Hi again do20,
The best person to help you with information regarding your own situation would be your doctor or perhaps even your family who might have medical records from when you were born or very young.

I had a look around some medical journals and found mostly what you mention in your post regarding lost visual memory due to accidents or other health issues.

There were a couple of articles that didn't actually relate to your situation, but one was regarding congential blindness and visual memory (this basically was showing the positive effects or differences that blindness can have on memory) and the other was regarding visual memory-deficit amnesia.