Do you see black things floating around? Do you get a headache with these episodes? How is your vision othewise?
Do you see black things floating around? - No black things only areas of fuzziness
Do you get a headache with these episodes? - No headaches
How is your vision othewise? - fine, slightly myopic (glasses for TV / driving) but nothing out of the ordinary.
It sounds like what you are experiencing is ocular migraines. These typically start with flashing or lightning on the periphery. Some people may even lose part of their vision (similar to a stroke). This may or may not be followed with a headache. The episodes usually last 15-20 minutes.
There are three types of migraines. The ocular migraine as described above. There is the migraine headache. And there is the classical migraine (visual symptoms followed by a headache). They are treated the same with the same medications.
You should have your eyes checked to make sure the retina is OK. But you should also consult your primary care physician or neurologist about treatments for these migraine episodes.