Download Strabismus

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