Tony Brune, DO, Departments of Neurology, The Johns Hopkins School of Medicine; Daniel R. Gold, DO, Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, The Johns Hopkins School of Medicine
The assessment of convergence includes measuring alignment at near versus distance (see video, https://collections.lib.utah.edu/details?id=187677), near point of convergence and convergence amplitude. Near point of convergence is assessed by bringing a fixation target toward the bridge of the patient's nose. The distance at which binocular fixation is lost or diplopia is experienced is recorded (also see video, https://collections.lib.utah.edu/details?id=187671). Convergence amplitude is determined by placing base out prisms of increasing power over one eye while the patient views a near target. The highest prism power before binocular fixation is lost or diplopia is experienced is the convergence amplitude. Although the specific diagnostic criteria for convergence insufficiency may differ, typically the diagnosis is made when: 1) the near point of convergence is greater than 10 centimeters, 2) the convergence amplitude is less than 15 prism diopters, and 3) there is an exodeviation greater than 10 PD at near, or the exodeviation at near is at least four prism diopters greater than what is recorded at distance.
Spencer S. Eccles Health Sciences Library, University of Utah