Anything to do with memory that works is a good thing, and there are many people with failing memories who wish they could remember something afterwards. Considering you just started analyzing it now, it is not weird that you are noticing what you can see.
If you are still concerned that your vision has a problem then you would have to see a doctor because no one can diagnose you from here.
This is actually completely normal. It's one of those things you wouldn't notice until you do one day and then start over analyzing it. I've read the explanations on the brain and it makes sense. The static at night or in the dark is actually light. Sounds crazy but few of us will ever see what it's like to be in complete darkness like the bottom of a coal mine. The image you see after looking away is an imprint from that light into your braid that's kinda burned in per se
The second imagery thing is perfectly normal especially so with people who suffer from anxiety, as they feel and notice and see things that someone who's system isn't permanently in High Alert Mode doesn't - and I've been where you are and googled so many different symptoms and, as a result, have been tested above and beyond for various different diseases and conditions and nothing has come of anything apart from iron deficiency, a couple of polyps in my colon, a hiatal hernia and HEALTH ANXIETY! (I also had a benign heart condition fixed that I had had since birth, but that was long over due since my teens). AnxiousNoMore is spot on with their advice; I feel you are fixating on different areas of the body that most probably are ticking along quite normally and nicely, because there has been a minor issues that you have happened to notice whilst anxious - people with anxiety, especially health, tend to get carried away on the internet and before you know it you end up convincing yourself that you have every rare disease and condition going and never the "normal" type ailments. Its horrible and worrying but honestly, I have had it for two and a half years, and from someone who never worried about my health and never visited the Dr, I went through a stage of thinking I had allsorts wrong with me and was never out of the damn place! I'm still here and alive and healthy apart from many anxiety and stress related niggles :)