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Accommodative Esotropia

• Onset usually between the 6th month and 7th year (most commonly around the 3rd year)

Refractive accommodative esotropia

• Normal AC/A ratio; esotropia is a physiological response to excessive hyperopia (usually between +2 and +7dpt)
• Full accommodative esotropia: Esotropia disappears after optical correction of hyperopia
• Partial accommodative esotropia: Partial reduction of esotropia after correction of hyperopia

Non-refractive accommodative esotropia

• With convergence excess: High AC/A ratio due to increased accommodative convergence (accommodation is normal, but convergence is increased). Normal near point of accommodation, esotropia at near with suppression, parallel eye position with binocular single vision at far distance, parallel eye position achieved with bifocal glasses
• With accommodative weakness = hypoaccommodative convergence excess: High AC/C ratio due to decreased accommodation (weak accommodation, leading to increased effort resulting in strong convergence). Distant near point of accommodation, esotropia at near with suppression, parallel eye position with binocular single vision at far distance.
• Treatments: Correction of refractive error, bifocal glasses, surgery

 

Non-accommodative Esotropia

Infantile Esotropia

• Disease
  • Family history of strabismus is common
  • Increased incidence in cerebral palsy and hydrocephalus
  • Esotropia is abnormal after the 4th month
  • Develops within the first 6 months in an otherwise healthy child (without significant refractive error and without restrictions in eye movement), slight hyperopia possible
  • Squint angle is usually large (>30 prism diopters) and stable.
  • Crossfixation, alternating fixation typically in the primary position
• Associated with:
  • Latent nystagmus: Fast phase toward the fixing eye when one eye is covered, (nystagmus occurs in both eyes). Binocular vision is better than monocular vision! Manifest latent nystagmus occurs when nystagmus appears in both eyes with both eyes open
    • Differential diagnosis: Nystagmus blockage syndrome – Over-accommodation resulting in esotropia to dampen nystagmus, as the null point of latent nystagmus lies in adduction
  • Inferior oblique overaction (= Strabismus Sursoadductorius) in about 70% of cases, usually from the 2nd year
  • Dissociated vertical deviation (DVD) develops in 80% of cases by the age of 3.
  • Asymmetry of monocular optokinetic nystagmus
• Findings
  • Normal head impulse test -> abduction possible -> rule out abducens nerve palsy!
  • No synkinetic lid movements during lateral gaze -> rule out Duane syndrome
  • No relevant refractive errors -> exclusion of accommodative component, correct minor hyperopia if present
• Treatment
  • Any amblyopia therapy before surgery
  • Surgery in Switzerland usually recommended only in preschool/school age (since the potential for binocular fusion or function is limited)

Microstrabismus

• Very small strabismus angle of manifest strabismus of 8 prism diopters or less
• Primary or secondary after surgery for large-angle strabismus
• Often associated with other findings, such as amblyopia in anisometropia
• Central suppression scotoma in the squinting eye
• Anomalous retinal correspondence with reduced stereopsis
• Symptoms are rare if no decompensated heterophoria is present
• Treatment: correction of refractive errors and occlusion for amblyopia treatment

Esotropia at near

• = Non-accommodative convergence excess/convergence spasm
• Mostly older children and young adults without significant refractive errors
• Orthotropia or small esophoria with divergence excess at distance
• Esotropia at near but normal or low AC/A ratio
• Normal near point of accommodation
• Treatment: bilateral medial rectus recessions

Esotropia at distance

• Divergence insufficiency
  • Healthy, often myopic, young adults
  • Intermittent or constant esotropia at distance with minimal or no esotropia at near (esotropia at distance at least 10 prism diopters more than at near)
  • Normal bilateral abduction
  • Fusional divergence amplitudes may be reduced
  • No neurological disease
  • Treatment: prisms until spontaneous resolution or surgery in persistent cases
• Divergence paralysis
  • Rare condition with a neurological comorbidity (e.g., intracranial mass, stroke, head trauma)
  • Primarily a concomitant esodeviation with reduced or absent divergence fusion amplitudes (difficult to distinguish from abducens nerve palsy)
  • Therapy: prisms

Decompensated Esophoria

• Breakdown of fusional divergence
• Often occurs after illness, emotional stress, trauma

Late-onset normosensorial Esotropia

• Onset after completion of binocular vision development, after the age of 3
• Findings: sudden onset with diplopia and esotropia, normal eye movements, typically squinting of one eye
• Usually no significant refractive error, no pronounced amblyopia at initial presentation
• Cave: rule out abducens nerve palsy!
• Treatment
  • refractive correction
  • if amblyopia exists: occlusion therapy
  • prism correction or surgery preferably within six months to prevent loss of binocular vision

Sensory Esotropia

• Due to unilateral reduction in visual acuity

Consecutive Esotropia

• After surgical overcorrection of exodeviation

Cyclic Esotropia

• Alternating between manifest esotropia with suppression and binocular single vision, both lasting for 24 hours and can persist for months or years

Esotropia in high myopia

• Associated with instability of the muscle pulleys

Spasm of the near reflex

• Functional disorder, mainly affects women, can occur at any age
• Findings: diplopia, blurred vision, and headaches associated with esotropia, pseudomyopia, and miosis (key to diagnosis!)
• Treatment: try to avoid triggering activities, consider atropine, provide full near correction

Differential diagnoses

• Abducens nerve palsy
• Duane retraction syndrome type I
• Möbius syndrome
• Restrictive muscle diseases

Sources

• EyeWiki Esotropia
• The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease; Nika Bagheri MD, Brynn Wajda MD, et al; Lippincott Williams&Wilkins; 7th Edition (2016)
• Kanski’s Clinical Ophthalmology: A Systematic Approach; Jack J. Kanski MD, Brad Bowling MD; Saunders Ltd.; 8th Edition (2015)