See lights flash in vision shapped like veins

Sometimes during exertion I will see a light flash, shaped like veins in my eye. 

It only ever flashes once per time, and always with m heart beat, and never if I'm being sedentary. 

Iv not thought anything of it till now so iv never mentioned it to my doctor, but I have had an eye exam in the last month and everything  came back fine.

How old are you? It could be the Vitreous tugging on the retina. I have the flashes in my vision and my Viterous is tugging on my retina, I also have a partial PVD.

I have flashes too but my optometrist didn't see anything. I'm waiting to see if it goes away but I do have an MRI Friday of this week.

Im 23, but iv been seeing these flashes since I was maybe 18. 

They dont happen very often, but often enough for me to be a little concerned