photophobia

Photophobia (from Greek φῶς - phōs, "light"^[1] and φόβος - phobos, "fear"^[2]) is a symptom of abnormal intolerance to visual perception of light.^[3] As a medical symptom photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical photosensitivity of the eyes,^[4] though the term is sometimes additionally applied to abnormal or irrational fear of light such as heliophobia.^[5]

Causes

Patients may develop photophobia as a result of several different medical conditions, related to the eye or the nervous system.

Photophobia can be caused by an increased response to light starting at any step in the visual system, such as:

• Too much light entering the eye. Too much light can enter the eye if it is damaged, such as with corneal abrasion and retinal damage, or if a pupil(s) is unable to normally constrict (seen with damage to the oculomotor nerve).
• Overstimulation of the photoreceptors in the retina
• Excessive electric impulses to the optic nerve
• Excessive response in the central nervous system

Common causes of photophobia include migraine headaches, cataracts, or severe ophthalmologic diseases such as uveitis or corneal abrasion.^[6] A more extensive list follows:

Eye-related

Causes of photophobia relating directly to the eye itself include:

• Achromatopsia^[7]
• Aniridia^[8]
• Anticholinergic drugs may cause photophobia by paralyzing the iris sphincter muscle.^{[citation needed]}
• Aphakia^[9] (absence of the lens of the eye)
• Buphthalmos^[8] (abnormally narrow angle between the cornea and iris)
• Cataracts^[8]
• Cone dystrophy^[8]
• Congenital abnormalities of the eye^[8]
• Viral conjunctivitis ("pink eye")^[10]
• Corneal abrasion^[8]
• Corneal dystrophy^[8]
• Corneal ulcer^[11]
• Disruption of the corneal epithelium, such as that caused by a corneal foreign body or keratitis ^[8]
• Ectopia lentis^[8]
• Endophthalmitis^[8]
• Eye trauma caused by disease, injury, or infection such as chalazion, episcleritis, glaucoma,^[8] keratoconus, or optic nerve hypoplasia
• Hydrophthalmos, or congenital glaucoma^[8]
• Iritis^[8]
• Optic neuritis^[8]
• Pigment dispersion syndrome^{[citation needed]}
• Pupillary dilation (naturally or chemically induced)^[9]
• Retinal detachment
• Scarring of the cornea or sclera ^[8]
• Uveitis^[8]

Nervous-system-related

Neurological causes for photophobia include:

• Autism spectrum disorders ^[12]
• Chiari malformation
• Dyslexia^[13]
• Encephalitis^[8] including Myalgic encephalomyelitis aka Chronic fatigue syndrome^[14]
• Meningitis^[8]
• Subarachnoid haemorrhage^[15]
• Tumor of the posterior cranial fossa^[8]

Other causes

• Ankylosing spondylitis^[16] - Causes Uveitis as an extra-articular feature.
• Albinism^{[17] [18]}
• Ariboflavinosis^[19]
• Benzodiazepines (long term use of or withdrawal from benzodiazepines)^[20][21]
• Chemotherapy^[8]
• Chikungunya^[22]
• Cystinosis^[8]
• Ehlers-Danlos syndrome^[23]
• Hangover^[24]
• Influenza^[25]
• Infectious Mononucleosis^[26]
• Magnesium deficiency^[27]
• Mercury poisoning^[28]
• Migraine^[29]
• Rabies^[30]
• Tyrosinemia type II, also known as "Richner-Hanhart syndrome"^[8]

Treatment

The best treatment for light sensitivity is to address the underlying cause. Once the triggering factor is treated, photophobia disappears in many but not all cases.^[31]

Patients with photophobia will avert their eyes from direct light (sunlight and room lights), or may seek the shelter of a dark room or wear sunglasses.

A study by Stringham and Hammond, published in the Jan-Feb issue of Journal of Food Science, discusses the improvement in visual performance and decrease in light senitivity (glare) in subjects taking 10 mg Lutein and 2 mg Zeaxanthin per day.^[32]

See also

• Light sensitivity
• Photic sneeze reflex, a medical condition by which people exposed to bright light sneeze
• Photosensitivity in humans

References

External links

• AllAboutVision.com page on photophobia
• WrongDiagnosis.com page on photophobia