Alberta is a land of ups and downs when it comes to weather (you may have noticed this recently with our ‘spring’ weather). +20C in December? -10C in July? -40C on Tuesday and +20C on Wednesday? These are just normal weather patterns here and as anyone who gets migraines can tell you it’s not fun. The wild temperature swings wreak havoc on our systems and can cause some funny things to happen.
You’re busy doing your thing when suddenly your vision goes a little funny. You may notice shapes or colours or motion in your vision, not right in the middle but just off to the side. The effect may get larger or smaller. It may move faster or slower or not at all. Sections of your vision may simply vanish and go dark or you may still be able to ‘see’ but things you know should be there just aren’t visible to you anymore (like whatever is supposed to be there pulled a chameleon on you and has become invisible). You may have never had this happen but if these symptoms sound familiar you’re not alone. If you had this happen and didn’t panic at least a little I’m impressed. I’m an optometrist and when this happened to me even though I fully recognized my symptoms and knew what was happening my heart rate bumped up a few notches. This event is known as an ocular migraine.
The term ocular migraine implies that you should get a headache afterwards. That’s not always the case. Some people do have migraine headaches after seeing these images in their vision but not everyone. You may have heard of people getting an aura that tells them they’re about to get a migraine. That’s essentially what this is. Auras or 'ocular migraines' usually last about 20 minutes and are followed by a return to normal vision and depending on the person a headache, a migraine, or absolutely no pain.
So, what the heck is going on? It’s not certain but what is believed to happen is that for some reason the blood vessels in the visual cortex (the very back of your brain… about as far from your eyes as you can get and still be in your head) shrink way down and not as much blood is getting through as before. This lack of blood flow means your brain can’t function the way it would like and you start to experience really bizarre things in your vision. It takes your brain, usually, about 20 minutes to figure out this isn’t normal at which point the blood vessels do one of two things. They either return to their normal size, blood flow returns to normal levels and you stop feeling like you ate a brownie you shouldn’t have OR the blood vessels expand to their maximum size stretching themselves to be as big as they can. It’s that extreme stretch that causes the horrible pain people experience with migraines. In some cases the vision changes can last longer than 20 minutes. This usually occurs if someone completely panics causing an adrenaline surge. The resulting stress levels can cause the visual changes to linger for about an hour.
Here’s the real kicker. There’s not much you can do about this. We think that all those blood vessel antics are caused by the same things that cause migraines… so, almost anything (certain smells or foods, weather patterns, stress, lack of sleep. The list goes on and on). Migraine medication can be helpful if a person is getting ocular migraines all the time and it’s seriously interfering with their life but otherwise we just recommend that a person sit back and enjoy the show for 20 minutes. If you’re driving it is strongly recommended to pull over and wait it out. These vision changes are temporary and do not cause any damage to your eyes or your brain.
So rest assured that if you have been properly diagnosed with an ocular migraine your eyes are safe and sound. I would love to leave it at that but there is one more thing. Not all flashes in your eyes are harmless. Retinal holes, tears and detachments can cause symptoms including flashing lights in your vision, floaters and a curtain moving in and out of your vision. These flashes do not go away in 20 minutes and generally are noticed at the very edge of your vision. Retinal detachments are extremely serious and cause permanent loss of vision. If you experience flashing lights in your vision of any kind it is best to have it properly checked by an optometrist. These visits are considered medically necessary and are fully covered by Alberta Health Care. I would advise against taking a risk. If you see flashing let an optometrist have a look at your retina to confirm everything is normal.