photopsia
Flashes of light often noticed in the edges of the visual field. Photopsia can have many causes, including mechanical (rather than visual) stimulation of light-sensitive cells (photoreceptors) in the retina. For example, a detached retina can cause photopsia when the retina pulls away or detaches from tissue in the inner back of the eye. A vitreous detachment with accompanying photopsia can occur when the eye's gel-like interior begins to shrink and pull against the retina. Photopsia can be accompanied by a shower of spots and floaters.