Light rings around eye vision

For the past 4 days I have noticed an odd ring of light around the outside of my vision. Sometimes it is accompanied by a headache, but I have headaches regularly. I have no idea what could be causing this, it comes and goes. Usually it is just a white flashing ring, kind of like a throbbing sensation. Any ideas?

[Sandra M Brown, MD]

The two possibilities are migraine aura or tugging on the retina (the nerve layer that lines the inside wall of the eye).  If the ring of light seems to throb, expand and contract, change shape, develop a "vapor trail" or change colors then almost certainly it is a migraine aura.  If it just seems to be an amorphous glowing light that is always in the same spot, it could be retina trouble.  If the latter, you should be evaluated by an Eye MD promptly.

[SlimRed]

Thanky you!