Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Strabismus Mohamad Abdelzaher MSc The reason why so few good books are written is that so few people who can write know anything. Walter Bagehot Anatomy of EOMs • 4 recti • 2 obliques • Origin • Annulus of Zinn • Course of EOMs • Insertion of recti: Spiral of Tilluax • Insertion of obliques • Nerve Supply: III nerve: all except, L6 SO4 • Rotation of the eye: center of rotation 12-13 mm behind cornea Adduction (Z) Abduction (Z) Elevation (X) Depression (X) Intorsion (Y) Extorsion (Y) • Action of EOMs • Orbital vs Visual axes * Action of right SR • Action of right SO • Regarding the torsion movement: “There is only on (I) in the sentence” SO -------- Intorsion IO --------- Extorsion SR -------- Intorsion IR --------- Extorsion • Action of EOMs • Binocular movement • Diagnostic positions of gaze Binocular Vision Pseudo Strabismus • • • • Pseudo eso Pseudo exo Pseudo hyper Pseudo hypo CORNEAL LIGHT REFLEX • Epicanthus • Ptosis Heterophoria • • • • Definition “binocular vision” Types Aetiology Clinical picture - compesated vs decompensated -- how to dissociate binocular vision: 1) cover test 2) Maddox rod 3) Maddox wing Cover test Cover – Uncover test Orthophoria, normal No complaints, asymptomatic Cover – Uncover test Esophoria, abnormal, common Only seen when eye is covered Often asymptomatic, no complaints Note OS does not move. Cover – Uncover test Exophoria, abnormal, common Only seen when eye is covered Note OS does not move Often asymptomatic, no complaints. • Maddox rod • Maddox wing • Treatment: - Indications - Lines: 1) correct refractive error 2) orthoptic exercise: pencil-nose exercise exercising prism synoptophore 3) Relieving prisms 4) Surgery • Exercising prisms e.g. base-out prism to exercise exophoria • synoptophore Paralytic squint • Definition “angle of deviation” • Aetiology: LMNL - nuclear - nerve - muscle 1) 2) 3) 4) 5) 6) 7) Congenital Traumatic Inflammatory Vascular Neoplastic Metabolic Toxic • Symptoms: - Diplopia - Ocular deviation - Abnormal head posture • Signs: 1) Ocular deviation: “Hering law” “Angle of deviation” 2) Limitation of movement “9 diagnostic positions of gaze” 3) Binocular diplopia - homonymous - heteronymous 4) Diplopia chart • Complications: Direct antagonist ------------- contracture Indirect synergist ------------- contracture Contralateral antagonist --- underaction False projection (Hess screen) OD LR Palsy Clinical features of nerve palsies • 6th nerve palsy: - Ocular deviation Binocular diplopia Limitation of ocular movement Abnormal head posture • 4th nerve palsy: - Ocular deviation Binocular diplopia Limitation of ocular movement Abnormal head posture • 3rd nerve palsy: - Ocular deviation Binocular diplopia Limitation of ocular movement Abnormal head posture Pupil • Treatment: - Treat the cause - Temporary treatment: occlusion, prisms Surgical treatment: weakening ----------------> recession strengthening -----------> resection Questions 1. You have a patient with diplopia. His left eye is turned down and out and his lid is ptotic on that side. What nerve do you suspect and what should you check next? • This sounds like a CN3 palsy, and you should check his pupillary reflex. Pupillary involvement means the lesion is from a compressive source such as an aneurysm. 2. This 32 year old overweight woman complains of several months of headaches, nausea, and now double vision. What cranial nerve lesion do you see in this drawing. What other findings might you expect on fundus exam and what other tests might you get? • This looks like an abducens palsy … actually a bilateral 6th nerve palsy as the patient can’t get either eye to move laterally. While the majority of abducens palsies occur secondary to ischemic events from diabetes, this seems unlikely in a young patient. Her symptoms sound suspicious for pseudotumor (obese, headaches). You should like for papilledema of the optic nerve, get imaging, and possibly send her to neurology for a lumbar puncture with opening pressure. 3. A patient is sent to your neurology clinic with a complaint of double vision. Other than trace cataract changes, the exam seems remarkable normal with good extraocular muscle movement. On covering the left eye with your hand, the doubling remains in the right eye. What do you think is causing this case of diplopia? • The first question you must answer with a case of diplopia is whether it’s monocular or binocular. This patient has a monocular diplopia. After grumbing to yourself about this patient being inappropriately referred to your neurologic clinic, you should look for refractive problems in the tear film, cornea, lens, etc.. 12. A young man complains of complete vision loss (no light perception) in one eye, however, he has no pupil defect. Is this possible? How might you check whether this patient is “faking it?” • Assuming the rest of the eye exam is normal (i.e. the eye isn’t filled with blood or other media opacity) this patient should have an afferent pupil defect if he can’t see light. There are many tests to check for malingering: you can try eliciting a reflexive blink by moving your fingers near the eye. One of my favorite techniques is to hold a mirror in front of the eye. A seeing eye will fixate on an object in the mirror. Gentle movement of the mirror will result in a synchronous ocular movement as the eye unconsciously tracks the object in the mirror. Concomitant squint • Definition • Types: “angle of deviation” - Acc to direction of deviation: esotropia exotropia hypertropia hypotropia - Acc to laterality of deviation: unilateral alternating • Clinical picture - ocular deviation - defective vision - diplopia??? Concomitant Esotropias Non Accommodative 1) Essential: 6 mo, >15ᵒ, ref 2) 3) 4) 5) 6) 7) +2D, DVD,IO overaction Cross fixation Sensory (Amblyopia) Convergence excess Divergence insuffeciency Basic Microtropia Acute Accommodative Refractive (normal AC/A ratio) - Full - Partial Non-refractive (abnormal AC/A ratio) -Convergence excess -Accommodation weakness • IO overaction • DVD AC/A Ratio Refractive Accommodative Esotropia Refractive Partially Accommodative Esotropia Convergence excess esotropia Concomitant Exotropias • Early onset: at birth, normal refraction, large angle, associated neurological manifestations, surgical ttt • Intermittent: around 2 years, decompesated exophoria • Sensory: older children & adults • Consecutive: following surgical correction of ET Management of strabismus • • • • • History: age of onset, duration, glasses Exam ocular media: cornea, lens, … Fundus exam & refraction (cycloplegic) VA: Amblyopia Motility in 9 directions of gaze Cover test Alternate Cover test Exotropia, intermittent May be visible with or without alternate cover May have intermittent diplopia, especially when tired or sick Mom sees misalignment every now and then. Alternate Cover test Exotropia, Constant May be visible with or without alternate cover May or may not have constant diplopia • Measurement of angle of deviation: - Corneal reflex: pupillary magin -----15ᵒ midway ----------------30ᵒ limbus -----------------45ᵒ - Prism: 1ᵒ = 2 ∆ - Synoptophore Prism cover test Alternate Cover test with Prism Exotropia, Constant Use prism to quantitate the deviation. Change prism power until movement is neutralized. • Worth 4 dot test (Binocular vision) Treatment • Aims: 1) Restore binocular vision 2) Improve VA 3) Restore normal appearance • Lines: 1) 2) 3) 4) 5) Cycloplegic refraction & error correction Treat amblyopia: occlusion – penalization Treat eccentric fixation (Pleoptics) Orthoptics Surgery Nystagmus • Definition Pendular Jerky • Types Vestibular Central Ocular Physiological Pathological Clinical Approach to squint History 1) Age of onset: - Documentation Family photos - Significance Essential ET (6mo) – Accommodative ET (3yrs) 2) Direction of deviation: Eso, Exo, Hyper, Hypo 3) Which eye: Alternate? Always the Amblyopia same eye? 4) Mode of onset: sudden? Gradual? Ppt factors H/O trauma, fever, neurologic disorder 5) Type of deviation: Constant? Intermittent? Intermittent fusion present good prognosis 6) Prior treatment: Glasses? Occlusion? Prisms? E.D? Surgery? 7) Medical History: Birth weight, Incubation, Neurological ROP Mysthenia Clinical Approach to squint Family photos Amblyopia H/O trauma, fever, neurologic disorder Intermittent fusion present good prognosis Intermittent exotropia, corneal or conj disease ROP Mysthenia Inspection of the patient 1) Lid fissure: - Ptosis III nerve palsy - mysthenia - Exophthalmos Graves’ - Enophthalmos blow out fracture - Hypertelorism Pseudo Exotropia - Epicanthal folds Pseudo Esotropia 2) Head posture Face turn Right VI palsy Head tilt Chin up/down 3) Fixation preference: Alternating Unilateral Amblyopia Alternate Cover test Exotropia, Constant 4) Constancy of deviation: Constant Variable - Incomitant Hering law - Uncorrected refractive error 5) Nystagmus Essential ET Oscillopsia III nerve palsy - mysthenia Graves’ – blow out fracture III nerve palsy Pseudo strabismus Amblyopia - Incomitant - Uncorrected ref error Visual Acuity Assessment of vision in non verbal children Fixation and following Preferential looking VEP Catford drum Stereopsis Binocular Vision Titmus Fly test Ductions & Versions • Duction movement • Binocular movement • Diagnostic positions of gaze Cover test Cover – Uncover test Orthophoria, normal No complaints, asymptomatic Cover – Uncover test Esophoria, abnormal, common Only seen when eye is covered Often asymptomatic, no complaints Note OS does not move. Cover – Uncover test Exophoria, abnormal, common Only seen when eye is covered Note OS does not move Often asymptomatic, no complaints. Cover test Alternate Cover test Exotropia, intermittent May be visible with or without alternate cover May have intermittent diplopia, especially when tired or sick Mom sees misalignment every now and then. Alternate Cover test Exotropia, Constant May be visible with or without alternate cover May or may not have constant diplopia Prism cover test Alternate Cover test with Prism Exotropia, Constant Use prism to quantitate the deviation. Change prism power until movement is neutralized. Questions • A mother brings in her 5-month-old boy because his eyes have been tearing for a couple of months. On further questioning, she reports no discharge or redness, but he squints and turns away from bright lights. He has no significant past ocular or medical history. 1 What is the differential diagnosis? 2 What exam findings would you look for? • You are asked to see a 3-year-old girl with an eye turn. Apparently the child's eyes have turned inward since she was a baby, but now the mother notices that the left eye also goes up. 1 What is the differential diagnosis? 2 What exam findings would enable you to determine the correct diagnosis? Additional information: her best-corrected visual acuity is 6/6 OU with +1.00 D OD and +1.50 D OS. The AC/A ratio is normal. The ET is comitant and measures 35 prism diopters at distance and near. She does cross fixate, and there is inferior oblique overaction. There is also no dissociated vertical deviation (DVD) or latent nystagmus present. Worth 4 dot testing demonstrates suppression OS 3 What type of esotropia does this girl have? Thank you