Diplopia: an Overview
Diplopia or seeing double, is a symptom, that may have a lot of causes - neurological, ophthalmological, and psychiatric as well.Diplopia is common visual concern. It can be not just a subjective discomfort, but also the symptom even the first one of a life-threatening condition - stroke, brain edema.A single vision is formed in the brain due to the fusion, that is the mechanism of merging images from both eyes. The peripheral, or motor, component of the fusion is provided by the ocular motor system, which is responsible for conjugate and precise movements of the eyes, in which the visual axes of both eyes are aligned, and the object is seen by corresponding points of each retina.The causes of the impaired mobility of the eyes can be localized at any level - cranial nerve nuclei in the brain stem, cranial nerve paths inside the skull, neuromuscular synapse, external muscles of the eye in orbit, but disruption at any level produces the disorder of eye movement, and diplopia will manifest.Disorders of the central (sensory) mechanisms of fusion (the visual cortex) - can also lead to double or multiple visual perception - cerebral polyopia.The diagnostic search is complex and requires knowledge of the brain anatomy, which, along with the data of a neurological and general examination as well as medical history, will reduce the number of additional examinations and speed up the process of diagnosis and the start of specific treatment.The article provides the detailed anatomical courses of the oculomotor (III), trochlear (IV) and abducens (VI) nerves, the possible causes of their lesions at different levels and clinical features that help the clinician in localizing the site of involvement during the routine neurological examination. The article also mentioned other possible causes of diplopia, such as eye muscles, neuromuscular synapse, and supranuclear structures disorders.Laboratory and instrumental methods of research, as well as involvement of related specialists can also play a key role in the diagnosis.