In this past year I have been having a problem with my eyes. I could be sitting still or walking and suddenly I get this jagged line in the center of my vision sometimes in both eyes and sometimes in just one. It takes about 20 minutes, but it goes from small to large moving outward from the center. I can watch it spread out and along the jagged line is a blind spot. I seem to lose sight along the line. When I close my eyes I can still see it moving outward. What could this be? I had one today and realized that yesterday I had a migraine. Could that have anything to do with it and do I need to seek some help soon?
Your question is a very interesting one, and is an almost textbook description of the visual aura of classical migraine. The onset of the disturbance near the middle of vision, the jagged appearance of the line, it’s slow spread outward, the temporary blindness behind the line and the duration of 20 minutes are all part of the classical description. Also typical is that the phenomenon continues even with the eyes closed. Other causes of temporary blindness produce a loss of vision which is not apparent when the eyes are closed.
It is interesting though not very unusual that you do not have a migraine headache immediately following the visual phenomenon, but that you do have migraines at other times, I presume without any aura. Having migraines of different types during one’s life is not rare, and a person may have a mix of “classical” migraines with auras, and “common” migraines without auras. You may find that if the visual attacks you are having continue, they may be followed by headaches in the future. I once had an aura almost identical to the one you describe, but only in one eye. It was not followed by a headache, and I have never had another. Strange.
The causes of migraines are still unknown. What is known is that they seem to be precipitated by a nerve discharge from a part of the mid-brain to the occipital cortex, the portion of the brain at the back of the head which receives impulses from the eyes and which puts those impulses together to form the images that we see. The migraine aura is accompanied by a “spreading depression,” an area of reduced blood flow on the surface of the occipital cortex that slowly spreads out, as the line you describe spreads across your eyes. Finally, the trigeminal nerve, which carries sensation from the face and head is stimulated and creates the typical, throbbing, one-sided headache, often with nausea.
Migraines commonly have triggers, such as foods; alcohol, chocolate and blue cheese being frequent offenders or, sleep deprivation, stress, exercise or drugs such as nitroglycerin. Birth control pills may make the headaches more frequent or more severe. Although strokes are rare in young women, they do occur more often in women on birth control who have migraines, and an increase in frequency or severity of headaches in a woman on the pill is usually a reason to stop them. Cigarette smoking increases the risk of stroke even more. The low estrogen pills have the smallest increase in stroke risk, and the progestin-only pills have no increased stroke risk, but are seldom used because of irregular bleeding.
Some women get migraines at the time of their menstrual periods, and despite what I said above, one strategy to prevent them is to take birth control pills continuously, with no placebo pills every three weeks, and therefore no menstrual period. This method of taking the pills is safe, and is increasingly being used in other situations where problems are related to the menstrual period, like endometriosis. Usually after 3 to 4 months of continuous pills, a woman will experience breakthrough bleeding, and should stop the pills for 4 to 5 days to allow a period to occur, and then resume the pills. This strategy should be stopped if the woman begins having more frequent or more severe migraines as I noted above.
There are now many effective treatments for migraine attacks, and many possible drugs to prevent the attacks if they are so frequent that taking a daily preventive medicine would be desirable. Sumatriptan, available as pills and as a self-administered injection or nasal spray, and its recently approved relatives are very effective in treating the headache once it begins. Propranolol, verapamil, amitriptyline and valproic acid are often used to prevent the headaches. These have to be taken daily to prevent the headaches and will not stop a headache once it has begun. For someone like you who are having auras without headache, treatment may not be necessary, but you should probably report this change in your symptoms to your doctor, and perhaps get better treatment for your regular migraines when you have them. You should be reassured that the auras you are having do not damage the eye since they are not actually occurring in the eye itself.