Hi,
When i look at a bright background like the sky, and flick my eyes to the left, a momentary crescent of light appears in my left eye which appears to be in the same part of my visual field each time. It's like an afterimage and only lasts a split second. Not sure if this just started today.
I have a huge number of floaters in both eyes that have got steadily worse over the years. Possibly related to that?