I see bright light in my eyes and then shortly after pounding head ache. this happens a lot. why?

Migraine : Scintillating schotomas, flashes of light, are part of the ocular migraine symptomsthat occur before the headache.. It sounds like a typical migraine. Patients can have spasm of the arteries at supply the eye and get these symptoms without headache. If it persists or interferes with her daily activities she should go to her primary care doctor for an exam and treatment.