This is the absence of verbal report of stimuli presented in the visual left half-field in the absence of hemianopia. It may occur after callosotomy (complete, or partial involving only the splenium), and represents a visual disconnection syndrome.
Zaidel E, Iacobini M, Zaidel DW, Bogen JE. The callosal syndromes. In: Heilman KM, Valenstein E (eds.). Clinical neuropsychology (4th edition). Oxford: OUP, 2003: 347-403