Hello,
When I am in a darker room and I look towards the window (the sky), but not too bright window, I see a bright small disc for a fraction of a second after I open my eyes. The same thing if I cover and then suddenly uncover any of my eyes. If the light is dimmer, the disc is larger. It's in the center of my vision. At the exact location, in completely dark environment, with my eyes closed, I frequently see a small brighter area. Is this a normal phenomenon, or may indicate some disease? Thank you.