Congenital optic tract syndrome.

We describe two patients with complete homonymous hemianopia who were unaware of their visual field defects. The clinical impression of an optic tract syndrome was confirmed by magnetic resonance imaging, which showed absence of the corresponding tract in each case. The pathogenesis of congenital absence of the optic tract is unclear but it could represent either a primary failure of development or secondary atrophy due to focal injury during the perinatal period.