Diplopia, also known as double vision, is the simultaneous perception of two images of a single object. These images may be displaced horizontally, vertically, or diagonally in relation to each other. Diplopia has a diverse range of ophthalmologic, infectious, autoimmune, neurological, and neoplastic causes. A key pathological emphasis should be placed upon the Trochlear nerve (fourth cranial nerve) which causes weakness of the superior oblique muscle, resulting in a downward and inward gazing of the eyes.
Diplopia is one of the most troublesome visual disorders a patient can experience. The ability to read, walk and perform common activities is suddenly disrupted. The management of double vision may include prisms, orthoptics, therapy, eye muscle surgery and occlusion.
Binocular diplopia is double vision which occurs as a result of the misalignment of the two eyes relative to each other, such as occurs in esotropia or exotropia. In such a case while the fovea of one eye is directed at the object of regard, the fovea of the other is directed elsewhere, and the image of the object of regard falls on an extra-foveal area of the retina.