Little lights like sparkles/firelies/floaters can be caused by a lot of different things and does not imply that you are "frighteningly close" to losing your vision. Many people get "eye floaters", including my sister who has perfect vision. Doesn't mean that people shouldn't get there eyes checked regularly in general, though. I myself get the sparkly fireflies when I stand up or move around too fast, due to high blood pressure/arrhythmia, and lack of oxygen in my blood I believe since I have a habit of taking very shallow breaths and breath holding. I don't feel like I will pass out, but because I have passed out several times in my life from lack of oxygen to the brain I know it starts with the firefly like lights and then it quickly goes to very fuzzy and grainy vision, then everything gets darker and extra grainy, like everything starts getting a purply red hue and then I pass out. I also have tinnitus that is sometimes very loud or very quiet, and the sounds change a lot. Sometimes its buzzing, ringing, and then telephone ringing sounds.

The worst thing I experience is when I close my eyes, I often see geometric patterns and forms (thats not the bad part) but sometimes I have visual hallucinations of faces so clear and so solid that after they appear in my eyes when they are closed, they "burn" there like when you look into a light and close your eyes and you see the light burned into your vision for a short while. So then I have to stare at these really clear faces of strangers burned in my vision like a bright light. They just pop into my eyes randomly when I'm trying to go to sleep, and they surprise me and sometimes scare me lol. I have no idea what it is that causes that.