I see a flashing light in my eye. what could this be?

Photopsia: Or light flashes, are very common symptoms. They occur when the vitreous jelly in the back of the eye shifts and pulls at part of the retina. Usually, once the vitreous separates from the retina, the light flashes resolve. If you develop some floaters or dark shades coming over the vision from the side, then this could be an indication that there is a retinal tear or detachment. See an eye doc.