My dad died of Glioblastoma when I was a teenager. He first noticed it as a sudden worsening of vision, followed by a breakdown of spatial relationships. My mom's boyfriend's best friend died of it too.

It's a horrible disease and the worst part about it is that it always comes back. Surgery and treatment might buy you 5 good years if you catch it early and it isn't as malignant. But it will always come back and kill you.

If anyone has any illusions that human personalities are made of more than the meat in our heads, watching someone die of a brain tumor will disabuse you of them. Bits of them disappear, and the remaining bits misfire and overcompensate for the bits that aren't there.

For anyone reading this, if your vision suddenly gets worse, don't just get new glasses. Go see a doctor. Most of our brain is devoted to visual processing, and if something isn't right it usually manifests there first.