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  • Prevalence and clinical features of adult-onset nonparalytic, small-angle hypertropia

    Pediatric Ophth/Strabismus

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    This study describes the prevalence and clinical features of a common but underrecognized disorder of adult vertical strabismus.

    Study design

    The authors performed a retrospective review of adult patients diagnosed with a nonparalytic, small-angle hypertropia (NPSAH) over a 20-year period (1985-2004) in Olmsted County, Minnesota.

    Outcomes

    A diagnosis of NPSAH was given to 99 (13.1%) of 753 adults with strabismus, with an annual incidence of 7.5 per 100,000 adult residents and a cumulative incidence of 1.28%. The median age at diagnosis was 71 years (range, 27-98) and 64% of patients diagnosed with NPSAH were women. Most patients were diplopic, with angle of deviation progressing slowly over time. The mean deviation of 2 prism diopters increased to 4 prism diopters after a median follow-up of 10.8 years. About 85% of patients received prisms in spectacles.

    Limitations

    Given the initial median angle of hypertropia (only 2 prism diopters at both near and far distances), the prevalence is likely underestimated in the study population. Considering the racial and ethnic composition of Olmsted County, the results of this study are best extrapolated to the small, urban, white populations of the United States.

    Clinical significance

    As NPSAH is relatively common among elderly adults, earlier identification and treatment of these patients would improve patient satisfaction and visual quality.