Photophobia

Photophobia is a medical symptom of abnormal intolerance to visual perception of light.<ref>thefreedictionary.com/photophobia citing:

• Dorland's Medical Dictionary for Health Consumers. 2007
• The American Heritage Medical Dictionary Copyright 2007
• Miller-Keane Encyclopedia & Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. 2003
• Millodot: Dictionary of Optometry and Visual Science, 7th edition. 2009</ref> 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 sensitivity of the eyes,<ref>thefreedictionary.com/photophobia citing:
• Gale Encyclopedia of Medicine. Copyright 2008
• Mosby's Medical Dictionary, 8th edition. 2009
• McGraw-Hill Concise Dictionary of Modern Medicine. 2002</ref> though the term is sometimes additionally applied to abnormal or irrational fear of light, such as heliophobia.<ref>thefreedictionary.com/photophobia citing:
• The American Heritage Medical Dictionary Copyright 2007
• Millodot: Dictionary of Optometry and Visual Science, 7th edition. 2009</ref> The term photophobia comes Template:Ety.<ref>φῶς, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus</ref><ref>φόβος, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus</ref>

Causes

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

Photophobia may manifest itself in 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 its pupil is unable to normally constrict (seen with damage to the oculomotor nerve).
• Due to albinism, the lack of pigment in the colored part of the eyes (irises) makes them somewhat translucent. This means that the irises cannot completely block light from entering the eye.
• 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, TMJ, cataracts, Sjögren syndrome, mild traumatic brain injury (MTBI), or severe eye diseases such as uveitis or corneal abrasion.<ref>Template:Cite journal</ref> A more extensive list follows:

Eye-related

Causes of photophobia relating directly to the eye itself include: Template:Div col

• Achromatopsia<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Aniridia<ref name="taylor">Template:Cite book</ref>
• Anticholinergic drugs may cause photophobia by paralyzing the iris sphincter muscleTemplate:Citation needed
• Aphakia<ref name="tsbvi">{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Blepharitis<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Buphthalmos<ref name="taylor" />
• Cataracts<ref name="taylor" />
• ColobomaTemplate:Citation Needed
• Cone dystrophy<ref name="taylor" />
• Congenital abnormalities of the eye<ref name="taylor" />
• Viral conjunctivitis<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Corneal abrasion<ref name="taylor" />
• Corneal dystrophy<ref name="taylor" />
• Corneal ulcer<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Disruption of the corneal epithelium, such as that caused by a corneal foreign body or keratitis<ref name="taylor" />
• Ectopia lentis<ref name="taylor" />
• Endophthalmitis<ref name="taylor" />
• Eye trauma caused by disease, injury, or infection such as chalazion, episcleritis, keratoconus, or optic nerve hypoplasia<ref name="taylor" />
• Hydrophthalmos, or congenital glaucoma<ref name="taylor" />
• Iritis<ref name="taylor" />
• Isotretinoin has been associated with photophobia<ref>Template:Cite journal</ref>
• Optic neuritis<ref name="taylor" />
• Pigment dispersion syndrome Template:Citation needed
• Pupillary dilation (naturally or chemically induced)<ref name="tsbvi" />
• Retinal detachment
• Scarring of the cornea or sclera<ref name="taylor" />
• Uveitis<ref name="taylor" />

Nervous-system-related

Neurological causes for photophobia include: Template:Div col

• Autism spectrum disorder<ref>Template:Cite journal</ref>
• Chiari malformation
• Dyslexia<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Encephalitis,<ref name="taylor" /> including myalgic encephalomyelitis<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Meningitis<ref name="taylor"/>
• Trigeminal disturbance causes central sensitization (hence, multiple other associated hypersensitivities). Causes can be bad bite, infected tooth, etc.<ref>Template:Cite journal</ref>
• Progressive supranuclear palsy, where photophobia can sometimes precede the clinical diagnosis by years<ref>Template:Cite journal</ref>
• Subarachnoid haemorrhage<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Tumor of the posterior cranial fossa<ref name="taylor" />
• Visual snow along with many symptomsTemplate:Citation neededTemplate:Div end

Other causes

• Ankylosing spondylitis<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Albinism<ref>Template:Cite encyclopedia</ref>
• Ariboflavinosis<ref>Template:Cite book</ref>
• Benzodiazepines<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
• Chemotherapy<ref name="taylor" />
• Chikungunya<ref>Template:Cite journal</ref>
• Cystinosis<ref name="taylor" />
• Drug withdrawal
• Ehlers–Danlos syndrome
• Infectious mononucleosis<ref>Template:Cite journal</ref>
• Influenza<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Magnesium deficiency<ref name="durlach">Template:Cite book</ref>
• Mercury poisoning<ref>Template:Cite journal</ref>
• Migraine<ref>Template:Cite journal</ref>
• Mustard gas exposure
• Rabies<ref>Template:Cite journal</ref>
• Tyrosinemia type II<ref name="taylor" />
• Superior canal dehiscence syndrome<ref>SCDS Society</ref>Template:Nonspecific

Treatment

Treatment for light sensitivity addresses the underlying cause, whether it be an eye, nervous system or other cause. If the triggering factor or underlying cause can be identified and treated, photophobia may disappear. Tinted glasses are sometimes used.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Artificial light

People with photophobia may feel eye pain from even moderate levels of artificial light and avert their eyes from artificial light sources. Ambient levels of artificial light may also be intolerable to persons afflicted with photophobia such that they dim or remove the light source, or go into a dimmer lit room, such a one lit by refraction of light from outside the room. Alternatively, they may wear dark sunglasses, sunglasses designed to filter peripheral light, precision tinted glasses, and/or wide-brimmed sun hats or baseball caps. Some types of photophobia may be helped with the use of precision tinted lenses which block the green-to-blue end of the light spectrum without blurring or impeding vision.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Other strategies for relieving photophobia include the use of tinted contact lenses and/or the use of prescription eye drops that constrict the pupil, thus reducing the amount of light entering the eye. Such strategies may be limited by the amount of light needed for proper vision under given conditions, however. Dilating drops may also help relieve eye pain from muscle spasms or seizures triggered by lighting/migraine, allowing a person to "ride out the migraine" in a dark or dim room. A paper by Stringham and Hammond, published in the Journal of Food Science, reviews studies of effects of consuming lutein and zeaxanthin on visual performance, and notes a decrease in sensitivity to glare.<ref>Template:Cite journal</ref>

Disability

Photophobia may preclude or limit a person from working in places where lighting is used, unless the person is able to obtain a reasonable accommodation like being allowed to wear tinted glasses. Some people with photophobia may thereby be better able to work at night or be more easily accommodated in the workplace at night.

Outdoor night lighting may be equally offensive for persons with photophobia, however, given the wide variety of bright lighting used for illuminating residential, commercial and industrial areas, such as LED (light-emitting diode) lamps.<ref>Guide to Photophobia/Light Sensitivity, axonoptics.com. Retrieved January 11, 2019.</ref><ref>Lightmare, lightmare.org. Retrieved January 11, 2019.</ref>

The increasing popularity of "overpoweringly intense" LED headlights being used on "pickups and S.U.V.s" has prompted more frequent reports of photophobia among motorists, cyclists, and pedestrians.<ref>"Blinded by Brighter Headlights? It's Not Your Imagination.", The New York Times, June 5, 2021. Retrieved June 11, 2021.</ref>

See also

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