04 Jul Light and Headache Disorders: Understanding Light Triggers and Photophobia
“Wearing sunglasses indoors is increasing your sensitivity to light.” My wife and I were floored when her headache specialist made this statement. Chronic migraine had made her so sensitive to light that she had to wear sunglasses indoors. During an attack, photophobia increased her misery. Sunlight, light from computer monitors and TVs, and fluorescent lights triggered even more attacks.
When my wife protested that sunglasses were her only way to quell the pain, her physician’s response excited us both. Research had found that a special tint for glasses resulted in 74% fewer migraine attacks per month! When we did more reading at home, we found that the study the specialist mentioned, was part of more than 20 years of research on light sensitivity. The problem was finding glasses that blocked enough light for the tint to be effective.
I had watched my wife suffer for many years, and while I could relate because of my own episodic migraine, I often felt helpless in her struggle. This time I saw a way to help. My background is in new product development, so I put those skills to work and made exactly the glasses we envisioned for her. My wife got so much relief that we made a few more pairs to help other people we know who experience migraine. Eventually, we established a company that manufactured specialized eyewear.
Although we started the company because of our personal migraine experience, we quickly learned that photophobia is a symptom of more than 40 health conditions. And, it is not the only headache disorder, cluster headache, new daily persistent headache (NDPH). Concussion or traumatic brain injury (TBI), and trigeminal autonomic cephalalgias (including hemicranias continua and SUNCT) can also photophobia.
What is Photophobia?
Do lights seem too bright to you? Does light make your head pain even worse when you have a headache or are in a migraine attack? Do your eyes ever hurt or feel uncomfortable due to light? Do you have an aversion to light whether you have pain or not? If you answered “yes” to any of these questions, you most likely have photophobia.
The word, photophobia is derived from two Greek words: photo- “light” and phobia “fear or dread of”—hence, “fear of light.” However, in medical terms, it is not a morbid fear or phobia, but rather a symptom, common in migraine, as well as ophthalmic and other neurological disorders. The patient with photophobia experiences discomfort or pain in the eyes due to exposure to light (sunlight, fluorescent lights, TV or computer screens, or the glare from snow).
Does the Kind of Light Matter?
The brighter the light, the more discomfort, pain, or aversion you probably feel. The wavelength or color of light also plays a role. Blue-green light causes more photophobia than other colors. Between computer and device screens, fluorescent and LED light bulbs, and even sunlight, our lives are awash with this light.
What Causes Photophobia?
Photophobia is a neurological issue that involves communication between receptors in the eye and the brain. The part of the eye that transmits photophobia to the brain is different than the part that transmits vision. In fact, a person can be completely blind and still be sensitive to light.
What’s the Science of Photophobia?
Photophobia has been recorded in medical writings since the 1930s but has not been well understood scientifically until recent breakthrough discoveries. A team led by researchers at Harvard Medical School published a study in 2010 that found a pathway from the eyes to areas of the brain that are active during a migraine attack. Light can worsen pain during an attack by activating nerve cells in these areas of the brain.
Researchers also found a special kind of cell in the eye—intrinsically photosensitive retinal ganglion cells. These cells are distinct from the rods and cones in the eye that enable us to see. The cells are more sensitive to some wavelengths of light than others, with particular sensitivity to blue-green light.
Which Headache Disorders Are Associated with Photophobia?
Photophobia is so common in migraine that it is one of the symptoms that health care practitioners rely on when making a diagnosis. Between 80% and 90% of people living with migraine and headache disorders will experience photophobia during migraine attacks and even can find low levels of light to be glaring or painful. Between attacks, many people with migraine are more sensitive to light than those without migraine.
Light and other visual stimuli also can trigger migraine attacks: for example, flickering or pulsing lights, repetitive patterns, glare, bright lights, computer screens, TV, and movies. Fluorescent light contains invisible pulsing, which is likely why so many report it as a migraine trigger.
Tension-type headache can also cause photophobia during and between headaches. However, individuals with tension-type headache are generally less sensitive to light than those with migraine.
During a series, cluster headache can cause light sensitivity both during and between attacks. Between cluster series, those with cluster headache have the same levels of photophobia as those without a headache disorder.
New Daily Persistent Headache (NDPH)
Estimates of photophobia in NDPH range from 46% to 66%, depending on the study that you are reading. A 2002 study found 48% of people with NDPH found pain relief by going into a dark room.
Traumatic Brain Injuries (Concussions)
Photophobia is the most common visual problem reported by people with traumatic brain injuries (TBI). About 60% of military veterans with TBI report severe light sensitivity.
TBI can also cause a person to feel ill when exposed to fluorescent lighting, according to the International Brain Injury Association. Fluorescent light-induced symptoms can include headache, fatigue, dizziness, nausea, eye strain, eye fatigue, and increased sensitivity to visual input.
Hemicrania Continua, SUNCT, and Other Trigeminal Autonomic Cephalalgias
Although photophobia is hemicrania continua, SUNCT (short-lasting unilateral neuralgiform headache with conjunctival injection and tearing), and other trigeminal autonomic cephalalgias have not been studied extensively, photophobia is a known symptom of the headache disorders in this group.
What Types of Light are Most Problematic?
Any source of light can cause photophobia. Researchers have found that blue-green light can be particularly problematic because of the innate sensitivity of the pain-sensing cells in the eye. Blue-green light is everywhere, from artificial lighting like compact fluorescents, device and computer screens, and even sunshine, in studies comparing tints.
The tint that migraine glasses, such as TheraSpecs, use called F-41, filters those wavelengths thus reducing migraine attacks and providing the most relief for photophobia.
What’s the Treatment for Photophobia and How Does It Work?
No medications target photophobia specifically, but finding an effective treatment for your headache disorder could also reduce your sensitivity to light. Research has found eyewear with precision-tinted FL-41 lenses is the most reliable—and the only side-effect-free—way to treat photophobia. What Does the Research Say about FL-41?
When worn regularly, precision tinted FL-41 lenses can reduce the frequency of migraine attacks by filtering the light most likely to be a trigger. In a clinical study of the tint, participants experienced 74% fewer migraine attacks per month. Because FL-41 filters the wavelengths that cause the most pain responses for individuals with photophobia, the tinted glasses can provide relief no matter the reason why a person is sensitive to light.
How Do FL-41 Lenses Work?
As mentioned, some wavelengths of light are more likely to activate the eye and brain, causing pain and eyestrain. Furthermore, fluorescent lights pulse very rapidly. Although that rate is too fast to see consciously, the brain is still receiving the pulsing signals from the eye. This pulsing can trigger headaches, eyestrain, migraine attacks, and other issues. By filtering the wavelengths that contain most of this pulsing and those that cause the most pain and eyestrain, precision-tinted FL-41 lenses protect the brain from both.
Why Not Just Wear Sunglasses?
When you wear sunglasses indoors, your eyes adapt to being in the dark, which makes light appear even brighter than it is. This phenomenon, called chronic dark adaptation, is why my wife’s headache specialist advised us that her sunglasses were increasing her sensitivity to light. A similar situation would be leaving a movie theater on a sunny July day—your eyes adjust to being in the dark, so light looks even brighter than before you went into the theater. While most people’s eyes readjust to sunlight soon aver leaving a movie, those with chronic dark adaptation have extra-heightened light sensitivity at all times.
What to Look for in FL-41 Eyewear
Be sure your lenses are tinted correctly
Some optical shops can order the FL-41 tint, but applying it correctly requires practice and expertise. Lenses should be regularly checked by using a spectrophotometer to verify that the lenses are filtering the correct wavelengths of light.
Find the most therapeutic frames
Most tinted glasses focus on blocking the light directly in front of you, but the light that comes in the top or sides of your glasses or a glare from behind reflecting off your lenses can cause just as many problems. For the best protection, it is vital that your glasses provide sufficient isolation. Large or wraparound lenses are easy features to locate, but any pair that fits your face well could provide the same benefit.
Because my wife and I live with migraine, we created our glasses to respond to the unique needs of people with headache disorders. For example, we design our frames to be more highly protective than similarly style eyewear. Lightweight, flexible, and adjustable materials minimize extra weight or squeezing that can make pain even worse.
I have seen firsthand how photophobia and headache disorders can wreak havoc on a person’s life. It is my sincerest hope that those with photophobia and headache find relief. Tinted eyewear is one option for relief.
Watch Heads UP for more information on photophobia:
Digre KB, Breannan KC. Shedding light on photophobia. J Neuroophthalmol 2012; 32:68-81.