Are you saying that after the surgery, they forgot to put his brain back in his head?
No they removed an aneurysm 2 actually one previously not known. Hemmorhagic aneurysms. They had to remove brain tissue affected by the anoxia condition- dead cells. Don’t know which side which would affect the visual field perhaps, as the eye nerve pathways cross (Left eye to Right brain hemisphere, and Right eye to Left brain hemisphere).
Here is the 2019 assessment of then ex VP Biden (in the throngs of his chi-com/and Coup play on Trump with all the other actors then- from 2017 onward.) Pretty lousy health statistically. He’s never been very bright, and lots of cosmetic surgery, teeth caps, hair plugs (Bless you Rush- you called him “Plugs” for years). FReepers here compare to your own (males anyway) at this age.
https://go.joebiden.com/page/-/CiU2iAa4Ig_%20j5EQzueoad.pdf