Induced Convergence-Retraction (Convergence-Retraction Nystagmus)
Induced convergence-retraction (convergence-retraction nystagmus) is not a true nystagmus; rather, the abnormal eye movements are saccades. In children and adults, induced convergence-retraction is part of the dorsal midbrain syndrome, which is associated with paralysis of upward gaze, eyelid retraction, and pupillary light–near dissociation. In children, it commonly occurs secondary to congenital aqueductal stenosis or a pinealoma. The phenomenon is best elicited by having the patient attempt an upgaze saccade (Video 13-6) (eg, track a downward-rotating optokinetic drum). Co-contraction of all horizontal extraocular muscles occurs upon attempted upgaze, causing globe retraction. Convergence also occurs, because the medial rectus muscles overpower the lateral rectus muscles (voluntary convergence, however, may be impaired).
Induced convergence-retraction (convergence-retraction nystagmus).
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.