Classification:

1. Nonparetic (Comitant)
1. Non-accomodative
1. Infantile
2. Acquired
2. Accomodative
1. Hyperopic
2. High AC/A ratio
3. Partially accommodative
2. Paretic (Non Comitant)
3. Pseudoesotropia

Paretic: due to paresis or paralysis of one or more EOM.

Comitant: the deviation is approximately the same in all gazes.

Comitant = Nonparetic ; usually more common in children

Non comitant = Paretic; usually more common in adults.

- Most common type of esotropia

• Usually occurs before the age of 6 months,
• Comitant
• Etiology: ? faulty innervational control involving the supranuclear pathways for convergence and divergence and their neural connections to the medial longitudinal fasciculus.
• Hereditary: Autosomal Dominant
• Deviation is often large (>40 prism diopters)
• Most common error of refraction is hyperopia.
• Frequently associated with nystagmus, overaction of the inferior obliques and DVD.
• Alternate fixation: occurs if at various times either eye is used for fixation à  vision will be nearly equal in both eyes.
• Cross fixation: occurs with large angle esotropia when the right eye is used for left gaze and the left eye is used for right gaze.

• Correction of hyperopia
• Treatment of amblyopia
• Surgical treatment: Bimedial rectus recessions or medial rectus recession and lateral rectus resection.

• Usually occurs after the age of 2 years.
• Angle of deviation is smaller than in infantile ET but may increase with time.

• There is a normal mechanism of accommodation with associated overaction of the convergence response and insufficient relative fusional divergence to maintain the eyes straight.
• 2 types:

High Hyperopia: requiring high accommodation and therefore

convergence. Treatment: full cycloplegic correction.

High AC/A ratio: (Accomodative convergence to

accomodation). The deviation is greater at near than at

distance.

Treatment is full cycloplegic correction +/- bifocals.

 

• More common in adults
• Differential Diagnosis:

1. Microvascular diseases: Diabetes and Hypertension
2. Inflammatory and infectious CNS disorders: meningitis, raised ICP
3. CNS tumors
4. Head trauma

• ET is greater at distance than at near.
• Treatment: Wait till 6-8 weeks: Botulinum toxin.
• > 6 months: medial rectus recession + lateral rectus resection.

• Occurs in patients with flat broad nasal bridge and prominent epicanthal folds.
• Gradually disappears with age.
• Hirschberg test differentiates it from true esotropia.

• Less common than esotropia but incidence increases with age.
• May progress from exophoria to intermittent exotropia to constant exotropia.
• Possibly hereditary: Autosomal Dominant.
• Types:

1. Basic Exotropia: D=N
2. Divergence Excess D>N
3. Convergence Insufficiency N>D

• Most common type.
• Onset of deviation within the first year of age
• Characteristic sign is closing one eye in bright light
• Not associated with any specific error of refraction.
• Usually not associated with amblyopia.
• Treatment:

1. Correction of refractive error
2. Treatment of amblyopia if present
3. Surgical treatment for deteriorating intermittent XT:
   a. Bilateral lateral rectus recession (if D>N)
   b. Resection of medial and recession of lateral rectus (if N>D)

    

• May be present at birth or may progress from intermittent XT.
• Sensory XT: one form of constant XT that occurs following loss of vision in one eye (ex. After trauma)
• Associated with suppression in young age to avoid diplopia.
• Treatment: Surgical correction.

• A horizontal deviation may be different in upgaze versus downgaze, forming A and V patterns.
• A pattern shows more esotropia (or less exo) in upgaze
• V pattern shows more exotropia (or less eso) in downgaze.
• A pattern is significant if greater than 10 prism diopters.
• V pattern is significant if greater than 15 prism diopters.
• They are frequently associated with overaction of the oblique muscles:

a. Inferior oblique for V pattern
b. Superior oblique for A pattern.

• Usually occur after childhood.
• Deviation named according to the nonfixing or "bad" eye.
• Can be produced by systemic disorders ex. Orbital tumors, brainstem lesions, myasthenia gravis, multiple sclerosis and Grave’s disease.
• Most common symptom is diplopia (if deviation occurs after age 6). Suppression occurs if age is less than 6 years.
• Most are noncomitant.
• The most commonly paretic vertical muscle is the superior oblique
• The first muscle to be involved in Grave’s disease is the inferior rectus.
• Maximal deviation occurs in the field of action of the paretic muscle.

Characterized by :

• Marked limitation of abduction
• Mild limitation of adduction
• Retraction of the globe and narrowing of the palpebral fissure on adduction
• Upshoot or downshoot on adduction.

• Incidence: It is more common in the left eye.
• Pathology: Faulty innervation of the lateral rectus by fibers from the medial rectus à does not obey Sherrington’s law. This results in cocontraction of the medial and lateral rectus muscles.
• May cause compensatory face turn to the Duane’s eye side.