Sudden Onset Diplopia

Sudden onset diplopia can be the result of underlying systemic or neurological conditions. I present the case of a 32-year-old woman with a previously diagnosed convergence insufficiency, who developed sudden diplopia. Physicians ruled out systemic and neurological conditions, but were unable to resolve the diplopia. Functional optometric examination with vectographic targets showed Intermittent Central Suppression (ICS). I hypothesized that the ICS served to momentarily negate the sensory lock required for binocular fusion in a patient with fragile convergence ability. Correcting the ICS using electronic rapid alternate occlusion on a home therapy basis improved fusional convergence, and the diplopia was significantly lessened. There was no standard direct therapy for the convergence insufficiency. The alternate flicker of rapid alternate occlusion is a strong motion stimulus. Since a strong motion stimulus in isolation eliminated the suppression, this supports the theory that magnocellular defect is responsible for