Incidence, types, and lifetime risk of adult-onset strabismus

Objective: To describe the incidence and types of adult-onset strabismus in a geographically defined population.

Design: Retrospectively reviewed population-based cohort.

Participants: All adult (≥19 years of age) residents of Olmsted County, Minnesota, diagnosed with new-onset adult strabismus from January 1, 1985, through December 31, 2004.

Methods: The medical records of all potential cases identified by the resources of the Rochester Epidemiology Project were reviewed.

Main outcome measures: Incidence rates for adult-onset strabismus and its types.

Results: Seven hundred fifty-three cases of new-onset adult strabismus were identified during the 20-year period, yielding an annual age- and gender-adjusted incidence rate of 54.1 cases (95% confidence interval, 50.2-58.0) per 100 000 individuals 19 years of age and older. The 4 most common types of new-onset strabismus were paralytic (44.2% of cases), convergence insufficiency (15.7%), small-angle hypertropia (13.3%), and divergence insufficiency (10.6%). The incidence of adult-onset strabismus overall and its 4 most common forms significantly increased with age (P <0.001 for all), with a peak incidence in the eighth decade of life. The lifetime risk of being diagnosed with adult-onset strabismus was 4.0% in women and 3.9% in men.

Conclusions: Paralytic strabismus was the most common subtype of new-onset adult strabismus in this population-based cohort. All of the most common forms of adult-onset strabismus increased with age, especially after the sixth decade of life. Further characterization of strabismus types found in this study is warranted to better define this disorder.