Mohamad Abdelzaher MSc 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

center of rotation 12-13 mm behind cornea 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 - compesated vs decompensated 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

1) correct refractive error 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 Congenital Traumatic Inflammatory Vascular Neoplastic Metabolic Toxic

Symptoms: Diplopia Ocular deviation Abnormal head posture

Signs: Ocular deviation: “Hering law” “Angle of deviation”

2) Limitation of movement 3) Binocular diplopia - homonymous “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

Pupil 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 “angle of deviation” Types: - 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 Accommodative Essential: 6 mo, >15ᵒ, ref +2D, DVD,IO overaction Cross fixation Sensory (Amblyopia) Convergence excess Divergence insuffeciency Basic Microtropia Acute Refractive (normal AC/A ratio) - Full - Partial Non-refractive (abnormal AC/A ratio) 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

Alternate Cover test with Prism Exotropia, Constant Prism cover test 20 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: Lines: Restore binocular vision Improve VA Restore normal appearance Lines: Cycloplegic refraction & error correction Treat amblyopia: occlusion – penalization Treat eccentric fixation (Pleoptics) Orthoptics Surgery

Nystagmus Definition Types Pendular Jerky Vestibular Central Ocular Physiological Pathological

Clinical Approach to squint

History Age of onset: - Documentation - Significance Direction of deviation: Eso, Exo, Hyper, Hypo Which eye: Alternate? Always the same eye? Mode of onset: sudden? Gradual? Ppt factors Type of deviation: Constant? Intermittent? Family photos Essential ET (6mo) – Accommodative ET (3yrs) Amblyopia H/O trauma, fever, neurologic disorder Intermittent  fusion present  good prognosis

6) Prior treatment: Glasses. Occlusion. Prisms. E. D. Surgery 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 Lid fissure: Ptosis III nerve palsy - mysthenia

Exophthalmos - Enophthalmos Graves’ blow out fracture

Hypertelorism - Epicanthal folds Pseudo Exotropia Pseudo Esotropia

2) Head posture Face turn Head tilt Chin up/down Right VI palsy

3) Fixation preference: Unilateral Alternating Amblyopia

Alternate Cover test Exotropia, Constant

4) Constancy of deviation: Constant Variable - Incomitant - Uncorrected refractive error Hering law

5) Nystagmus Essential ET Oscillopsia

III nerve palsy - mysthenia Graves’ – blow out fracture III nerve palsy Pseudo strabismus Amblyopia - Incomitant - Uncorrected ref error

Assessment of vision in non verbal children Visual Acuity Assessment of vision in non verbal children Fixation and following Preferential looking Catford drum VEP

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

Alternate Cover test with Prism Exotropia, Constant Prism cover test 20 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 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