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Ocular motility and strabismus

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Ocular Motility and Strabismus for MBBS students

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Ocular motility and strabismus

  1. 1.  Visual axis—passes from the fovea, through the nodal point of the eye to the point of fixation (object of regard). The fovea is usually slightly temporal to the geometrical centre of the posterior pole so that visual axis cuts cornea slightly nasally.  Anatomical axis—passes from the posterior pole through the centre of the cornea. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 2
  2. 2.  Angle kappa—between anatomical and visual axis and it is about 5 degree. It is usually positive when nasally and negative when temporally. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 3
  3. 3. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 4
  4. 4.  The lateral and medial walls of the orbit are at an angle of 45 degree to each other. So the orbital axis forms an angle of 22.5 degree with both lateral and medial walls. In primary position of the gaze the visual axis forms about 23 degree with the orbital axis. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 5
  5. 5.  The eyeball is moved chiefly by six extrinsic muscles: four recti and two oblique muscles .  The four recti arise from a common tendinous ring that surrounds the optic canal and a part of the superior orbital fissure.  The four muscles are inserted into the anterior portion of the sclera, 6-8 mm posterior to the sclerocorneal junction (limbus). 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 6
  6. 6. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 7
  7. 7.  The distance from the midpoint of the rectus muscle tendons to the limbus is approximately 5.5 mm, 6.5 mm, 7.0 mm, and 7.5 mm for the medial, inferior, lateral, and superior rectus muscles, respectively. This configuration describes the spiral of Tillaux. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 8
  8. 8. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 9
  9. 9.  The superior oblique muscle arises from the sphenoid bone superomedial to the optic canal. It passes anteriorward, superior to the medial rectus, and through a cartilaginous pulley (the trochlea) attached to the frontal bone. The tendon is thereby directed posterolaterally, running inferior to the tendon of the superior rectus to insert into the posterior sclera.  The inferior oblique muscle arises from the maxilla at the anteromedial floor of the orbit, passes in a posterolateral direction, immediately inferior to the inferior rectus to insert into the posterior lower temporal quadrant of the globe close to the macula. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 10
  10. 10. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 11
  11. 11.  The superior oblique muscle is supplied by the trochlear nerve(4th), the lateral rectus by the abducent nerve(6th), and the others by the oculomotor(3rd) nerve.(LR6SO4) 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 12
  12. 12.  The horizontal lateral and medial rectus muscles are purely horizontal movers on the vertical Z- axis and have only primary action. The medial rectus is inserted 5.5 mm behind the nasal limbus and its sole action is adduction while the lateral rectus is inserted 7.0 mm behind the temporal limbus and its sole action is abduction. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 13
  13. 13.  The vertical superior and inferior rectus muscles run in line with orbital axis so forms an angle of 23 degree with visual axis. The superior rectus is inserted 7.5 mm behind the superior limbus and its primary action is elevation while secondary actions are adduction and intorsion. The inferior rectus is inserted 6.5 mm behind the inferior limbus and its primary action is depression while secondary actions are adduction and extorsion.6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 14
  14. 14.  The primary action superior oblique is intorsion and secondary actions are depression and abduction.  The primary action inferior oblique is extorsion and secondary actions are elevation and abduction. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 15
  15. 15. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 16
  16. 16.  The oculomotor (third cranial) nerve supplies all the muscles of the eyeball except the superior oblique and the lateral rectus muscles.  The oculomotor nerve supplies the levator palpebrae superioris and superior rectus (by its superior division) and the medial rectus, inferior rectus, and inferior oblique muscle (by its inferior division).  A parasympathetic communication arises from the nerve branch to the inferior oblique muscle.  This nerve enters the ciliary ganglion and synapses there.  Postganglionic parasympathetic nerve fibers pass from the ganglion to the eyeball through the short cilliary nerves, innervating the sphincter pupillae and ciliary muscle.  In the act of focusing the eyes on a near object the oculomotor nerves are involved in adduction (medial recti), accommodation (ciliary muscle), and miosis (sphincter pupillae).  Paralysis of the oculomotor nerve results in ptosis (paralysis of the levator), abduction (unopposed lateral rectus), and other signs. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 17
  17. 17.  The trochlear (fourth cranial) nerve supplies only the superior oblique muscle of the eyeball.  It emerges from the dorsum of the brain stem.  The trochlear nerve is tested by asking the subject to look downward when the eye is in adduction. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 18
  18. 18.  The abducent (sixth cranial) nerve supplies only the lateral rectus muscle of the eyeball.  It is bending sharply anteriorward across the superior border of the apical portion of the petrous part of the temporal bone.  This perhaps accounts for abducent involvement in almost any cerebral lesion that is accompanied by increased intracranial pressure. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 19
  19. 19.  The ciliary ganglion is the peripheral ganglion of the parasympathetic system of the eye. It is situated between the optic nerve and the lateral rectus .  The postganglionic parasympathetic fibers pass to the short ciliary nerves (which are branches of the ganglion) and supply the ciliary muscle and sphincter pupillae.  Postganglionic sympathetic fibers from the internal carotid plexus reach and pass through the ciliary ganglion. By way of the short ciliary nerves, the sympathetic fibers supply the dilator pupillae and blood vessels, as well as smooth muscle in the eyelid (superior tarsal muscle) and in the inferior orbital fissure (orbitalis). A sympathetic lesion (Horner syndrome) results in a small pupil (miosis) and mild ptosis . 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 20
  20. 20. a)ductions—movement of one eye only  Adduction(medial movement)  Abduction(lateral movement)  Supraduction(elevation)  Infraduction(depression)  Incycloduction(intortion)  Excycloduction(extortion) Agonist—it is the primary muscle moving the eye in any one direction Synergist—a muscle which act together with the agonist Antagonist—a muscle which acts in the opposite direction to the agonist Sherringtons law of reciprocal innervations—when the agonist contracts then the antagonist relaxes 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 21
  21. 21. b)versions—binocular movements in the same direction  Dextroversion(right gaze)  Levoversion(left gaze)  Supraversion(up gaze)  Infraversion(down gaze) Above 4 are the secondary positions of gaze  Dextro elevation  Dextro depression  Laevo elevation  Laevo depression Above 4 are tertiary position of gaze 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 22
  22. 22. Six cardinal position of the gaze-  Dextroversion  Laevoversion  Dextro elevation  Laevo elevation  Dextro depression  Laevo depression Yoke muscle—a muscle of one eye is paired with a muscle of the other eye while moving the eye into each of the six cardinal position of gaze  Dextroversion(LR of right eye & MR of left eye)  Dextroelevation(SR of right eye & IO of left eye) 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 23
  23. 23. Herings law of equal innervations—it says that during any conjugate eye movement equal and simultaneous innervations follows to the yoke muscle. So a paresis of one muscle is associated with over action of its yoke muscle or contra lateral synergist and it results in more secondary angle deviation in paralytic squint. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 24
  24. 24. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 25
  25. 25. c)vergences—binocular movements but in the opposite directions(convergence & divergence). Divergence is the turning outward while convergence is the turning inward of the both eyes. The convergence may be voluntary or reflux. The reflux convergences are of four types—  Tonic-due to inherent tone of medial recti  Proximal-due to psychological awareness of a near object 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 26
  26. 26.  Fusional-which is maintained by binocular single vision, so that similar images are projected onto the corresponding retina.  Accommodative-each dioptre of accommodation is accompanied by a constant increment in accomodative convergence, giving the AC/A ratio. This is the amount of convergence in prism dioptre (∆) per dioptre (D). The normal value is 3-5 ∆. This means that 1 D of accommodation is associated with 3-5 ∆ of accommodative convergence. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 27
  27. 27. d)supra nuclear eye movements—  Saccades--rapid, voluntary, refixating eye movements  Pursuits—smooth following movements to maintain vision on a slow moving object  Vestibulo-ocular movements—vestibular nystagmus in caloric test 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 28
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  31. 31.  it is the co-ordinated use of the two eyes to produce a single unified image. It is not present at birth but develops later with Clear vision in both eyes Co-ordination between both eyes in all directions of gaze Ability of brain to fuse a)simultaneous macular perception—ability to see two dissimilar images simultaneously and to super impose them b)fusion—ability to see the slightly dissimilar images formed in each eye and blended them into one. The fusional vergence may be decreased by fatigue or illness, converting a phoria to a tropia. It can be increased by orthoptic exercises. The normal values are  Convergence (adduction)—15 ∆ for distance and 25 ∆ for near. It controls exophoria  Divergence (abduction)-- 6 ∆ for distance and 12 ∆ for near. It controls esophoria  Vertical—2-3 ∆  Cyclovergence—about 2-3 degree c)stereopsis—depth perception by two eyes 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 32
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  34. 34.  Confusion—the simultaneous appreciation of two superimposed but dissimilar images caused by stimulation of corresponding points usually fovea by images of different objects. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 35
  35. 35.  a)physiological diplopia—it is normal phenomenon due to looking at a near object with attention directed to a distant object.  b)uniocular diplopia—when only one eye is open  Immature cortical cataract  Subluxated lens  Large iridectomy, iridodialysis(polycorea)  Retinal detachment  c)binocular diplopia—when both eyes are open  Paralysis of extra ocular muscle  Displacement of eye ball due to tumour/fracture  Mechanical restriction of eye movements(pterygium, symblepharon, thyroid ophthalmopathy  Decentred spectacles  Anisoconia (due to aphakic correction of one eye)  Congenital high anisometrpia  In case covergent squint uncrossed(homonymous) diplopia while in divergent squint crossed(heteronymous) diplopia 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 36
  36. 36.  a unilateral or bilateral reduction of vision without any organic ocular lesion. The most sensitive period of amblyopia to develop is first 6 months of life and after 6 years amblyopia usually does not occur. The types are Stimulus deprivation amblyopia(amblyopia exanopia)—caused by congenital cataract, leucoma, ptosis, occlusion Strabismic amblyopia Anisometropic amblyopia Isoametropic amblyopia(bilateral amblyopia) Meridional amblyopia—due to uncorrected astigmatism and it can be unilateral or bilateral. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 37
  37. 37. Diagnosis—  Visual acuity—a difference in BCVA of two or more lines between two eyes and visual acuity is good for a single letter than a row of letters.  Neutral density filters which decrease the visual acuity in normal/organic lesion of the eye but no decrease in case of amblyopia.  Grating (grid pattern) acuity often exceeds spatial (Snellen) acuity in amblyopia.  The visual fields and colour vision are normal in amblyopia. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 38
  38. 38. Treatment—can be treated up to 7-8 years of age in strabismic amblyopia and up to 11-12 years in anisometropic amblyopia.  Removal of opacity in the media  Full correction of refractive errors  Sound eye occlusion therapy—it may be total occlusion(both light and form sense occluded) or partial occlusion(only form sense occluded)  Number of days of occlusion equal to the number of years up to 6 years  Penalisation by atropine  Pleoptics and CAM stimulator to increase foveal fixation 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 39
  39. 39. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 40
  40. 40.  Suppression— it is the active inhibition by the visual cortex, of an image from one eye when both eyes are open. The stimulus for suppression includes diplopia, confusion and a blurred image resulting from astigmatism/anisometropia. The central foveal suppression of the deviated eye occurs in case of confusion while peripheral retinal suppression occurs in diplopia. Monocular suppression can leads to amblyopia while alternating suppression does not cause amblyopia.  Abnormal retinal correspondence (ARC)—in this the non corresponding retinal elements acquire a common subjective visual direction. The fovea of the fixating eye is paired with non foveal element of the deviated eye. It allows some binocular vision with limited fusion and frequently in small angle esotropia.6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 41
  41. 41. Motor adaptation to strabismus—this involves the adoption of the abnormal head posture and occurs in adults who cannot suppress or in children with binocular vision potential. The abnormal head posture is to maintain BSV and to eliminate diplopia. The head is turned in the direction of the action of weak muscle.  Horizontally face is turned to right or left  Vertically chin is elevated or depressed  Torsionally head is tilted to right or left shoulder 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 42
  42. 42. History—  Early age of onset requires surgery while later onset likely to be accommodative type.  Old photographs are important.  Intermittent squint suggests some degree of binocularity while in alternating squint both eyes have good vision.  Children with cerebral palsy have increased incidence of strabismus  Less gestational period, low birth weight  Family history 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 43
  43. 43. Visual acuity in preverbal child—  Occlusion of good eye is objected by child  Fixation test by 16 ∆ base-down prism over one eye and other eye is occluded.  Hundreds and thousands sweet test—if child is able to pick up small sweets at 33 cm then visual acuity is at least 6/24.  Brisk rotation test—in case of impaired vision the nystagmus does not stop after stopping the rotation.  Preferential looking test—Teller acuity cards (black strips of varying thickness) and Cardiff acuity cards (shapes of variable outlines)  Pattern visually evoked potential  Optokinetic nystagmus 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 44
  44. 44. Visual acuity in verbal child—  At 2 years pictures test (Kay pictures)  At 3 years single letter optotypes (Sheridan-Gardiner test)  At 4 years linear Snellen acuity test Tests for steriopsis—  Titmus fly and circles test  TNO test with red and green spectacles  Lang test  Frisby test 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 45
  45. 45. Base out prism test— it is to detect BSV in children who cannot perform the above mentioned stereo tests. A 20 ∆ base-out prism is placed in front of right eye so retinal image is moved temporally to cause diplopia.  Right eye will shift to left (right adduction) and left eye will shift to left (left abduction) in accordance with Hering law.  Left eye then will go to corrective right (left re adduction)  On prism removal both eyes will go to right  Left eye will make then left fusional movement 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 46
  46. 46. a) Worth four dots test—the patient wears red lens in right eye (only red colour visible) and green lens in left eye (only green colour visible). The patient is shown one red, two green and one white dot.  If all four lights are seen—normal/ARC (with deviated eye)  Two red lights—left eye suppression  Three green lights—right eye suppression  Two red and three green lights—diplopia 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 47
  47. 47. Tests for sensory anomalies Worth four-dot test a - Prior to use of glasses b - Normal or ARC c - Left suppression Bagolini striated glasses a - Normal or ARC b- Diplopia c - Suppression d - Right suppression e - Diplopia d - Small suppression scotoma 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 48
  48. 48. b) Bagolini striated glasses—to convert a point light source into a line. Two lenses are placed at 45 and 135 degree in front of each eye and the patient fixates a point light source.  If an X- is visible then the patient is either orthophoric or ARC (if strabismic)  It two line do not cross then diplopia  If one line only then other eye is suppressed  If a small central gap in one line then central macular suppression 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 49
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  52. 52. c) After image test—this test demonstrates the visual direction of the foveae. The one fovea is stimulated by vertical bright flash light and other fovea is stimulated by horizontal flash light. The patient is asked to draw the relative positions of the after image. Results are  If two images cross each other then normal retinal correspondence  If two images do not cross each other then ARC  If esotropia with ARC the horizontal image (if presented to right eye) is seen to the left and reversed in exotro6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 53
  53. 53. Synaptophore—it is an instrument for assessing strabismus and quantifying binocular vision. It has two cylindrical tubes and a +6.5 D lens in each eyepiece. This optically sets the testing distance at about 6 meters. The different pictures are inserted into the slide carriers. It gives the grades of binocular vision  Simultaneous perception (first grade)—two dissimilar images are shown like a bird and a cage, then the patient is asked what he sees. If two pictures are not seen simultaneously then either suppression or significant amblyopia.  Fusion (second grade)—the ability of two eyes to produce a composite picture from two similar pictures each of which is incomplete in one small different detail.  Steriopsis (third grade)—depth perception by the superimposition of two pictures of the same object which have been taken from slightly different angles.6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 54
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  56. 56.  Hirschberg corneal reflection test (1mm =70 deviation)—a rough objective estimation of the angle of squint. A torch light is shone into the patients eyes at a arms distance. Each 1 mm difference is equal to 7 degree/15 ∆. If reflex is at pupillary border then angle is about 15 degree and if at the limbus then angle is about 45 degree. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 57
  57. 57. Hirschberg test • Rough measure of deviation • Note location of corneal light reflex Reflex at border of pupil = 15 Reflex at limbus = 45 • 1 mm = 7 or 15 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 58
  58. 58. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 59
  59. 59.  Krimsky prism reflex test—the prisms are placed in front of the fixating eye until the corneal light reflexes are symmetrical. It measures only manifest deviation but not latent deviaton. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 60
  60. 60.  Prism bar cover test(PBCT)—10 deviation=2 prism dioptres  Perimeter/tangent screen  Synaptophore 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 61
  61. 61. 1. Cover tests--  Cover-uncover test—by far the most accurate assessment of a deviation is with cover tests. The tropias can be differentiated from phorias. The cover and uncover test has two parts  Cover test to detect a hetrotropia. It should be done both for near and distance. If right deviation is suspected then left eye is covered and movement in right eye is noticed. No movement means orthophoria/lefty heterotropia. Adduction of right eye means exotropia while abduction of right eye means esotropia. Down movement means hypertropia and up movement means hypotropia. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 62
  62. 62.  Uncover test to detect a hetrophoria. It should be done both for near and distance. The examiner covers the right eye uncovers it after a few seconds. No movement means orthophoria. Adduction of right eye indicates exophoria while abduction indicates esophoria. Up/down movements indicate vertical phorias. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 63
  63. 63. Cover tests Cover test detects heterotropia • Prism cover test measures total deviatio Alternate cover test detects total deviation Uncover test detects heterophoria 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 64
  64. 64. 2. Alternate cover test—it interrupts binocular fusion and reveals total deviation (phoria + tropia). The eye is occluded for 2 sec then other eye is occluded for 2 sec and then repeated several times. After the cover is removed, then smoothness and speed of recovery is noted as the eyes return to their pre dissociated state.  Patient with heterophoria will have straight eyes before and after the test  Patient with heterotropia will have a manifest deviation 3. Prism cover test—it precisely measures the angle of deviation. The prisms of increasing strength are placed in front of one eye with apex in the direction of the deviation. The alternate cover test is continuously performed and stronger prisms are brought in till the end point is reached with no further eye movement. At this point the angle of deviation is equal to the strength of prism. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 65
  65. 65. a) Maddox wing— it dissociates the eyes for near fixation (1/3 m) and measures heterophoria. The right eye sees only a white vertical arrow and a red horizontal arrow whereas left eye sees horizontal and vertical rows of numbers.  The horizontal deviation is measured by asking the patient at which number white arrow points  Vertical deviation is measured by red arrow  Cyclophoria is determined by asking the patient to rotate the red arrow until it is parallel with the horizontal row of numbers 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 66
  66. 66. b) Maddox rod—consists of fused cylindrical red/white glass rors which converts a point light source into a line 90 degree to the axis of the rods.  Rod is placed in the right eye, this dissociates the two eyes so that line is seen by right eye and point source by left eye and in case of squint they are not superimposed  Amount of deviation is measured by superimposing two images with the help of prism (apex towards the deviation)  This test cannot differentiate phoria from tropia  Ocular movements (versions and ductions) are checked 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 67
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  70. 70.  Near point of convergence (NPC)—the nearest point on which the eyes can maintain fixation and it is measured with the RAF rule which rests on patient`s cheeks. The target is slowly moved along the rule towards the patient until one eye loses fixation and drifts laterally (objective NPC). The subjective NPC is the point at which patient reports diplopia. The normal NPC should be nearer than 10 cm.  Near point of accomodation (NPA)—the nearest point on which the eyes can maintain clear focus and also measured by RAF rule. At the age of 20 years it is 8 cm and at 50 years it is 46 cm. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 71
  71. 71.  Refraction under cyclopegia—to check hypermetropia, astigmatism, anisometropia, myopia  Fundoscopy—to rule out macular scarring, optic disc hypoplasia, retinoblastoma 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 72
  72. 72. It is the misalignment of the two eyes while orthophoria is the perfect ocular alignment without any effort. When a child develops squint, the following changes occurs  The fovea of the squinting eye is suppressed to avoid confusion  Diplopia occurs because non corresponding retinal elements receive same image  To avoid diplopia the patient will develop either peripheral suppression of the squinting eye or ARC  If suppression occurs this will lead to strabismic amblyopia 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 73
  73. 73. A)apparent squint(pseudo strabismus) B)latent squint(heterophoria) C)manifest squint(hetrotropia)  Concomitant (non paralytic) squint  Non concomitant (paralytic) squint 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 74
  74. 74. Apparent squint (pseudo strabismus)-- it can be pseudo-esotropia or exotropia. a) Pseudo-esotropia—  Epicanthic folds  Short inter pupillary distance  Negative angle kappa—it is the angle between visual and anatomical axes. Normally fovea is slightly temporal so when a light is shone onto the cornea, then reflex will be just nasal to the centre of the both eyes. It is termed as positive angle of kappa but when fovea is nasal (high myopia, ectopic fovea) then angle kappa will be negative. b) Pseudo-exotropia—  Wide interpupillary distance  Positive angle kappa 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 75
  75. 75. Pseudo-deviations Pseudo-esotropia Epicanthic folds Short interpupillary distance Negative angle kappa Pseudo-exotropia • Wide interpupillary distance • Positive angle kappa 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 76
  76. 76. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 77
  77. 77.  the eye has a tendency to deviate but prevented by the fusion mechanism to have binocular single vision.Under stress or when fusion is interrupted, the deviation becomes manifest.  Exophoria—eye tends to deviate outwards  Esophoria—eye tends to deviate inwards  Hyperphoria—eye tends to deviate upwards  Cyclophoria—tortional deviation  In general esophoria more in hypermetropes and exophoria more in myopes & presbyopes 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 78
  78. 78. Symptoms—  Blurred vision  Headache and eye ache  Intermittent diplopia Diagnosis—  Cover test  Maddox rod test  Prism vergence test  Synaptophore 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 79
  79. 79. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 80
  80. 80. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 81
  81. 81.  Smaller degree –not treated  Errors of refraction corrected  Orthoptic exercise to increase fusion  Exercises with adverse prism(base of the prism towards the direction of deviation)  Relief of symptoms with prism(apex of the prism towards the direction of deviation)  Operation is rarely indicated 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 82
  82. 82.  it is the dissociation of the eyes where the angle of deviation remains the same in all directions of gaze. The causes are  Poor vision in one eye due to refractive errors, media opacity, retinal & optic nerve diseases  Disturbances of ocular muscle insertion/mal development  Dissociation between accommodation and convergence relationship(in hypermetropes more accommodation causing convergent squint and in myopes less accommodation causing divergent squint  Decomensated heterophoria leading to heterotropia  Central causes are cerebral palsy, mental retardation, deficient fusion 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 83
  83. 83.  in about 85% cases one eye takes up fixation and other eye becomes squinting. It may be  Convergent—one eye deviates inwards and caused by amblyopia(more), hypermetropia, esophoria, orbital asymmetry  Divergent—one eye deviates outwards and caused by amblyopia(less), myopia, secondary divergent squint(blind eye at rest), over correction of convergent squint  Vertical—rare 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 84
  84. 84. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 85
  85. 85. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 86
  86. 86. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 87
  87. 87. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 88
  88. 88. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 89
  89. 89.  when one eye fixes the other eye deviates and either of the eyes can adopt fixation alternately.  In this the visual acuity remains normal/near normal in both eyes.  There is no diplopia as the image formed by the deviating eye is suppressed by the brain. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 90
  90. 90. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 91
  91. 91. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 92
  92. 92.  No symptoms/no diplopia  In case of monocular squint the visual acuity is poor(strabismic amblyopia)  No limitation of ocular movements  Primary angle of deviation is equal to secondary angle of deviation Primary angle—the deviation of the squinting eye when other eye is fixed Secondary angle—the deviation of the normal eye under cover when squinting eye is fixed 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 93
  93. 93. Accomodative type  Refractive (fully accommodative/partially accommodative)  Non-refractive (with convergence excess/accommodation weakness)  Mixed accomodative 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 95
  94. 94. Non-accomodative  Essential infantile  Microtropia  Basic—no significant refractive error with equal deviation for near and distance. It is treated surgically.  Convergence excess-- no significant refractive error with orthophoria/small esophoria for distance and esotropia for near. Normal or low AC/A ratio with normal near point of accommodation. Treated with bilateral medial rectus recession.  Divergence insufficiency—occurs in young healthy adults with intermittent or constant esotropia for distance. Full abduction bilaterally and treated prisms/bilateral lateral rectus resections. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 96
  95. 95.  Divergence paralysis—at any age and difficult to differentiate with uni/bilateral lateral rectus palsy but comitant. The esotropia is unchanged or decrease on lateroversion (unlike a 6th nerve palsy). Neurological causes such as head trauma, ICSOL and cerebrovascular accidents may be present.  Sensory esotropia—caused by unilateral cataract, optic nerve atrophy/hypoplasia, toxoplasma retinochroiditis and retinoblastoma.  Consecutive esotropia—following surgical overcorrection of an exodeviation.  Acute onset  Cyclic oculomotor spasm—usually hysterical an intermittent phenomenon or occasionally with trauma/posterior fossa tumour. During attack esotropia with pseudo-myopia due to accommodative spasm and bilateral miosis. Treated with cycloplegics 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 97
  96. 96.  Refractive accommodative esotropia—it is due to high hypermetropia (between +4 and +7 D) and AC/A ratio is normal. The magnitude of deviation is usually <10 ∆ and varies little between distance and near. The fully accommodative type is completely eliminated by optical correction of hypermetropia while partial type is reduced but not eliminated by the correction of hypermetropia. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 98
  97. 97.  Non-refractive accommodative esotropia—it is associated by high AC/A ratio. In this one unit increase of accommodation is accompanied by a disproportionately large increase of convergence in the absence of significant hypermetropia. a) Convergence excess type—characterised by high AC/A ratio due to increased convergence while accommodation is normal. Normal near point of accommodation. The eyes are straight for distance but esotropia for near. b) Hypoaccomodative type—high AC/A ratio due to decreased accommodation so extra effort of accommodation is used for near with more convergence. The near point of accommodation is increased.6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 99
  98. 98.  Mixed accommodative esotropia— hypermetropia and high AC/A ratio may coexist, so esotropia for distance which increases >10 ∆ on near fixation. The distant deviation is usually corrected by spectacles but for near esotropia patient should wear bifocals. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 100
  99. 99. H/O  age of onset, acute illness,  family history,  intermittent or constant,  unilateral/alternating, diplopia  head posture to differentiate from paralytic squint examination—  visual acuity  refraction under atropine(to find out refractive errors)  ocular motility limitation  foveal or extra foveal fixation  anterior segment & fundus  cover test to find out uniocular/alternating type6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 101
  100. 100.  Hirschberg corneal reflection test(1mm=70 deviation)—at papillary margin=150 and at limbus=450  Krimsky prism reflex test  Prism bar cover test(PBCT)—10 deviation=2 prism dioptres  Perimeter/tangent screen  Synaptophore  worth 4 dot test 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 102
  101. 101.  The aim is to make eye straight and to ensure binocular single vision. The prognosis decrease after 6 years and in adults the surgical correction is purely for cosmetic reason(4 Os)--- 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 103
  102. 102.  Optical correction of refractive error--in children less than 6 years a full cycloplegic refraction revealed on retinoscopy should be prescribed. In fully accommodative type esotropia this will control the deviation both for near and distance. After the age of 8 years the retinoscopy should be done without cycloplegia and maximum plus glasses that can be tolerated are prescribed. The executive type bifocals are prescribed in case of mixed accommodative type. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 104
  103. 103.  Miotic therapy—used for short term in children with accomodative esotropia due to high AC/A ratio, who will not wear spectacles. 0.125% ecothiopate iodide e. d. once/ day or 4% pilocarpine qid for 6 weeks. This will cause more peripheral accommodation directly by ciliary muscle so less accommodative effort will be used by patient for near vision and thereby less accommodative convergence. 2.5% phenylepherine b d can be used with ecothiopate to decrease iris cyst formation.  Occlusion therapy to treat amblyopia  Orthoptic exercises  Operative procedures-- when deviation is not fully corrected by spectacles.6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 105
  104. 104. a)weakening procedures  Recession--it slackens a muscle by moving its insertion towards its origin. It can be done for any extraocular muscle except the superior oblique. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 106
  105. 105.  Marginal myotomy  Myectomy--severing the muscle from its insertion without reattachment. Commonly used for overacting inferior oblique and sometimes for contracted rectus.  Tenotomy 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 107
  106. 106.  Fadens procedure(posterior fixation suture)--to decrease the pull of the muscle in its field of action without affecting its primary position. The belly of the muscle is sutured with a non absorbable suture a few mm behind to its insertion. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 108
  107. 107. b)strengthening procedures  Resection—to shorten a muscle to enhance its effective pull.  Advancement—to bring muscle nearer to the limbus.  Tucking (plication)—the muscle or its tendon is reserved to enhance the action of SO muscle in congenital 4th nerve palsy. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 109
  108. 108.  1 mm resection/recession of MR corrects 30 of deviation  1 mm resection/recession of LR corrects 20 of deviation  Medial rectus should not be recessed more than 5.5 mm as this will cause convergence deficiency and should not be resected more than 5.5 mm as this will cause retraction of the globe and narrow palpebral fissure  The resection and recession limits for lateral rectus are 7 mm.  It is preferred to operate on elevators rather than depressors 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 110
  109. 109. Convergent squint—  MR recession & LR resection(in squinting eye)  Bimedial recession(in both eyes) Divergent squint—  LR recession & MR resection(in squinting eye)  Bilateral recession(in both eyes) 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 111
  110. 110. Essential infantile esotropia— An idiopathic within first 6 month of life with no significant refractive error and no ocular movement limitation.  The angle is usually large >30 ∆  Alternating fixation in primary gaze and cross fixation in side gaze so right eye is used in left gaze and left eye is used in right gaze.  Nystagmus latent or manifest type and usually horizontal  Inferior oblique over action may present  Dissociated vertical deviation in 80% cases by the age of 3 years. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 112
  111. 111. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 113
  112. 112. Differential diagnosis—  Congenital bilateral sixth nerve palsy  Sensory esotropia due to organic eye disease  Nystagmus blockade syndrome in which convergence dampens a horizontal nystagmus  Duanes syndromes type I & III  Mobius syndrome  Strabismus fixus (due to fibrosis) Management of essential infantile esotropia—the eyes should be surgically aligned by the age of 12 months but only after amblyopia or significant refractive error have been corrected. Any associated over action of the inferior oblique should be corrected. Treatment for amblyopia (develops in 50% cases) and DVD should be done. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 114
  113. 113.  Dissociated vertical deviation (DVD)— under cover up-drift with excyclodeviation of the eye but when cover is removed the affected eye moves down without corresponding down movement in the other eye. So DVD does not obey Hering law. It is treated by superior rectus recession with or without a Faden procedure and/or inferior oblique anterior transposition. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 115
  114. 114. Microtropia (monofixation syndrome)—it may be primary or after surgery for a large deviation.  Anisometropia in nearly all cases, commonly with hypermetropia or hypermetropic astigmatism  Very small angle less than 8 ∆ which may or may not be detected with cover test  Central suppression scotoma of the deviating eye prevents confusion  Bagolini striated glasses show a cross with a gap in the oblique line 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 116
  115. 115.  4 ∆ base-out prism is placed in front of the normal eye, the image is moved from the fovea to the parafoveal temporal point resulting in a re-fixation movement. No movement will occur in the microtropic eye since the image is moved within the central suppression scotoma.  Treated with spectacle correction of anisometropia and occlusion for amblyopia but bifoveal fixation never occurs. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 117
  116. 116. I. Constant types  Congenital exotropia—present at birth with large and constant angle with normal refraction. DVD and neurological anomalies may be present. Treated with bilateral rectus recessions combined with one or both medial recti resection.  Sensory—due to monocular/binocular impairment of vision in children more than 5 years or in adults.  Consecutive—following over correction of an esodeviation II. intermittent types—present around 2 years  Basic—deviation same for distance and near  Convergence weakness—in older children and adults. The angle of deviation is greater for near.  Divergence excess-- The angle of deviation is greater for distance. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 118
  117. 117.  It is the misalignment of the visual axis as a result of paresis/paralysis of one or more extra ocular muscles.  The angle of deviation varies in different directions of the gaze. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 119
  118. 118. a) Lesions affecting cranial nerves (neurogenic)—  Supranuclear or internuclear  Nuclear lesions—cerebrovascular diseases, infections(encephalitis, meningitis, peripheral neuritis, neurosyphilis), neoplasms  Lesions of nerves—congenital hypoplasia, head injury, meningitis, cavernous sinus thrombosis  Vascular lesions—hypertension, diabeties, haemorrhage, thrombosis, atherosclerosis  Direct or indirect trauma to nerves  Carbon monoxide poisoning ,diphtheria toxin, alcoholic and lead neuropathy  Demyelinatig lesions like multiple sclerosis 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 120
  119. 119. b)Lesions of extra ocular muscles (myogenic)—  Congenital absence or hypoplasia of muscles  Injury of muscles  Inflammatory lesions like myositis after influenza, measles etc  Myopathies, myasthenia gravis, thyroid diseases 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 121
  120. 120.  Crossed (divergent squint)/uncrossed diplopia (convergent squint)  False orientation of the objects  Vertigo and nausea  Visual acuity is normal in both eyes  Secondary angle of deviation is more than the primary angle of deviation  Restricted ocular movement in the direction of action of paralysed muscle  Compensatory head posture(head turned in the direction of action of paralysed muscle) 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 122
  121. 121. a) Total ophthalmoplegia—both intrinsic and extrinsic muscles are paralysed. The clinical features are  Slight proptosis and divergent position(anatomical rest position)  Ptosis  No movement  Fixed dilated pupil  No reaction to light and accommodation b) External ophthalmoplegia—  Paralysis of only extrinsic muscles  Papillary reaction and accommodation normal 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 123
  122. 122. c) Oculomotor nerve (3rd) palsy—  Ptosis due to weak LPS function  Divergent and slightly down eye ball due to unopposed action of LR(6th) and SO(4th)  Intorsion of eye ball on attempted downgaze due to SO action  Ocular movements restricted in all directions except outward(LR action)  Pupil dilated and not constricts to light or convergence 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 124
  123. 123. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 125
  124. 124. d) Trochlear nerve(4th) palsy—  Trauma is the most common cause  Abnormal head posture(chin depressed, head tilt & face turned to the normal side)  Diplopia more in the down gaze  Eye ball deviates upward and inward(ipsilateral hypertropia)  Extortion of the globe  Restricted downward and inward movement  Bielschwsky three steps test for diagnosis of 4th nerve palsy 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 126
  125. 125. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 127
  126. 126. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 128
  127. 127.  The most common type of palsy and commonly caused by raised ICT  Eye ball convergent  Defective abduction  Face turned in the field of action of the paralysed muscle 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 129
  128. 128. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 130
  129. 129. Sequelae of extra ocular muscle palsy  Over action of contralateral synergist (yoke muscle)  Contracture of ipsilateral antagonist  Inhibitionalpalsy of the contralateral antagonist a) Example of right lateral rectus palsy  Over action of left medial rectus  Contracture of right medial rectus  Inhibitional (secondary) palsy of left lateral rectus b) Example of superior oblique palsy  Over action of left inferior rectus  Contracture of right inferior oblique  Inhibitional palsy of left superior rectus 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 131
  130. 130. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 132
  131. 131. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 133
  132. 132.  Diplopia charting  Hess screen chart  Worth 4 dots test  Forced duction test(FDT)  X-ray skull  CT scan(orbit & brain)  MRI scan  Blood sugar level  Thyroid function tests  Tensilon test for myasthenia 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 134
  133. 133. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 135
  134. 134. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 136
  135. 135.  Occlusion therapy  Relieving prism  Observation for 6 months  Recession of contra lateral synergist  Muscle transposition surgery  Botulinum toxin injection to treat the antagonist muscle 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 137
  136. 136.  Hummelsheim procedure—the medial rectus is recessed and lateral halves of superior and inferior recti are disinserted and reattached to superior and inferior margins of paretic LR muscle. To avoid postoperative anterior segment ischaemia the MR recession may be replaced by botulinum toxin injection.  Jensen procedure—the splited lateral halves of superior and inferior recti are sutured with a non absorbable material superior and inferior margins of paretic LR muscle with recession/botulinum toxin injection of MR. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 138
  137. 137. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 139
  138. 138. Surgery for superior oblique palsy—the surgery is done in cases with abnormal head posture and diplopia unresponsive to prisms.  Congenital cases with large hypertropia in primary position are treated with SO tucking.  Acquired small hypertropias are treated by ipsilateral IO weakening.  Acquired moderate to large hypertropias are treated by ipsilateral IO weakening combined with ipsilateral SR weakening and/or contralateral IR weakening.  Acquired pure excyclotropias without hypertropias are treated by Harada-Ito procedure which involves splitting and anterolateral transposition of the lateral half of the superior oblique tendon. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 140
  139. 139. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 141
  140. 140.  Adjustable sutures—indicated when a precise outcome is essential and conventional procedures are unpredictable; for example acquired vertical deviations with thyroid myopathy, after blowout fracture, 6th nerve palsy, adult exotropia etc. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 142
  141. 141. Botulinum toxin chemodenervation—it causes temporary paralysis of an extra ocular muscle and can be used in  To determine LR function in 6th nerve palsy where MR contracture prevents abduction. So botulinum toxin is injected into the belly of overacting MR under electromyographic guidance  To determine the risk of postoperative diplopia and to assess the potential of BSV 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 143
  142. 142. 6/17/2015Dr. Mohd Najmussadiq Khan, M. S. (Ophth) 144

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