This is possible and as to why it is probably the person is bored with being blind and there is no side effects and they are not mentally mad. Now with that said is it possible for a perfectly able sited person able to see the same type of images and I believe it is.
In highly intelligent people not on drugs and bored with there lot in life it is possible and probable that they also can reproduce images the same as in someone with CBS.
Years ago I had an image on a sunny day of a large black asteroid passing overhead and at the time I did not mention it because people would think I am mad. Let me tell you some people do think I am mad.
The reason for this is my mind is in the search of anything new and something that challenge the thought process. Just the other day my vision was splitting up into two parts and I was not able to see the line between one image and the one next to it. I was hallucinating and I was not on drugs I did speak to my doctor and was made to worry and they went away by them selves. I wish that I had not gone to the doctor as I would have been able to play with this and have some fun with it.
Maybe it might return and I will be able to write more on the subject.
There is a song that goes like this"there is a fine line between pleasure and pain" I have crossed this line on several occasions and I will tell you how.
I was with no sex for years and when I did get it the pleasure was so intense in my mind it was like pouring water on dry concrete and the water just spread out in all directions,well instead of water it was pain, pain so intense that it made me pass out. I went to the hospital and the doctor there just laughed and I was perplexed. He did ask if sex was involved and I said yes and you have not had in some time yes then he laughed again. I did not think it funny. Then he told me he had just read a medical journal about just this and said no way to himself. Then I walk in. I asked him what I should do and the cure and prescription was amazing MORE SEX and the beast left on its own accord.
The imagination is an amazing thing and I also think engineering is also amazing thus the name of this blog....