Objective The purpose of this study was to describe the clinical characteristics and natural history of convergence insufficiency (CI) in a population-based cohort of adults. Design Retrospectively reviewed population-based cohort. Participants Adult (age ≥19 years) residents of Olmsted County, Minnesota. Methods The medical records of all adults diagnosed with CI over a 20-year period were reviewed retrospectively. Main Outcome Measures Clinical characteristics and outcomes for adult-onset CI. Results A total of 118 adults (annual incidence, 8.44 per 100 000 patients older than 19 years) were diagnosed with CI during the 20-year period, constituting 15.7% of all forms of adult-onset strabismus observed in this population. The median age at diagnosis was 68.5 years (range, 21.7-97.1 years), and 68 (57.6%) were female. The mean initial exodeviation at near was 14.1 prism diopters (PD; range, 1-30 PD) and 1.7 PD (range, 0-10 PD) at distance. The Kaplan-Meier rate of exotropia increasing over time by 7 PD or more at near was 4.2% at 5 years, 13.5% at 10 years, and 24.4% at 20 years. Approximately 88% were managed with prisms, whereas less than 5% underwent surgical correction. Conclusions Adult-onset CI included approximately 1 in 6 adults who were newly diagnosed with strabismus in this 20-year cohort. There was a significant increase in incidence with increasing age. Nearly one-fourth had an increase of their near exodeviation of at least 7 PD by 20 years after their diagnosis, and most patients were managed conservatively.
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