New Insight: Preperimetric Homonymous Hemianopia.

A 29-year-old man was referred to our institution for a visual function evaluation 14 months after a traffic accident. His best-corrected visual acuity was 1.0 in both eyes. Brain magnetic resonance imaging revealed multifocal encephalomalacic changes in the left frontal and left temporal cortical and subcortical regions. Focal encephalomalacic changes in the left basal ganglia were observed in association with passive dilation of the left lateral ventricle, due to the presence of old haemorrhage. A non-specific scattered scotoma was found in the left eye. Spectral-domain optical coherence tomography (SD-OCT) was performed and peripapillary retinal nerve fibre layer (RNFL) thickness was reduced in the superotemporal and inferotemporal quadrants of the ipsilateral eye and the temporal and superonasal quadrants in the contralateral eye. SD-OCT revealed retinal ganglion cell degeneration extending from the nasal retina to the fovea in the right eye and from the temporal retina to the fovea in the left eye. In this patient, retrochiasmal defects resulted in RNFL defects corresponding to homonymous hemianopia without a visual field defect. Therefore, SD-OCT can be used to rule out a preperimetric homonymous hemianopia. This information would help to confirm the existence of an optic tract lesion before visual field defects.