Esotropia

Esotropia Basics - Eyes Inward Bound

• Esotropia: Inward turning of one or both eyes; a manifest deviation (tropia).
• Key Classifications:
  • Comitancy:
    • Comitant: Deviation angle constant in all gazes.
    • Incomitant: Angle varies with gaze direction.
  • Age of Onset:
    • Infantile: Birth to 6 months.
    • Acquired: After 6 months.
  • Laterality: Unilateral or Alternating.
  • Fixation Pattern (Frequency): Constant or Intermittent.

⭐ Esotropia is the most common type of strabismus in childhood; infantile esotropia typically presents before 6 months of age and is often associated with cross-fixation.

Infantile Esotropia - Early Eye Turn

• Onset: First 6 months life, healthy infant.
• Angle: Large (> 30 PD), constant, comitant.
• Refraction: Mild hyperopia (normal for age).
• Amblyopia: High risk; prompt management crucial.
• Associations:
  • Cross-fixation (common).
  • Dissociated Vertical Deviation (DVD).
  • Inferior Oblique Overaction (IOOA).
  • Latent Nystagmus.
• Treatment:
  • Surgical: Bilateral Medial Rectus (BMR) recession.
  • Timing: 6-18 months for binocular potential.
  • Manage amblyopia, significant refractive errors.

⭐ Cross-fixation is very common; infant uses adducted eye for contralateral gaze, may mimic bilateral CN VI palsy.

Accommodative Esotropia - Focusing Foibles

Esotropia (ET) from excessive accommodation. Caused by uncorrected hypermetropia (refractive) or high AC/A ratio (non-refractive). Onset: 6 months - 7 years (peak 2-3 years).

• Types & Characteristics:
  • Refractive: Hypermetropia > +2.0 D. Normal AC/A. ET often intermittent.
  • Non-refractive: High AC/A ratio. ET greater at near. Minimal hypermetropia.
  • Partially accommodative: ET reduces, not eliminated, with full hypermetropic correction.
• Treatment:
  • Full cycloplegic hypermetropic correction (glasses).
  • Bifocals for high AC/A.
  • Surgery for residual non-accommodative ET.

⭐ > Full cycloplegic refraction is crucial for diagnosis and initial management.

Diverse Esotropias - Unique Eye Turns

Esotropia Workup - Uncrossing Wires

• History: Onset (<6mo congenital, >6mo acquired), constant/intermittent, family Hx.
• Visual Acuity (VA): Age-appropriate; assess amblyopia, fixation.
• Alignment & Measurement:
  • Cover-Uncover (tropia), Alternate Cover + Prisms (deviation).
  • Hirschberg/Krimsky for objective angle.
• Cycloplegic Refraction: CRITICAL (Atropine/Cyclopentolate) for full hypermetropia.
• Motility: Ductions, versions; check restrictions/overactions (e.g., IOOA).
• Fundoscopy: Dilated exam; rule out organic causes (retinoblastoma), pseudoesotropia.
• Sensory Tests: Stereoacuity, Worth 4 Dot Test (suppression, fusion).

⭐ Cycloplegic refraction is crucial to identify hypermetropia, key for accommodative esotropia diagnosis.

High‑Yield Points - ⚡ Biggest Takeaways

• Infantile esotropia: Onset < 6 months, large angle, often with DVD & IOOA. Surgery is key.
• Accommodative esotropia: Most common, linked to hypermetropia & high AC/A ratio. Glasses primary treatment.
• Pseudoesotropia: Apparent inward turn, normal corneal reflex; due to epicanthal folds.
• Amblyopia is a major risk in childhood esotropia; early detection crucial.
• Sixth nerve palsy: Acquired esotropia, limited abduction, diplopia.
• Duane Syndrome Type 1: Esotropia, limited abduction, globe retraction on adduction.