Prevalence of Strabismus in Individuals Aged 13 and Above in the US and Globally
The prevalence of strabismus in individuals aged 13 and above is approximately 2.5-4% in the adult population globally, with esotropia being twice as common as exotropia in adults. 1, 2
Global Prevalence Data
Adult Population (≥13 years)
Strabismus Subtypes in Adults
- Esotropia vs. Exotropia: Esotropia is approximately twice as common as exotropia in adults 2
- Specific prevalence rates:
Risk Factors and Associations
Ocular Risk Factors
- Refractive errors significantly increase strabismus risk 2:
- Anisometropia >1.0 diopters: 3.61 times higher risk
- Anisometropia >2.0 diopters: 6.93 times higher risk
- Astigmatism ≥1.0 diopters: 2.09 times higher risk
- Astigmatism ≥2.0 diopters: 3.74 times higher risk
- Hyperopia: Each diopter increase associated with 1.43 times higher risk
- Visual acuity: Low visual acuity in the worse seeing eye (≥1.3 logMAR) has a strong association with strabismus (OR 21.7) 2
Demographic Factors
- Age: Heterogeneity in prevalence across age groups, with WHO region and publication year affecting prevalence estimates 5
- Regional variations: Significant differences in prevalence exist across WHO regions 5
Impact on Quality of Life
Strabismus significantly impacts quality of life in adults:
- Vision-related quality of life is measurably lower in individuals with strabismus compared to those without strabismus (B = -5.96, P < 0.001) 2
- Psychosocial impact: Adults with strabismus without diplopia tend to have primarily psychosocial concerns 4
- Functional impact: Adults with strabismus and diplopia tend to have more concerns relating to functional quality of life 4
Common Causes of Adult Strabismus
The most common causes of strabismus in adults include:
- Unresolved or recurrent childhood strabismus
- Sensory strabismus
- Divergence insufficiency or sagging eye syndrome
- Graves orbitopathy
- 4th and 6th cranial nerve palsies
- Convergence insufficiency 1
Clinical Considerations
- Surgical outcomes: Successful motor alignment can be achieved in approximately 85% of adult patients after one surgical procedure 3
- Sensory outcomes: Sensory success varies significantly between patients with strabismus onset after visual maturation (81%) versus before visual maturation (25%) 3
- Subjective success: Despite differences in motor and sensory outcomes, subjective success rates are high (94%) in both early and late-onset strabismus patients 3
Caveats and Limitations
- Definitions of strabismus vary across studies, making direct comparisons challenging 1
- Most prevalence studies focus on either children or specific adult age ranges, with limited data specifically on adolescents (13-18 years)
- Heterogeneity in measurement techniques and definitions contributes to variations in reported prevalence rates 5
- The prevalence data presented represents manifest strabismus and may not include intermittent forms that could be missed in population screening
Understanding the prevalence and impact of strabismus in adolescents and adults is essential for appropriate resource allocation and development of targeted interventions to address both the functional and psychosocial aspects of this condition.