Primary Visual Area

Left primary visual area damage that also includes nearby splenium may yield alexia without agraphia. There is right-sided hemianopia, though the intact right visual areas cannot communicate with the left fusiform gyrus (see below) due to the damaged corpus callosum, producing a preserved ability to draw but not write (Rupareliya et al, 2017)

Bilateral damage to primary visual cortex (V1) results in subjective experience of blindness, though due to intact striatal visual pathways, patients can still score above-chance detecting moving stimuli, a term called blindsight (Ajina and Bridge 2017). Riddoch’s phenomenon is a subtype of blindsight in which patients report some awareness of movement in their otherwise blind field (Danckert, Tamietto, and Rosetti, 2019).

References

Ajina, S. & Bridge, H. Blindsight and Unconscious Vision: What They Teach Us about the Human Visual System. Neurosci. Rev. J. Bringing Neurobiol. Neurol. Psychiatry 23, 529–541 (2017). https://pubmed.ncbi.nlm.nih.gov/27777337/

Danckert, J., Tamietto, M. & Rossetti, Y. Definition: Blindsight. Cortex 119, 569–570 (2019). https://pubmed.ncbi.nlm.nih.gov/30808548/

Rupareliya, C., Naqvi, S. & Hejazi, S. Alexia Without Agraphia: A Rare Entity. Cureus (2017) doi:10.7759/cureus.1304. https://pubmed.ncbi.nlm.nih.gov/28690938/