You need to get yourself examined by an ophthalmologist to rule out potential retinal detachment
"Flashes and flickers occur from inappropriate activation of the retinal photoreceptors or the vision-related cerebral cortex.
The major cause of inappropriate photoreceptor activation is tugging by an aging vitreous. In late middle age, the vitreous normally detaches from the retina. As it does, it may tear a hole in the retina. If liquid vitreous seeps under the hole, the retina may detach and destroy vision. This causes brief white flashes in the peripheral field. Blunt trauma to the head or eyes can also set this off ("seeing stars")."
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