start with a medical eye exam by an ophthalmolgoist. Find one at www.aao.org
JCH MD
I did today.. and she said everything is fine.. she dilated my eyes and said everything is healthy...but im still experiencing the light little circle flash
Then the most common cause would be "entopic phenomena" to learn more use the search feature or archives. Also go to wikipedia.com and read their article on it.
JCH MD