Migraineurs may be at a slightly higher risk of developing certain eye problems. Although this is not usually reason for concern, it is probably reason to be thoughtful and watchful of our vision as a part of our overall health picture.
Visual aura is the temporary visual manifestation of a neurological event (spreading cortical depression) and does not include damage to the eye. Other headache disorders such as Intracranial Hypertension (Pseudotumor Cerebri) include a risk of vision problems. One type of potential vision difficulty that has been mildly associated with Migraineurs is Glaucoma.
What is the Glaucoma connection?
Recent research done in Russia and announced at the American Academy of Ophthalmology — Middle East-Africa Council of Ophthalmology Joint Meeting in Chicago, noted a correlation between normal tension glaucoma and Migraine patients with night-time low blood pressure readings. Past research showed there may be some small increased risk of a different type of glaucoma called Open Angle Glaucoma for Migraine sufferers, but the link between Migraine and normal tension glaucoma is even stronger in this small study than open angle glaucoma.
Most types of glaucoma include the hallmark symptom of increased eye pressure. Normal tension glaucoma occurs when the pressure inside the eye remains within accepted ‘normal’ limits. Despite this ‘normal’ pressure, the nerve receives damage and researchers simply don’t know why. The condition can go by several names:
- Normal pressure glaucoma
- Low tension glaucoma
- Normal tension glaucoma
Like Migraine, normal tension glaucoma is more prevalent in North American women than men.
Researchers compared the blood pressure of 12 patients with both Migraine and glaucoma. Eight of the patients had normal tension glaucoma. They compared these patients to 16 patients who had Migraine but no glaucoma. They looked at both daytime and nighttime readings of both systolic (first number) and diastolic (second number) blood pressure readings.
The researchers concluded that Migraine patients with low diastolic blood pressure at night may be at increased risk for glaucoma. The study was small however, and a larger look at the correlation would have greater impact.
The goal of the Glaucoma Research Foundation is to educate doctors and patients about glaucoma, including the benefits and drawbacks of keeping ocular pressure in the low to mid-range of what is usually considered ‘normal’ pressure.
Testing for normal tension glaucoma includes a visual examination with an ophthalmoscope. The optic nerve is identified and if it is noted to be abnormal appearing – cupped or discolored – it is reason for concern. Additional testing is necessary for a diagnosis though, with the best way to observe visual field defects being a Visual Field Test.
In a visual field test, the patient is asked to put their head in the opening of a special box. The inside of the box is full of tiny pinholes. During the test, a computer emits light thru the pinholes, one at a time. The patient looks only at one tiny spot in the center of the box and presses a button when and if they observe the light somewhere in their vision. At the end of the test, the computer gives the doctor a printed “map” of the patient’s field of vision for each eye. Deficits may not be noticed by the patient, but are easily seen on this “map”.
This research interests me because I am a Migraineur and I have visual field deficits of unknown origin. This was accidentally discovered when I was prescribed a medicine for my autoimmunity that could damage my vision. Before I began taking the medicine, I had an exhaustive eye examination including a visual field test where the deficits were easy to see once on paper.
Visual field deficits like mine can be caused by any of a number of different things — for instance, I also test positive for the genetics favoring Macular Degeneration which can affect my visual field. As yet, I do not have macular degeneration however.
At this point my optic nerve appears normal, and I hope to keep it that way. I was unable to stay on the potentially harmful medicine more than a few weeks, so it’s unlikely there was any damage as a result. I’m past due for another eye exam, and hopefully there will be no further changes. I do, however suffer from low blood pressure, especially at night. In fact, the normal readings I get are when my thyroid levels are elevated (I have Graves’ Disease), or I am in pain. My ocular pressure readings are normal, but on the top end of normal. So, the research interests me and I’ll probably take this study to my ophthalmologist and see what he says.