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Kanski > Strabismus > Flashcards

Strabismus Flashcards

1
Q

Lateral rectus

A
  • originates at the annulus of Zinn
  • inserts 6.9 mm behind the temporal limbus
  • abduction
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2
Q

Superior rectus

A
  • originates at the annulus of Zinn
  • inserts 7.7 mm behind the superior limbus
  • forms an angle of 23 degrees with the visual axis
  • primary: elevation
  • secondary: adduction, intorsion
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3
Q

Medial rectus

A
  • originates at the annulus of Zinn
  • inserts 5.5 mm behind the nasal limbus
  • adduction
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4
Q

Inferior rectus

A
  • originates at the annulus of Zinn
  • inserts 6.5 mm behind the inferior limbus
  • forms an angle of 23 degrees with the visual axis
  • primary: depression
  • secondary: adduction, extorsion
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5
Q

Superior oblique

A
  • originates superiomedial to the optic foramen
  • passes forward through the trochlea
  • inserts in the posterior upper quadrant of th globe
  • forms an angle of 51 degrees with the visual axis
  • primary: intorsion
  • secondary: depression, abduction
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6
Q

Inferior oblique

A
  • originates from a small depression just behind the orbital rim lateral to the lacrimal sac
  • inserts in the posterior lower temporal quadrant of the globe close to the macula
  • forms an angle of 51 degrees with the visual axis
  • primary: extorsion
  • secondary: elevation, abduction
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7
Q

Ductions ; Versions ; Vergences

A

Ductions: monoocular movements

Versions: binocular, simultaneous, conjugate movements

Vergences: binocular, simultaneous, disconjugate movements

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8
Q

AC/A ratio

A

3-5 🔺

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9
Q

Synergists

Yoke muscles

A

Synergists: muscles of the same eye that moves the eye in the same direction
-R superior rectus & R inferior oblique (elevation)

Yoke muscles: contraleteral synergists
-L superior oblique & R inferior rectus

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10
Q

Sherrington law

A

increased innervation to an extraocular muscle is accomponied by a reciprocal decrease in innervation to its antagonist
-R medial rectus & R lateral rectus

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11
Q

Hering law

A

during any conjugate eye movement, equal and simultaneous innervation flows to the yoke muscles

 🔷in a paretic squint: secondary deviation > primary deviation
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12
Q

Horopter and Panum fusional space

A

Objects on the horopter: seen single and in one plane

Objects in Panum fusional areas: seen singly and stereoscopically

Objects outside Panum fusional areas: appear double

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13
Q

Normal values for fusional vergence

A

Convergence: 15-20🔺(distance), 25🔺(near)

Divergence: 6-10🔺(distance), 12-14🔺(near)

Vertical: 2-3🔺

Cyclovergence: 8*

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14
Q

Sensory adaptations to strabismus

A
  1. Supression: ➖ adaptation
    - central / peripheral
    - monoocular / alternating
    - facultative / obligatory
  2. Abnormal retinal correspondance (ARC): ➕ adaptation
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15
Q

Motor adaptations to strabismus

A

1- Face turn

2- Head tilt

3- Chin elevation/depression

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16
Q

Classification of amblyopia

A
  1. Strabismic ⚠️7-8 years
  2. Anisometropic ⚠️longer into the teens
  3. Stimulus deprivation
  4. Bilateral ametropic
  5. Meridional
17
Q

Hirschberg test

A

Border of the pupil: 15 degrees

Limbus: 45 degrees

18
Q

Cover test

Uncover test

A

Cover - TROPIA

Uncover - PHORİA

19
Q

When to prescribe👓

A 
Hypermetropia: >4⃣ D
     -0-1 yaş: >5⃣ D, 1-3 yaş: >4⃣ D
     -no squint: 2/3 correction
     -esotropia: full correction
Astigmatism: >1.5 D 
Myopia: 
     -5⃣ D
     -2-4 years: >3⃣ D
     ->4 years: even low 
     -0-1 yaş: >4⃣ D, 1-2 yaş: >3⃣ D, 2-3 yaş: >2⃣ D
20
Q

Early-onset esotropia

A
  • within the first 6 months
  • > 30🔺
  • surgery by the age of 12 months
  • inferior oblique overaction ➡️ V pattern
  • DVD (%80)
  • amblyopia in %50
21
Q

Accomodative esotropia

A
  1. Refractive: AC/A ↔️
    - presents at the age of 18 months to 3 years
    - fully / partially
  2. Non-refractive: AC/A ⬆️
    - convergence excess / hypoaccomodative convergence excess

Treatment: 8 years: manifest hypermetropia is prescribed

22
Q

Early-onset exotropia

A
  • presentation is often at birth
  • neurological anomalies are frequent ⚠️
  • treatment: surgery
23
Q

Duane retraction syndrome

A
  • failure of innervation of the hypoplastic 6⃣th nerve and anomalous innervation from the 3⃣rd nerve instead, to the lateral rectus
  • associated systemic defects⚠️: deafness, external ear abnormalities, speech disorder, skeletal abnormalities
  • face turn
  • restriction of abduction
  • retraction of the globe on adduction
  • majority do not need surgery
24
Q

Möbius syndrome

A
  • congenital non-progressive bilateral 6⃣th and 7⃣th cranial nerve palsies
  • bilateral facial palsy
  • limb anomalies, mild mental handicap may be present
25
Q

Brown syndrome

A
  • mechanical restriction of the superior oblique tendon
  • usually congenital
  • limited elevation in add, normal elevation in abd
  • congenital cases do not usually require treatment as long as binocular function is maintained with an acceptable head posture
26
Q

Zinn halkasından geçen yapılar

A
  • NC 2 (a. v. centralis retina)
  • a.ophthalmica
  • NC 3
  • NC 6
  • n.nasociliaris
27
Q

XT-ameliyat endikasyonları

A

✳️ambliyopi gelişiyor, konverjans azalıyor, kayma miktarı artıyorsa cerrahi yapılmalı
✳️mümkün olan en kısa zamanda ameliyat yapılmalı(binoküler tek görme için)

İntermittant XT:
Diverjans fazlalılığı➡️her iki LR geriletme
Yalancı diverjans fazlalığı➡️LR geriletme MR rezeksiyon
Konverjans zayıflığı➡️her iki MR rezeksiyon

Devamlı XT➡️LR geriletme MR rezeksiyon
Sekonder XT➡️LR geriletme MR rezeksiyon

28
Q

Anormal baş pozisyonu

A

Vertikal kas patolojisi-gözlerden herhangi birisinin kapatılması

Oblik kas patolojisi-patolojinin bulunduğu gözün kapatılması

baş pozisyonunun düzeltilmesini sağlar

29
Q

Yalancı şaşılık ve Kappa açısı

A

➖ kappa-yalancı EZOtropi

➕kappa-yalancı EKZOtropi

30
Q

Gözlükte prizmatik etki

A

> 4️⃣D

Hipermetrop-kayma olduğundan daha AZ ölçülür

Miyop-kayma olduğundan daha FAZLA ölçülür

31
Q

Hirschberg-Kayma

A

Kornea MERKEZİ-1mm=7-8derece

Kornea PERİFERİ-1mm=5-6derece

32
Q

Kappa açısı

A

Işık reflesi,

nazalde-➕kappa

temporalde-➖ kappa

➕5️⃣ kappa-FİZYOLOJİK

Kanski (7 decks)

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