Everyone is sensitive to light to some degree, but light sensitivity, or photophobia is an abnormal intolerance for light. Discomfort can be experienced from light sources such as sunlight and fluorescent or other artificial lights. It may cause the person with light sensitivity to squint or to have to close their eyes. It can cause pain and/or tears. In some cases, this may be accompanied by a headache.
The brighter the light, the greater the discomfort. Generally people with this condition are affected by bright lights, but in extreme cases any light can trigger the effect. The wavelength of the light (i.e. the color) may also be important. For example, blue light generally causes more trouble than other colors.
Large changes in light levels can cause this condition. For example, if you often spend time in darkened rooms, you will be less used to brighter lights and notice them more.
The exact area of the brain that causes light sensitivity is unknown. Light is carried in the visual pathways to the brain via the retina. The retina primarily contains cells that detect light and form and projects them onto the visual pathway through the optic nerve. The light sensitivity may be partially caused by the rods and cones not recovering efficiently.
The retina also contains some cells which are part of the melanopsin system. This system doesn’t appear to be involved in formed vision but it does sense light. Once these cells get turned on, these cells do not turn off.
Both types of cells in the retina may be involved in light sensitivity. These cells do connect with the trigeminal system located in the deep brain center – and this explains how bright lights can cause pain. The melanopsin system also explains why people who are blind, and thus have no formed vision, can still experience light sensitivity.
Diagnosis
If you are experiencing severe light sensitivity, you should consult a physician. Your doctor will perform a physical examination and also examine your eyes. Tell your doctor about the frequency and severity of your symptoms as this will help them to determine the cause.
Causes
Technically, photophobia is not an eye disease. Rather, it is a symptom of another condition. For example, it can be caused by severe headaches, migraines, virus-caused illnesses or blepharospasm (eye twitch). Other conditions which can cause it include uveitis, dry eyes, thinning of the retina, corneal abrasion and nervous system disorders such as meningitis, encephalitis and subarachnoid hemorrhage. It can also be a symptom of contact lens irritations, detached retina, refractive surgery and sunburn.
Photophobia may also be a symptom of thyroid conditions or diabetes.
Dry eye syndrome makes the cornea more sensitive to light. Studies have also shown that computer users tend to blink less as they are working on the computer for long periods of time. This as well can result in dry eyes.
People with light eye colors are more likely to experience this condition because they contain less of the pigment which protects the eyes from harsh lighting. Albinism is the lack of eye pigment and it can be accompanied with photophobia.
It can also be associated with total color deficiency (where only shades of gray are seen), mercury poisoning, keratitis, iritis, rabies, botulism and conjunctivitis.
Rare diseases like keratosis follicularis spinulosa decalvans (KFSD), which is a genetic disorder, can also cause photophobia.
Some medications can have light sensitivity as a side effect. For example, antibiotics such as doxycycline and tetracycline, diuretics such as furosemide, anti-malarial drugs such as quinine, antihistamines, blood pressure medications, digoxin, belladonna and photosensitizing drugs can have this effect. (See Drugs That Harm the Eyes for a list of medications that can affect your eyes.)
Prognosis
The prognosis varies depending on the underlying cause of the condition.
Treatment
The only way to substantially reduce light sensitivity is to address the underlying cause. In many cases once the triggers are removed, the light sensitivity disappears.
If the photophobia is a side effect of a medication, sometimes your doctor can discontinue or replace the medication.
Treating migraines and blepharospasm may be helpful, since they are the two most common causes of light sensitivity. Dry eyes can complicate chronic photophobia, so dry eye treatments such as artificial tears, gels and ointments can help.
Intermittent light sensitivity associated with migraines usually reduce with the use of migraine medications. Preventive migraine treatments can also help.
To alleviate the discomfort caused by photophobia, you should avoid direct sunlight and bright room lights, particularly fluorescent lights. If necessary, stay in a darkened room or wear sunglasses or glare control glasses. Some people find that tinted lenses help, in particular FL-41 tint, blue-blocking lenses, or red lenses.
Other Treatments
A study by Stringham and Hammond, published in the Journal of Food Science has shown that visual performance improves and light sensitivity (glare) decreases in subjects taking carotenoids (10 mg lutein and 2 mg zeaxanthin) per day.* See also recent studies for sensitivity to light.
Lutein is found in high quantities in green leafy vegetables such as spinach, kale and yellow carrots. Zeaxanthin is the pigment that gives paprika, corn and saffron (and some other plants) their characteristic color.
Fruits and vegetables (preferably organic) are a good way to obtain carotenoids. These can be taken in the form of a daily juice mixture. Learn more about juicing.
Other nutrients such as bilberry, vinpocetine, l-lysine, a number of vitamins and enzymes, and fish oil may help with photophobia and help preserve vision. These can be taken as supplements. See our recommendations for healthy vision for more information.
A preservative-free eyedrop can help lubricate your eyes if you have dry eyes.
If you are sensitive to the glare of headlights at night, you may need prescription glasses for night driving. See your eye doctor to determine if that would be helpful. Keeping your eyes focused more on the edge of the road, rather than on approaching headlights, may help you avoid the glare.
If you find that you have become very sensitive to light, it is important to visit a physician to determine the underlying cause of this condition. Sometimes it can a symptom of a serious condition.
* Stringham JM, Bovier ER, Wong JC, Hammond BR (2010). “The influence of dietary lutein and zeaxanthin on visual performance”. J. Food Sci. 75 (1): R24–9. doi:10.1111/j.1750-3841.2009.01447.x. PMID 20492192