25th December 2023

Exceptional visual field defects

Rarely, intracranial insults may give rise to unusual visual field defects that may mimic an intra-ocular or pre-chiasmal insult. There are two circumstances of note:

1. Bilateral occipital lobe lesions: will give rise to bilateral altitudinal visual field defect mimicking retinal or optic nerve head lesion. Full dilated fundus examination is recommended to exclude local causes. Neuroimaging is diagnostic. Patients are at risk of cortical blindness syndrome.
2. Unilateral temporal crescenteric visual field defect: The nasal visual field extends to 60 degrees from fixation, whereas the temporal field extends to 90%. This leaves an area of the temporal visual field that has no nasal correlate in the contralateral eye, represented within the parieto-occipital sulcus. Damage in this area of the visual cortex leads to a monocular, contralateral temporal crescent defect.

References

• Ali K The temporal crescent syndrome Practical Neurology 2015;15:53-55.
• File [modified]: Hemianopsio eo.png. Wikimedia Commons [Internet]. Commons.wikimedia.org. 2021 [cited 15 May 2022]. Available from: https://commons.wikimedia.org/wiki/File:Hemianopsio_eo.png
• Newman RP, Kinkel WR, Jacobs L. Altitudinal Hemianopia Caused by Occipital Infarctions: Clinical and Computerised Tomographic Correlations. Arch Neurol. 1984;41(4):413–418.