Band atrophy of the optic nerve: A report on different anatomical locations in three patients.

Lesions of the optic tract are accompanied by various signs that help to distinguish them from hemianopias located posterior to the lateral geniculate body. Band optic nerve atrophy is one of these signs and typically occurs contralateral to the optic tract lesion. We report on three patients with band atrophy in the fundus of the eye. These three patients present examples of how three lesions with different anatomic locations can cause band atrophy of the optic disk in similar ways. In these cases, the presence of relative afferent pupillary defect (RAPD) and band atrophy becomes important in identifying the injury to the optic tract, because when the hemianopia is complete visual fields do not allow distinguishing optic tract lesions from occipital lesions. The RAPD occurs in the eye in which the visual field defect is greater. In this paper we review the different theories about the explanation for RAPD in patients with optic tract lesions. It does not seem as simple as the anatomical differences between the number of fibers that decussate in particular cases, rather, it is associated with the difference between the sensitivity levels of the two functioning hemiretinas.