Melanie...I have spent some recent time researching visual issues...
I personally was blessed with vision therapy...tho, based on the status of any patient...it may not regain all of our usual vision...nor does it after/later protect the involved cranial nerves...
What all did the doctor(s) explain; e.g. which cranial nerves (left and/or right) were / are affected?
You may want to ask specifics about it; the anatomy of it; the name of it...
The cranial nerves involved in vision: cranial nerve II (CN 2): optic re: retina
CN 3: oculomotor
CN 4: trochlear
CN 6: abducens
There three work separately and together for movement / control of our eyes...
You may want to search on-line: cranial nerve anatomy on to: cranial nerve functions ...
There are wonderful sites...and, some so much easier to read...so you may want o browse...and /or you may have different info from your mum's doctors...
Cortical visual impairment... same as cortical blindness (one word newer than the other?)
Other terminology you may want to research:
Homonymous Hemianopia (aka hemianopsia) ...
Bi-lateral Hemianopia
Bi-nasal hemianopia
Bi-temporal hemianopia (one of high interest to me)
Midline Shift ...re: cranial nerves ...
Then, may want to pursue: Cortical Blindness after contrast-enhanced CT
http://www/ajnr.org/content/24/6/1114.full
It notes that transient cortical blindness is an uncommon but well-known complication following cerebral-angiography...As this was written in 2003...there is not a vast list of data on procedural improvements to reduce complications / adverse events...re: visual or auditory ...
You may have the diagnostic data from your mum's doctors that would be easier for you to peruse online...perhaps you can call/ask...IF the term cortical blindness was not explained clearly...
Melanie...I am so yet in the research...re: the cerebral arteries and their connection/interconnection to the cranial nerves...I have no expertise ... just data that is so important to me... (hopefully...to others for their own research and questions to their doctors)...
Many of us will so cherish your sharing whichever results you achieve from your mum's doctors with us...
Pat