## Classification and Epidemiology of Non-Paralytic Strabismus ### Types of Non-Paralytic Strabismus | Type | Characteristics | Prevalence | | --- | --- | --- | | **Esotropia** | Inward deviation of eye(s); convergent squint | Most common (60–70% of concomitant strabismus) | | **Exotropia** | Outward deviation of eye(s); divergent squint | Second most common (20–30%) | | **Hypertropia** | Upward deviation of one eye | Least common (5–10%) | | **Cyclotropia** | Rotational deviation | Rare, usually associated with paralytic strabismus | **Key Point:** Esotropia is the most common type of concomitant strabismus in children, accounting for approximately 60–70% of all cases of non-paralytic squint. ### Subtypes of Esotropia **Mnemonic: AAAC** — Accommodative, Acute, Acquired, Consecutive 1. **Accommodative esotropia** — Most common subtype; related to hyperopia and accommodation-convergence relationship 2. **Non-accommodative esotropia** — Due to excessive convergence or weak divergence 3. **Partially accommodative** — Responds partially to glasses 4. **Infantile esotropia** — Presents within first 6 months of life **High-Yield:** Accommodative esotropia responds well to hyperopic correction (convex lenses), whereas non-accommodative esotropia requires surgical intervention. ### Clinical Pearl The high prevalence of esotropia in children is attributed to: - High prevalence of hyperopia in the pediatric population - Immature vergence control mechanisms - Increased accommodation-convergence relationship in young children [cite:Parson's Diseases of the Eye 21e Ch 12] 
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