My Mom is seeing purple around things and she said she like she is in a fog. What is this?

When someone doesn't have dementia, fog and tunnel vision can go with anxiety and depression. It's like standing on the outside looking in, with a cast over and around everything. This might not be relevant for someone in more advanced stages of dementia. You can talk to her doctor about it and see if there is a solution that will make her feel better.

What does the Nurse Practioner or Doctor at the NH say might be causing this?