Every now and then I get a head rush kind of feeling, with lots of pressure pushing on my eyes making them feel like they are bulging out of my head. It causes a large dark perfectly round spot in my vision in each eye. It happens fast and doesn't last very long. I haven't been able to associate it with any physical changes. This has happened for many years now, but is occurring more frequently now.
Does anyone have a clue what this might be? Thanks