Diplopia

Abstract

Binocular single vision is based upon the fusion of two retinal images, one perceived by each eye, into a single percept. This phenomenon is called fusion, one of the stages of an intricate system of processes taking place in the brain. In order to direct our eyes to a focus of attention, six extraocular muscles per eye-each innervated by three extracranial nerves-control ocular movement. This operating system can be disrupted easily. Orbital diseases may impede the function of these muscles and nerves leading to strabismus and, eventually, (gaze-dependent) diplopia. Orthoptic investigation and diagnosis can help in the treatment of this group of patients. Orthoptic investigation is constructed by several steps which will lead to a full picture of the binocular system, and includes determining ocular deviation, binocular function, and ocular motility. Based upon these results, the orthoptist may provide temporary measures, such as prisms or occlusion to lessen the burden of diplopia. In case of lasting diplopia, strabismus surgery can alleviate part of this diplopia. However, restricted eye movements, incomitant deviation, and severe cyclotorsion may hamper the field of binocular single vision, even despite the availability of various surgical options. Careful explanation and a multidisciplinary treatment of orbital patients is necessary to guide them through the treatment process.