Fixation Switch Diplopia: An Evaluation of Suppression

Abstract

We evaluated the sensory status of 20 patients who met the criteria for diagnosis of fixation switch diplopia. We were further able to assess the suppression zone by binocular perimetry on the Lees screen in eight patients. In each patient, a small central suppression scotoma was demonstrated in the deviated eye using fusable fixation targets. No suppression scotoma was identified in the preferred eye in the diplopic state. In all patients, a secondary deviation of minute proportions from the primary deviation was detected on the Lees screen. Our results suggest true fixation switch diplopia is due to a micro secondary deviation too small to detect with prisms.

• diplopia
• strabismus
• scotoma