FEB 10, 2022
A review of cases from a single practice in the United States was conducted to determine the incidence of divergence insufficiency (DI) esotropia over time.
This is a retrospective study of the incidence of DI esotropia over 41 years in the senior author’s practice. Patients were classified as having DI esotropia if the distance esotropia angle was ≥5Δ than the near esotropia angle; 646 satisfied this definition. Those who had thyroid eye disease, scleral buckles, trauma, neurologic diseases, or atypical misalignment were included in the incidence calculations but not categorized as having DI, even if distance angle was greater than the near angle.
The rate of DI esotropia increased significantly from the first half of the 41-year study period to the second half, from 11.8% to 29.4%. Likewise, in the first half of the study, 5.3% of patients with acquired esotropia wore progressive addition lenses, increasing to 16.8% in the latter half of the study. Advancing age and progressive addition lenses were identified as risk factors for the development of DI esotropia with multivariate logistic regression analysis. It is thought that progressive lenses result in a chronically increased convergence tonus from underuse of the lowest and strongest portion of the addition lens.
This is a retrospective study, and all cases with a distance > near disparity of ≥5Δ likely do not fall into the same category, such as a lack of differentiation between sagging eye syndrome and heavy eye syndrome.
Results from this study suggest that patients with DI esotropia are presenting more frequently to comprehensive ophthalmologists and strabismus surgeons. This pattern of esotropia often prompts further investigation with imaging as well as a nuanced surgical approach. The increased incidence of DI esotropia, as well as association with progressive addition lenses, will impact many patients and their treating ophthalmologists.