vision extending from the point of fixation to the fovea Anatomical axis - is a line passing from the posterior pole through the centre of the cornea . Orthophoria -perfect alignment of the visual axes

3. It is the angle formed between visual axis and the anatomical axis As the fovea lies just temporal to the anatomical axis, a light shown into the cornea will cause reflex (on the visual axis) just nasal to the center of the cornea in both eyes (+ ve angle kappa = 5°). Angle of kappa

4. In high myopia the, the fovea lies nasal to the optical axis. So, the corneal reflex lies temporal to the center of the cornea simulating esotropia . Negative angle kappa (myopia) leads to pseudo- esotropia . Large positive angle kappa ( hypermetropia ) leads to pseudo- exotropia .

5. Heterophoria - (latent squint) tendency of the eyes to deviate. Ocular alignment maintained with effort. Heterotropia - (manifest squint) which is present at all times Esophoria - latent squint inwards turning of the eyes Esotropia - manifest squint inwards turning of the eyes Exophoria - latent squint outwards turning of the eyes Exotropia - manifest squint outwards turning of the eyes Hyperphoria / hypertropia - latent/manifest squint upwards turning of eyes Hypophoria / hypertropia - latent/manifest squint downwards turning of eyes

6. Horizontal muscles :- Medial rectus- Its sole action in the primary position is adduction. - occulomotor nerve supply Lateral rectus- Its sole action in the primary position is abduction - abducens nerve supply EOM

7. Vertical muscles Superior rectus- Primary action elevation (secondary actions are adduction and intorsion . - Oculomotor nerve supply Inferior rectus - The primary action is depression ; secondary actions are adduction and extortion. - O culomotor nerve supply

8. Superior oblique - The primary action is intorsion - secondary actions are depression and abduction . - oculomotor nerve supply Inferior oblique - The primary action is extorsion - secondary action are elevation and abduction . - oculomotor nerve supply Oblique Muscles

9. Listing plane is an imaginary coronal plane passing through the centre of rotation of the globe. The globe rotates on the X,Y and Z axes of Fick which intersect in Listing plane . The globe rotates left and right on the vertical Z axis. The globe moves up and down on the horizontal X axis. Torsional movements (wheel rotations) occur on the Y (sagittal ) axis which traverses the globe form front to back (similar to the anatomical axis of the eye ) Intorsion occurs when the superior limbus rotates nasally and extorsion on temporal rotation . Listing’s Plane

10. Ocular Movements Ductions Monocular movements around the axes of Fick. They consist of adduction , abduction elevation, depression, intorsion and extorsion . They are tested by occluding the fellow eye and asking the patient to follow a target in each direction of gaze.

11. Versions B inocular , simultaneous, conjugate movements ( in the same directon ) .

12. VERGENCES Vergences are binocular, simultaneous disconjugate or disjunctive movements. Convergence is simultaneous adduction. Divergence is outwards movement from a convergent position.

13. Positions of gaze:- Six Cardinal positions of gaze are those in which one muscle in each eye has to move the eye into that position as follows: Dextroversion Levoversion Dextroelevation Levoelevation Dextrodepression Levodepression Nine Diagnostic position of gaze are those in which deviations are measured. They consists of the six cardinal postions ,the primary position, elevation and depression .

14. A ntagonist - muscles of the same eye moving the eye in opposite direction (medial and lateral rectus) Synergists- muscles of the same eye moving it in the same direction (superior rectus and inferior oblique causing elevation) Yoke muscles- muscles of both eyes moving the eyes in same direction; medial rectus of both eyes Sherrington’s law- increase in innervation to one muscle causes decreased innervation to its antagonist (medial and lateral rectus) Hering’s law- equal innervation flows to yoke muscles in eye movement ( medial rectus of both eyes) Laws of ocular motility

15. Examination of Strabismus

16. Age of onset of deviation Is the deviation constant or intermittent? Is the deviation present for distance, near or both? Is it unilateral or alternating? Is it present only when the patient is inattentive or fatigued? Is it associated with trauma or physical stress? Old photographs Birth history Is there a family history of strabismus?. Are there any other medical problems? Is there a history of toxin or medication exposure? History

17. 1.Objective methods 2.Subjective methods 1.Objective methods:- Hirschberg corneal reflex test Krimsky’s test Bruckner test Cover uncover test Alternate cover test Prism bar cover test Synoptophore Measurement of Deviation

18. 2.Subjective methods:- Maddox rod test Maddox wing test Maddox tangent Double maddox rod Maddox double prism Hess screen Red green glass test Diplopia field

19. Hirschberg corneal reflex test Used as initial screening test for strabismus. Amount of deviation: note location of corneal light reflex 1 mm = 7° or 15Δ Corneal reflex at border Corneal reflex at limbus of pupil = 15° = 45°

20. Krimsky Test This test is used to centralize the corneal reflection in squinting eye as compared to the reflex in fixing eye. Results are expressed in prism diopter (PD). Convenient test for quick evaluation of the angle of strabismus, especially in the abnormal fixation of the squint eye.

21. Performed by using direct ophthalmoscope to obtain a red reflex simultaneously in both eyes. Deviated eye will have a lighter and brighter reflex than the fixing eye . Bruckner test positive for left eye esotropia Bruckner Test

22. 1.Cover test:- To detect a heterotropia Procedure:- 1.The patient fixates a straight ahead target 2.If a right deviation is suspected , the examiner covers the fixing left eye Note any movement of the right eye to take up fixation Cover uncover Test

23. No movement indicates orthotropia Adduction of right eye indicates right exotropria Abduction of right eye indicates right esotropia Down movement indicate right hypertropia Upward movement indicate right hypotropia Test is repeated on opposite eye

24. Cover test

25. Detects heterophoria Procedure:- Patient fixates a straight ahead distant target Examiner covers the right eye and after 2-3 seconds removes the cover No movement indicates orthophoria If the right eye had deviated while under cover ,a re-fixation movement is observed on being unconvered . Uncover test

26. Aduction ( nasal recovery) of right eye indicates exophoria and abduction ( temporal recovery ) indicates esophoria . Upward or downward movement indicates a vertical phoria . The test is repeated for the opposite eye

27. Dissociation test Reveals total deviation when fusion is suspended Procedure:- Right eye is covered for several seconds Occluder is quickly shifted to opposite eye for 2 seconds ,then back and forth several times Note the recovery as the eyes return to their pre-dissociated state Alternate cover test

28. A patient with well compensated heterophoria will have straight eyes before and after the test. A patient with poor control may decompensate to a manifest deviation

29. The prism cover test measures the angle of deviation It combines alternate cover test with prisms Procedure:- The alternate cover test is performed first Prism of increasing strength placed in front of one eye with base opposite the direction of deviation Alternate cover test is performed continously as stronger prisms are used Prism cover test

30. Amplitude of refixation gradually decreases End point reached when no movement is seen To ensure maximum angle is found , prism strength is increased until movement is observed in opposite direction Then reduced again to find neutral value Angle of deviation equals the strength of the prism

31. 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. Modified Cover Test

32. Consists of Chinrest Forehead rest Two cylindrical tubes with mirrored right angled bend and +6.50 D lens in each eyepiece. This optically sets the testing distance as equivalent to 6 m. Synoptophore

33. 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

34. Deviation is measured by moving the arms of the synaptophore into the position that images of the target fall on the respective foveal areas . Horizontal deviations are compensated for by moving the synaptophore arms, vertical deviations by elevating or depressing the synaptophore pictures . It can measure horizontal,vertical and torsional misalignments simultaneously. It can be used for grading the binocular vision

35. 1.First grade ( Simultaneous perception ) Tested by introducing two dissimilar but not mutually anatagonistic pictures , such as lion and a cage.

36. 2.Second grade ( fusion ) Ability of two eyes to produce a composite picture from two similar images, each of which is incomplete in one small different detail

37. 3.Third Grade ( stereopsis ) Ability to obtain an impression of depth Superimposition of two pictures of same object taken from slightly different angles

38. It is based on the principle of dissociation Maddox Rod consists of a series of plano cylinder lenses about 3 mm in diameter, mounted in a trial frame lens. A spot of light viewed through the Maddox Rod appears as an elongated streak. The Maddox Rod is often colored usually red. Maddox rod test

39. Used to find out presence of heterophoria or heterotropia Easy for patient to understand Easy to administer Very useful for vertical deviations. uses

40. Reduce room illumination. Maddox Rod is placed in front of one eye Measuring horizontal deviations maddox Rod axes are placed horizontal which produces vertical streak Measuring vertical deviations maddox Rod axes are placed vertical which produces horizontal streak Patient initially views with both eyes open procedure

41. Maddox Rod is placed horizontally (vertical streak) in front of right eye With strabismics , the Maddox Rod is best placed over the fixating eye Ensure that patient can see white light and streak simultaneously Ask if the streak is to the right or to the left of the light For horizontal deviation

42. Same procedure is followed except maddox rod is placed with its axes vertically producing horizontal streak of light If the horizontal streak of light is above the fixation light it indicates presence of hypo deviation If the horizontal streak of light is below the fixation light it indicates presence of hyper deviation Vertical deviation

43. It is based on the principle of dissociation Instead of maddox rod a red glass is used Tangent scale is used Maddox tangent

44. Procedue 1.Patient is asked to fix the white light 2.Through the red glass light looks like a red spot 3.In orthophorics red spot overlaps white light 4.In deviation red spot can be either on left or right of white light.

45. 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. Maddox wing

46. MADDOX WING

47. 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 Maddox double rod test

48. Screen contains a tangent pattern ( 2D projection of a spherical surface ) printed on dark grey background. Red lights ( can be individually illuminated ) indicate the cardinal positions of gaze Each square represents 5 of ocular rotation. Procedure :- 1.Patient seated 50cm from screen wearing red-green goggles ( red in front of right ) and holds a green pointer. 2.Examiner illuminates each point in turn which is used as point of fixation.seen only with right eye ( becomes fixating eye ) Hess test

49. 3.Patient asked to superimpose their green light on red light , so plotting the relative position of left eye.all points are plotted. 4.The goggles are then reversed and procedure repeated. 5.The relative positions are marked by the examiner on a Hess chart and connected with straight lines. In orthophoria two lights more or less superimpose in all nine positions of gaze.

50. Hess charting in RLR palsy

51. Suppression is an acquired cerebral function used by the patient to avoid confusion and diplopia. Patient may not be aware of suppression Suppression scotoma is present in tropias . It prevents diplopia. Tests for suppression :- 1.Worth four dot test 2.Prism 4 PD base out test 3.Red glass test 4.Synoptophore Suppression and eccentric fixation

52. It consists:- Self illuminating panel of 1.Two green 2.One red 3.One white Generally done at 6m Patient wears a red green glass :; red in front of right eye. When the patient looks through green glass the patient can see only green spots and white spot looks light green. While looking through red glass he can only see the red spot and white spot looks pink. Worth four dot test

53. When a normal patient looks with both eyes open, he sees two green, one red and one mixture of red and green. In case of left supression ,the patient will see two red lights. In case of right supression ;sees three green lights. If the patient sees five lights in presence of ocular deviation, patient has diplopia and normal retinal correspondence.

54. A patient with deviation and normal vision should experience diplopia unless he is ignorig or suppressing it. Procedure:- P atient fixes a white light A red glass put in front of deviated eye Patient become aware of second image as a red light If there is deep suppression only white light will be visible Red glass test

55. Special slides used to detect suppression Depth of suppression can be measured by altering the illumination of the slides. S ynoptophore

56. Normal retinal correspondence :- when anatomically corresponding areas of two eyes correspond to each other. Abnormal retinal correspondence

57. In abnormal retinal correspondence :- an extra foveal area of squinting eye and fovea of fixing eye have a common visual direction. It’s a crude method of retaining binocular vision in squint. More developed in microtropia

58. 1.Bagolini striated glasses 2.Worth four dot test 3.After image test 4.Synoptophore Bagolini striated glasses:- Bagolini glasses – plane - on one surface multiple parallel lines etched Procedure:- Glasses mounted o trialframe Done at 33cm or 6m Test for ARC

59. Spot of white light seen Both eyes are kept open Lens in right eye set at 45 o axis Lens in left eye set at 135 o axis

60. Patient sees only one slanting line – other is suppressed Lines cross each other (perfect cross), eyes are straight and have central fixation - NRC Deviation + perfect X - ARC

61. Shining vertical light thrown on fovea of right eye Similar (intensity and size ) horizontal light thrown on fovea of left eye Light thrown for 20 seconds Patient looks at fixation point Interpretation:- 1.Perfect cross with central gap – central fixation with NRC After image test

62. 2.Vertical after image shifted to right – ARC with right exotropia with central fixation 3.Vertical after image shifted to left – ARC with right esotropia with central fixation

63. 1.Uniocular or binocular Uniocular diplopia disappear on closing affected eye Binocular diplopia disappear on closing either eye 2.False and true images False image – formed in deviated eye at a point other than the macula. - blurred as compared to true image - may be separated from true image - distance may vary at different positions of gaze and head - may be tilted - Evaluation of Diplopia

64. Crossed diplopia – false image projected across the midline False image formed in direction opposite to displacement. Seen in Paralysis of adductors- MR,SR,IR Uncrossed diplopia – false image do not cross midline Seen in paralysis of abductors- LR,SO,IO Crossed and uncrossed diplopia

65. Qualitative tests for Stereopsis: Lang’s 2 pencil test Synoptophore Quantitative tests for Stereopsis: Random Dot test Titmus Fly Test TNO Test Lang’s Stereo Test Test for stereopsis

66. TNO TNO random dot test consist of seven plates of randomly paired red and green dots which are viewed with red-green spectacles. Within each plate the dots of one colour forming the target shape are displaced horizontally in relation to their paired dots of other colour.

67. Frisby Frisby stereotest consist of three transparent plastic plates of varying thickness. On the surface of ach plate are printed four squares of small randomly distributed shapes One of the squares contains a hidden circle,in which the shapes are printed on the reverse of the plate.

68. Lang Lang stereo test doesn’t require special spectacles Targets are seen alternately by each eye through the built in cylindrical lens Displacement of the dots creates disparity Can often be used in very young children who may reach out to touch the pictures.

69. Titmus Titmus test consist of 3D polaroid vectograph Two plates in form of booklet viewed through Polaroid spectacles On the right is a Large fly On the left is a series of circles an animals

70. 1.Fly is a test of gross stereopsis, useful for young children Fly should appear stand out from the page ,child is encouraged to pick up the tip of one of its wings between finger and thumb. In absence of gross stereopsis fly will appear as ordinary flat photograph. In book is inverted the targets will appear to be behind the plane of the page

71. 2.Circles comprise a graded series which tests fine depth perception. E ach of the nine squares contains four circles One of the circle in each square has a degree of diparity and will appear forward of the plane in presence of normal stereopsis 3.The Animals consist of three rows of animals , one of which appear forward of the plane of refrence .

72. Thank you