The original post is a year old now, but this may help new visitors with similar problems. I have 20/20 vision and despite having some sort of translucent floater in my right eye, there’s “nothing wrong” on clinical exam.
1) I have found that doing ‘eye exercises’ for a few days, specifically looking at and focusing on objects in the far edges of the visual field, reduces this problem for me. I generally focus on something, then slowly turn my head right (for instance) until experiencing some nystagmus. I then try to focus without my eyes shaking, which works for a short time (~20s) until my eyes are exhausted, then repeat the process in the other directions (left, up, down, etc). This causes significant exhaustion, nausia, and an overall uncomfortable feeling, so I would only do this at night before going to sleep. Over-doing it will make for a bad morning, too. It seems to increase the visual area available before nystagmus starts, and after doing this for about 3 days my eyes stop shaking for no reason during the day. I have to repeat the process once every few months when the random shaking returns and gets in the way of my life. This may or may not work for you as we all have different problems. As for cause, Dr. Diana would have to comment on that!
2) See “visual snow”. I have also had this for as long as I can remember, and have never noticed seeing anything in perfect clarity in my life. In extremely dark or bright environments, these “spots” take on a primarily red colour, whereas the rest of the time one could say they’re black or otherwise “not coloured”.