horror fusionis

A rare binocular vision anomaly characterized by an active avoidance or suppression of bifoveal fusion. Patients experience constant diplopia but are unable to fuse or tolerate the double images. It often presents in childhood with long-standing strabismus or amblyopia and may involve abnormal cortical wiring or sensory adaptations. Treatment is difficult as prisms, occlusion, or surgery typically cannot eliminate the diplopia. Over time, patients learn to ignore or suppress one of the images.