Bitemporal visual field defects mimicking chiasmal compression in eyes with tilted disc syndrome.

BACKGROUND: Tilted disc syndrome (TDS) is a congenital optic nerve coloboma occurring from embryonic dysgenesis. Several features characterize TDS, including an inferiorly located conus, situs inversus of the major retinal vessels, and an anomalous disc shape. Commensurate with axonal dysgenesis, visual field defects may often occur from TDS, the most common of which involve the temporal and superior temporal visual field. These visual field defects can mimic those seen in chiasmal compression from a mass lesion. CASES: Five patients from New South Wales, Australia, with distinct TDS and bitemporal visual field defects on frequency doubling threshold perimetry seemingly respecting the vertical hemianopic line are presented. Neuroimaging and medical evaluation of each failed to show intracranial chiasmal pathology in any patient.
CONCLUSIONS: TDS can present with visual field loss resembling that seen in chiasmal disease. Although most cases of temporal visual field loss from TDS do not respect the vertical hemianopic line and are not true quadrantanopsias, there are instances in which this does occur, likely caused by the testing modality used. It is essential that patients with suspected intracranial pathology undergo immediate neuroimaging, even in the face of TDS.