I keep getting stars too im 39+3 iv had blood pressure checked and water for pre eclampsia and I got the all clear so I have no idea what is causing it :-( but you should call your midwife and let her know so you can be 100% sure its not pre eclampsia
good luck
I've heard that impaired vision could be a warning sign for pre eclampsia. Maybe give your doc a call and see if they think it's something to be concerned about.
Sounds like blood pressure, I sometimes see spots thought I was going crazy tbh, take yiur time getting up and maybe have a word with your mw