Most of us have experienced the sharp discomfort of coming out of the dark cinema to a bright, sunny afternoon. The light is blinding and it’s hard to understand how we normally tolerate such brightness. In most cases, the painful reaction is mercifully fleeting with no unpleasant side effects. For migraineurs, much lower levels of brightness can have far reaching consequences.

How Bright is Too Bright?

People who suffer from photophobia (including those with migraine) experience discomfort and pain at lower light levels than the rest. Research indicates that for those without migraine, light only becomes too bright when it reaches around 23,000 lux--equivalent to the light on a bright, cloudless sunny day.

For those with migraine, however, light levels between 500 and 1,000 lux (such as on an overcast, dull day) can be uncomfortable or pain-inducing.

What Causes Photophobia?

The exact causes aren’t known, although research provides some clues. Despite the word ‘phobia’ being part of the name, the condition has nothing to do with a fear of light, but indicates extreme sensitivity. Some people refer to the condition as ‘photosensitive’ but medically this means those whose skin is sensitive to light, not the eyes.

Certain medical conditions are associated with photophobia, including:

• Dry eyes
• Inflammatory conditions such as iritis
• Inherited degenerative conditions of the retina, like pigmentosa or cone dystrophy.
• Meningitis, subarachnoid hemorrhage or a pituitary tumor, or other disorders of the central nervous system.
• Psychiatric disorders such as depression

That doesn't mean a sensitivity to light is indicative of any of these conditions since there are other causes too.

The links between the trigeminal system and migraine headaches are well-established, and the first division of the trigeminal system is closely involved with light sensitivity. In one study it was found light stimulated the trigeminal system even in blind people, indicating light sensitivity may not necessarily be linked to the visual system.

A separate study amongst blind migraineurs found those with some ability to detect light had worse migraine pain when exposed to bright light, whereas those with no light detection experienced no worsening of their symptoms. Some medical professionals believe this indicates a relationship between light sensitivity and the optic nerve. Other studies show people with light-colored eyes may be more sensitive to light than those with dark eyes.

Photophobia and Migraine

Bright light triggers migraine or makes existing headaches worse in 80% of sufferers, and 98% say they can predict headache onset by light levels. Photophobia is so common among migraine sufferers it’s an important part of diagnostic criteria set out by the International Headache Society. Just being sensitive to light can indicate an underlying migraine condition.

All types of light can trigger an attack, not just the steady light of bright day. Common types include:

• Flickering lights
• Glaring light (such a sun reflected on a wet road)
• Fluorescent lights used at home
• Low resolution computer screens
• TV screens
• Patterns of light, or even high-contrast checkered patterns or stripes that are not illuminated.

Countering Photophobia

As yet, science hasn’t found a cure for photophobia although there are various ways of minimizing the effects both at home and work or when out and about:

Wearing Dark Glasses or Filtering Lenses

Studies done at King’s College Hospital in London and the European Institute of Health and Medical Sciences found migraineurs are especially sensitive to the red and blue light at either end of the spectrum. The greens and yellows in the middle are less problematical. Filtering out the reds and blues through wearing specially developed migraine lenses can have a beneficial effect. Other studies found rose-tinted glasses helped children with migraine.

Standard, polarizing sunglasses can also help filter out the glare of bright sunlight in everyday situations.

Computer Screens

Hard to avoid these days, here are a few tips to help those who work with computers all day:

• Maintain screens to minimize flicker, and have static rather than flashing cursors.
• Place screens away from windows to minimize glare
• Turn down the brightness of the screen. Most of us have got used to working with our screens too bright.
• Look away from the screen at regular intervals to give eyes a rest.

CFL Light Bulbs

In America, CFLs save 2,000 times their weight in greenhouse gasses, so are an important part of energy efficiency and environmental care. They’re not so friendly to migraineurs, however, as these compact fluorescents can trigger migraines just as ordinary fluorescent lamps can. While much of the evidence is anecdotal, if your migraines become worse in indoor situations it could be due to the type of lighting.

If photophobia is one of your migraine triggers, you may find it impossible to stay totally in control. However, understanding your environment and taking small steps to control what you can, could help reduce migraine frequency or severity.