One of the most common of those symptoms are shimmering, glaring blind spots, sometimes colored that can cross the visual field over a period of 15 or 20 minutes. Sometimes the visual abnormality has a zig-zag geometric pattern. Sometimes, it's just a blind spot. It's important that if that is the only symptom you have, that you ask a physician to make certain that your diagnosis is nothing more than migraine. Although, it is unusual, your symptoms without headache, are reported by many people who have nothing more than migraine.
Some people are able to control their headaches dramatically well with biofeedback.
And can reverse a headache and prevent headaches with regular biofeedback exercises. Other people find it less helpful. It is particulary valuable when used in conjunction with other treatments including medicines. They are extremely safe for most people. And long-term use has not been associated with serious or significant adverse effects.