Hello James: Welcome to NeuroTalk! I'm afraid I can't really address your concerns. I'm nowhere near 90 yet. But I am an older person. My head has taken a beating over the years. (I'll spare you the details.) I haven't experienced anything like this. (I almost wish I had. I just seem to get dumber as the years go by.)

One thing I have had, which I think may have been the result of some of the damage I've done to my head, is that I had a detached retina in one eye. I can't say for certain that the two things were related. But it is my belief that they were. Given your experience of seeing orange & yellow colors appearing out of nowhere, it might be worth having your eyes checked out by an ophthalmologist.