Photophobia can be a common symptom for patients with migraine. For such a common symptom, photophobia has lacked careful research and has been misunderstood until recently.
What is photophobia? Sometimes individuals think the light is “too bright”—meaning there is an increase in the sense of light. Others will complain of pain associated with the light (the light hurts) . Everyone has some level of light sensitivity---think of going from a dark movie theatre to a bright sun-shine day; that light sensitivity and discomfort is usually brief. But some people have that sense of pain and brightness every day, and some people find that even normal light causes pain or discomfort. Photophobia is a very common symptom during migraine—in fact it is one of the criteria used to diagnose migraine. However, some individuals have photophobia every day. Some people may be even disabled by this symptom.
It is clear that the brighter the light, the more discomfort is felt. The wave length of light (color) may also be important—blue light causes more trouble than other colors of light. The amount of light that a person lives in will affect this symptom. If one lives in darkness all of the time, then light will be sensed as being even brighter.
No one knows the exact area of the brain that causes light sensitivity. However recent studies have helped to elucidate this symptom. Light is carried in the visual pathways to the brain by way of the retina. In the retina there are cells that detect light and formed vision (like reading letters or seeing pictures) called cones that project to the visual pathway in the brain. There is a second system, the melanopsin system that does not participate in formed vision but specifically senses light. There are fewer of these cells in the retina of the eye, but once these cells get turned on, these cells do not turn off. We believe that both of these cells may set up a sense of brightness that can cause trouble. We now also know that these cells do connect with the trigeminal system in deep brain centers—and therefore can cause pain. The melanopsin system also explains why people who are blind (no formed vision) can still experience photophobia.
While migraine is the most common condition associated with continuous photophobia, there may be other causes of photophobia. Trigeminal pain fibers are in the cornea, the iris (colored part of the eye), and even the back of the eye. Even dry eyes may cause light sensitivity in some individuals. Other neurological conditions can also cause the symptom including pituitary tumors, meningitis (inflammations of the covering of the brain), The two most common causes of photophobia are migraine and blepharospasm (a movement disorder that causes frequent blinking). Dry eyes can complicate chronic photophobia, so a visit to the ophthalmologist may be helpful.
Once the correct diagnosis is made, there are treatments. For example, if there is dry eyes, dry eye treatments can be used (tears, gels and ointments). Intermittent photophobia associated with migraine usually respond to acute medications such as triptans, non-steroidals. Preventive treatment of the migraine may help reduce chronic photophobia.
Tinted lenses, in particular FL-41 tint, and blue-blocking lenses, and red lenses have been reported to decrease and improve light sensitivity. These can be obtained without a prescription by talking with your oculist. Sunglasses outside frequently help with light sensitivity in the sun.
Co-morbidities of photophobia including sleep disorder, depression and anxiety may require treatment as well.
Frequently Asked Questions
1. Why do I have light sensitivity?
There are many causes of light sensitivity. That is why your medical provider will do a careful examination to determine the contributing factors. The most common causes of light sensitivity include migraine, blepharospasm, and dry eyes.
2. What can I do to make my light sensitivity go away?
First, adequate treatment of the cause is important—that means if you have dry eyes you should treat that symptom aggressively. Second, be sure that you do not keep yourself in the dark—e.g. NO darkened rooms, no darkened windows, slowly increase the amount of light in your environment so that you are more tolerant of the light. Get adequate sleep and treat any depression or anxiety which can make your symptoms worse.
3. Will tinted lenses work for me?
There is no way to be sure that you may or may not benefit from tinted lenses. Sometimes it is trial and error. Using the least amount of tinted lenses while you are inside is the best because the darker things are the more the light will bother you.
4. How does FL-41 work? Although we are not really sure why FL-41 improves light sensitivity, we think it is has something to do with the wavelengths of light (color) that are filtered out. FL-41 blocks blue and green. These colors are thought to be a problem to patients with light sensitivity.
5. Can FL-41 filter be added to any glasses? FL-41 filter is best absorbed by the regular (cr-39) plastic lens material. Glasses made of certain plastics have a reflective coating may be more difficult.
6. Where can I get FL-41 filter? Many optical shops can get FL-41 tint. OPI has the tint available. Be sure that the company you choose has tested the filter to see that it has the correct characteristics. If you have trouble you may call The Moran Eye Center in Salt Lake City, UT (801)587-3765 to discuss your needs; they have had years of experience with this tint..
Kathleen B. Digre, MD, FAHS, Director, Division of Headache and Neuro-ophthalmology, Professor Neurology, Ophthalmology, University of Utah, Moran Eye Center, Salt Lake City, UT.