Longitudinal changes in convergence behavior measured by phoria and duction tests were studied in twenty-one subjects between the ages of 35 and 60 years. The far lateral phoria and base-out duction recovery at near did not change significantly. In agreement with othet· studies, the near lateral phoria was found to shift in an exophoric direction, but only by approximately two prism diopters. A composite measure of the convergence-divergence system (convergence index scores) showed a decline, indicating a loss in ability compared to young adult standards. Wide variations were found both between and within subjects among individual test components of the convergence-divergence system.
Files are restricted to Pacific University. Sign in to view.