Every one is making an incorrect assumption about vision, most visual processing does not happen in the Eyes in fact the eye simplifies images by negative lateral inhibition, so that what leaves the eyes is a sort of line drawing of the seen (oversimplification but bare with me). Most of the processing is done in the visual cortex, which in this lady was intact. The visual cortex is the product of 500 million years of vertebrate evolution and represents the hard-wired phylogenic memory that we all carry. It is to some extent autonomous and in the event of no input from the optical nerves does not whither and die, but becomes involved in other processing jobs.
So there is another possible explanation for this result.

PP