Mansoura University, Faculty of Medicine Strabismus Lecture Notes PDF

Mansoura University, Faculty of Medicine Mansoura – Manchester Programme for Medical Education  Prof. Manal Kasem Prof. Ophthalmology MOC; Mansoura University Name of instructor Contact information: e-mail: [email protected] Mobile: 01006264016 Academic hours: ...

Mansoura University, Faculty of Medicine Mansoura – Manchester Programme for Medical Education  Prof. Manal Kasem Prof. Ophthalmology MOC; Mansoura University Name of instructor Contact information: e-mail: [email protected] Mobile: 01006264016 Academic hours:  Important Note The information included in this presentation are not the only source for this topic and you should explore other valuable references in order to satisfy the ILOs of this topic. Content of lecture Def.of strabismus Types of strabismus Diagnosis of a case of strabismus Management a case of strabismus Def. of amblyopia Types of amblyopia treatment of amblyopia quizzes Learning outcomes At the end of this lecture, the student should be able to:.to know different types of strabismus.to know Broad lines of management a case of strabismus.to define amblyopia.to know management of amblyopia.answer the quiezzes  By Prof. Manal Kasem Prof. Ophthalmology MOC Mansoura University Definitions Optic axis: A line joining the center of the cornea, lens and retina. Visual axis: A line between the macula and the object of regard. Muscle axis: A line between the origin and the insertion of the muscle. Optic axis Muscle axis Orthophoria : It is a perfect equilibrium of oculomotor apparatus No latent strabismus or manifest Strabismus. Orthotroria : It is an equilibrium of oculomotor apparatus (No manifest strabismus) but may be thereis alatent strabismus. Strabismus: It is the condition in which the visual axes of both eyes are not directed to the same object of regard.  Orthotropia Esotropia Exotropia Hypertropia Hypotropia  Extraocular muscles (6 muscles) Four recti: superior, inferior, medial and lateral rectus Two obliques: superior and inferior oblique Insertion of extra-ocular muscles Nerve Supply (3 cranial nerves) 3rd , 4th , and 6th Oclumotor, Trochlear , and abducent S.R. I.R. III cranial nerve M.R I.O L.R. 6th cranial nerve S.O. 4th cranial nerve All EOM supplied by III (Oclumotor) Except S.O (4th) and L.R (6th). Actions of extra ocular muscles X-Y-Z axes  Actions of extra ocular muscles Horizontally acting muscles: Medial rectus Adduction. Lateral rectus Abduction. Vertically acting muscles Superior rectus  Elevation.  Adduction.  Intortion.. Superior rectus Superior rectus (A) Primary (B)Abduction (C) Adduction Position Elevation Elevation Intorsion Incyclotorsion Adduction Adduction Mean elevator in abduction Elevation  Vertically acting muscles Inferior rectus  Depression  Adduction  Extortion  Inferior rectus (A) Primary (B)Abduction (C) Adduction Position Extorsion Depression Depression Adduction Extorsion Mean Depressor in abduction Depression Adduction  Oblique muscles Superior Oblique muscle  Intorsion  Depression  Abduction Superior oblique muscle also is unique Superior Oblique muscles (A) Primary (B)Adduction (C) Abduction Position Depression Intorsion (Mean depressor in Intorsion Depression adduction) Depression Abduction (reading position) We use this action in our daily lives Inferior Oblique muscle  Extortion  Elevation  Abduction (A) Primary (B)Adduction (C) Abduction Position Elevation Abduction Extorsion Extorsion Extorsion Elevation (Mean elevator in Elevation Abduction adduction)  Eye movements A. Ductions  Monocular movements adduction, abduction, elevation, depression intorsion and extorsion. B. Versions  Binocular movements: the two eyes move synchronously and symmetrically in the same direction. C.Vergence  Binocular eye movements. Convergence (both eyes move inwards to look at a near object) Divergence (both eyes move outwards to look at a far object).  Version movements Binocular movements. Dextrocycloversion Elevation Laevocycloversion Dextroversion Laevoversion Depression  Vergence movements  Convergence.  Divergence Types of convergence. Tonic convergence. Accommodative convergence. Diagnostic 9 positions of gaze  Binocular single Vision It is the ability of the brain to see one image of one object by using two eyes Pre – requisites  Identical retinal images  Normal retinal correspondence  Intact fusion center and visual pathways  Binocular single vision Prerequistes :  The image from both retinae: Should be nearly identical (size, shape, clarity, brightness etc.) i.e. no marked anisometropia.  Extraocular muscles: Normal retinal corresponding. This fine adjustment requires good extraocular muscle function.  Normal visual pathway and C.N.S.: Normal fusion centre. Grades of binocular single vision: Grade I (Simultaneous perception) Grade II: (Fusion) Grade III (Stereopsis) Synoptophore Double vision Binocular Diplopia Double vision  Adaptive phenomena to double vision A) Sensory adaptation 1-Suppression 2- Abnormal retinal correspondence 3- Eccentric fixation B) Motor adaptation 1-Latent squint 2-Blind spot syndrome 3-Abnormal head posture  1. Suppression + amblyopia  Mainly in children  an active inhibition of vision in the squinting eye by visual cortex.  A temporary phenomenon occurring only when both eyes are open, if the fixing eye is covered, the suppression stops immediately and the squinting eye takes up fixation.  Prolonged suppression of squint eye Strabismic ambylopia 2. Abnormal retinal correspondance (ARC) The fovea of the normal eye and an extrafoveal point (which is normally non corresponding) of the squinting eye will develop a common visual direction. 3. Eccentric fixation: The extrafoveal point in squinting eye is maintained to be the fixation point even when the normal eye is covered B) Motor adaptation 1-Latent squint 2-Blind spot syndrome 3-Abnormal head posture Components of Abnormal head posture According to the paralyzed muscle. i. Face turn in a case of horizontal recti paralysis. ii. Chin elevation or depression in a case of vertical recti paralysis. iii. Head tilt in a case of oblique muscle paralysis. Strabismus Classification Apparent strabismus (pseudostrabismus) ‫كاذب‬ Latent strabismus (heterophoria) ‫خفى‬ Manifest strabismus (heterotropia): ‫حقيقى‬  Paralytic  Comitant  Strabismus Apparent True Manifest Latent Paralytic Concomitant 3rd ,4th ,and 6th Convergent Divergent Apparent Etiology 1. Apparent convergent squint: Epicanthus Small interpupillary distance. Pseudoesotropia 2. Apparent divergent squint:  Large interpupillary distance (large angle α). Pseudoexotropia Diagnosis: Corneal light reflex test: normally centered. Cover test: no movement occurs.  It is tendency of the eye to deviate. Etiology: 1. Uncorrected errors of refraction: Hypermetropia Myopia 2. Congenital weakness of one or more of extraocular muscles. Types: Esophoria, exophoria, hyperphoria, hypophoria. Clinical picture:  Muscular asthenopia: eye strain, headache and lacrimation.  Occasional diplopia: running letters during reading.  Patient or his parents may complain that the child's eye deviates when tired or not concentrating.  Cover test.  Maddox rod test.  Maddox wing test.  Diagnosis By Maddox rod test  Exophoria Esophoria Possible results of Maddox rod test Treatment: Compensated cases with no symptoms  no treatment. Correction of error of refraction Surgery: indicated when symptoms are not relieved by glasses. A. Paralytic strabismus Definition: Deviation of the eye due to paralysis of one or more of the extraocular muscles. Etiology: lower motor neurone lesion (LMNL). 1. Nuclear lesions 2. Nerve lesions 3. Muscle lesions  Paralytic Strabismus Symptoms 1- Diplopia 2- Limitation of movement 3- Vertigo, nausea 4- Compensatory head posture Signs 1. Ocular deviation:  Paralyzed muscle loses its tone.  The antagonist draws the eye towards it (i.e. the eye deviates to the opposite direction of the paralyzed muscle). 2. Limitation of movement of the eye in direction of action of the paralyzed muscle. 3. Angle of deviation: variable in different directions of gaze and also changes depending on which eye is fixing: Variable angle in different direction of gaze  Primary angle of deviation: Angle when the patient is fixing with the normal eye.  Secondary angle of deviation: The angle when the patient is trying to fix with the squinting eye (normal eye is covered).  Secondary > Primary due to excessive impulses sent by the brain to the paralyzed muscle to contract. The same excessive impulses also reach the normal yoke muscle in the other eye producing a larger deviation. Primary deviation Secondary deviation 4. Binocular diplopia: it is maximum when the patient looks at an object situated in the direction of action of the paralyzed muscle and decreases in the opposite direction. 5. False projection: wrong estimation of the sites of objects. 6. Compensatory head posture: abnormal head position adopted to avoid diplopia. The head is turned in direction of action of paralyzed muscle. Face turn Compensatory head Compensatory chin elevationand head tilt tilt  Examples  3rd nerve palsy.  4th nerve palsy.  6th nerve palsy. Third nerve palsy:  Ptosis.  Deviation of the eye down (superior oblique) and out (lateral rectus).  Limitation of movement in the direction of action of the involved muscles.  No diplopia (ptosis).  Dilatation of the pupil, paralysis of accommodation. Fourth nerve palsy: If the leftt superior oblique is affected, the clinical picture will be. 1. Deviation: the eye is deviated upwards and slightly inwards with extortion. 2. Limited depression in adduction (much discomfort on going downstairs). 3. Binocular diplopia on looking down and in. 4. Abnormal head posture: chin depression with head tilt to opposite side. Sixth nerve palsy (lateral rectus palsy): If the right lateral rectus is affected, the clinical picture will be:- Esotropia of the right eye. Limitation of movement when the patient moves his eye to the right. The angle of deviation is large when the patient looks to the right side. The angle of squint is large when the right eye is fixing. Diplopia most marked when the patient looks to the right. Face turn to the right. Combination of muscle palsy:-  Ophthalmoplegia = ocular muscle palsy.  External ophthalmoplegia = paralysis of extraocular muscles.  Total ophthalmoplegia = paralysis of extraocular and intraocular muscles.  Superior orbital fissure syndrome = paralysis of 3,4,6 + ophthalmic nerve ( anaesthesia).  Orbital apex syndrome = paralysis of 3,4,6 + ophthalmic + optic nerve (optic atrophy). Treatment:  Treatment of the cause.  Surgery: wait for 6 months before surgery for spontaneous nerve regeneration then reassess ocular motility: a. Strengthen the weak paretic muscle by resection and weaken the direct antagonist by recession. b. With transposition of healthy non-paralyzed muscles.. B. Concomitant strabismus It is manifest squint in which the visual axes of the 2 eyes are not directed to the same object and they maintain their abnormal relation in all directions of gaze.  Concomitant strabismus Etiology: obstacles that interfere with the development of binocular single vision. 1. Refractive causes (uncorrected errors of refraction) Hypermetropia Myopia  2. Non-refractive causes: Congenital Sensory  Sequelae of concomitant squint (sensory adaptation) 1. Suppression: the brain neglects the image of the squinting eye 2. Amblyopia: visual acuity in the suppressed eye starts to deteriorate permanently. 3. Eccentric fixation: occurs in some cases of amblyopia when the patient uses a parafoveal area for fixation (pseudo macula).  1- Infantile congenital esotropia Presentation: within the first 6 months of life Examination reveals: i. Angle of deviation is usually large. ii. Fixation is usually alternating. iii. Refractive error is normal for the age of the child (not excessively hypermetropic). Management: i. Refractive errors and amblyopia treated first. ii. Eyes are aligned surgically, usually at the age of 12 months. Congenital esotropia Post surgery 2- Refractive (accommodative) esotropia It is associated with activation of the accommodative reflex in response to excessive hypermetropia.  At age 2-3 yrs.  Variable angle increasing at near.  High hypermetropia. Fully Accommodative esotropia Management of accommodative esotropia Glasses Amblyopia Surgery therapy Types of surgery: 1. Weakening procedures = recession. 2. Strengthening procedures = resection. 3. Muscle transposition. Hummelsheim Jensen procedure Tests of importance: Cover uncover Cover tests Alternate cover Following movement Ocular movements Corneal reflection test Order movement Worths 4 dots Maddox rod test Synoptophore  Evaluation of a case of strabismus 1- History 1- Age of onset. 2- Type of onset (sudden ,gradual) 3- Family history 3- Variability 5- Intermittent or constant 6- Diplopia 2-Unilateral or alternating 1.Cover test. 2.Visual acuity. Cover tests Alternating Alternating  3 -Concomitant or paralytic 1. Ocular motility 2. Angle of deviation (1ry and 2ry angle of deviation) Concomitant Paralytic 3-Convergent or divergent Corneal reflection test Convergent 1. Accommodative 2. Non accommodative ( tonic) Refraction  Accomodative type Tonic type Age of onset > 2 years At birth Error of refraction Hypermetropia No error Angle of squint Usually small Large Binocular function Good Bad Amblyopia Rare Common Nystagmus Rare Common 1-Glasses: leads to: Surgery Treatment a-complete relief.or b-partial relief: = surgery. 2-surgery(curative). Convergent Accommodative Convergent Non accommodative NB Divergent squint Primary divergent squint is of good binocular function& treated surgically. 4-Primary or secondary (ocular pathology or amblyopia) Full ocular examination Lt. Leucocorea  Other classification of concomitant squint 1. Primary. 2. Secondary to obstacle in visual axis: a. Cataract. b. Central corneal scar. c. Macular scar. d. Retinoblastoma. 3. Consecutive: = Iatrogenic.  5-Angle of deviation Corneal reflection(Hirschberg test) Corneal reflection test (Hirschberg test) Corneal reflection test (Hirschberg test) 6-State of binocular single vision Worth's 4 dot test  Evaluation of a case of strabismus Examples of diagnosis A - Alternating conc. Convergent primary squint angle 25 acc. B – Right conc. Convergent primary squint angle 25 acc. C – Right conc. Convergent primary squint angle 25 non acc. D – Alter. conc. Convergent primary squint angle 25 non acc.  Management of a case of strabismus Purpose :  To improve visual acuity.  To improve binocular vision.  To improve cosmetic appearance.  Management of a case of strabismus 1-Optical : To improve visual acuity by : Glasses. Contact lens. Refractive surgery.  Management of a case of strabismus 2- Occlusion if there is amblyopia: (amblyopioa) To improve visual acuity by : Occlusion of sound eye. One week for every year. Bandage ,frosted glass , penalization.  Management of a case of strabismus 3- Orthoptics : To improve binocular single vision by : Synoptophore.  Management of a case of strabismus 4-Surgical : To improve alignment by : Weakening of a strong muscle. Strengthen of a weak muscle.  Amblyopia Amblyopia is impaired vision in the absence of organic disease. It is most likely the result of lack of continuous use of one fovea for vision. Types: 1. Strabismic amblyopia. 2. Anisometropic amblyopia. 3. Visual deprivation amblyopia (amblyopia ex anopsia). 4. Toxic amblyopia. 5. Nystagmic amblyopia. Treatment:  Treatment is based on forcing the patient to use the amblyopic eye for vision, after removing the cause.  Occlusion (patching) of the preferred eye ( sound ) is carried out. It is important to diagnose amblyopia as early as possible (before age 9 years)  Full time or part time occlusion Occlude the normal eye either continuous or intermittent.  Types of occluder Patch, atropine, semitransparent glass or by powerful convex lens. Duration For 1 week/ year old. Quizzes 1-Which of the following muscles depress the eye in adducted position? A)Superior rectus. B)Inferior rectus. C)Medial rectus. D)Superior oblique. E) Inferior oblique. 1-Which of the following muscles depress the eye in adducted position? A)Superior rectus. B)Inferior rectus. C)Medial rectus. D)Superior oblique. E)Inferior oblique. 2-Which of the following muscles elevates the eye in abducted position? A)Superior rectus. B)Inferior rectus. C)Medial rectus. D)Superior oblique. E)Inferior oblique. 2-Which of the following muscles elevates the eye in abducted position? A)Superior rectus. B)Inferior rectus. C)Medial rectus. D)Superior oblique. E)Inferior oblique. 3- Which of the following is a cause of binocular diplopia? A)Subluxation of the lens. B)Iridodialysis. C)Dislocation of the lens. D)Iridoscheisis. E)Symblepharon. 3- Which of the following is a cause of binocular diplopia? A)Subluxation of the lens. B)Iridodialysis. C)Dislocation of the lens. D)Iridoscheisis. E)Symblepharon. 4.Which of the following conditions is presented with abnormal head posture? A) Latent squint B) Paralytic squint C) Convergent concomitant squint D) Pseudo squint E) Divergent concomittant squint 4.Which of the following conditions is presented with abnormal head posture? A) Latent squint B) Paralytic squint C) Convergent concomitant squint D) Pseudo squint E) Divergent concomittant squint 5. A 3 year old child has convergent squint for one year. What is the first step of management ? A)Proper refraction B)Surgical correction C)Training on the synoptophore D)Prism prescription E)Examination with Hes screen 5. A 3 year old child has convergent squint for one year. What is the first step of management ? A)Proper refraction B)Surgical correction C)Training on the synoptophore D)Prism prescription E)Examination with Hes screen Case Scenario CASE 1  A four year old child is brought to clinic by his mother who has noticed a 'turn' in the right eye.  The strabismus is of recent onset and there is a family history. Aided visual acuity is 6/36 right, 6/6 left. The right eye slowly takes up fixation when the left eye is covered. The retina is easily seen and is normal. Refraction shows that both eyes are hypermetropic, the right more than the left. Q1: Describe the position of the right eye. Q2: What is the term used to describe the vision in the right eye? Can it be reversed in this patient? Q3: Give one indication of surgery in that child. CASE 2 A nine months-old child was referred from her pediatrician for crossed eyes. Birth history was normal. Physical health is good. Both right and left eye cross inwards. On Examination, there is normal fixation and following behavior. Child can alternate between right and left eye. Refraction reveals emmetropia. Cover test shows movement of each eye. No amblyopia is detected. A) What is your diagnosis? B) When to treat this condition? C) What is the main line of treatment of this condition ?