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Photophobia is a symptom of abnormal intolerance to visual perception of light.[1] 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,[2] though the term is sometimes additionally applied to abnormal or irrational fear of light such as heliophobia.[3] The term photophobia comes from the Greek φῶς (phōs), meaning "light", and φόβος (phóbos), meaning "fear". Photophobia is a common symptom of visual snow.[4][5]

Photophobia
Specialty Neurology

Contents

CausesEdit

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(s) 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 can't 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
  • Elevated trigeminal nerve tone (as it is sensory nerve to eye, elevated tone makes it over reactive). Elevated trigeminal tone causes elevated substance P which causes hypersensitivity. Often due to jaw misalignment.[6]

Common causes of photophobia include migraine headaches, TMJ, cataracts, Sjogren's Syndrome, Mild Traumatic Brain Injury (MTBI), or severe ophthalmologic diseases such as uveitis or corneal abrasion.[7] A more extensive list follows:

Eye-relatedEdit

Causes of photophobia relating directly to the eye itself include:

Nervous-system-relatedEdit

Neurological causes for photophobia include:

Other causesEdit

TreatmentEdit

The best treatment for light sensitivity is to address the underlying cause, whether it be an eye, nervous system or other cause. Notwithstanding recent progress in understanding light sensitivity of the eye, much more research is needed to better understand and treat photophobia, especially where it relates to migraine or other nervous system disorders. Genetic research into photophobia-related disorders is also needed. If the triggering factor or underlying cause can be identified and treated, photophobia may disappear.[34]

Artificial LightEdit

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. Althernatively, they may wear dark sunglasses, sunglasses designed to filter peripheral light, and/or wide-brimmed sun hat or a 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.[35][36]

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 seizure 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.[37]

EffectsEdit

Severe or chronic photophobia, such as in migraine or seizure disorder, may result in a person not feeling well with eye ache, headache and/or neck ache. These symptoms may persist for days even after the person is no longer exposed to the offensive light source. Further, once the eyes have become sensitized to the offensive light source (which can occur even in short duration exposures), they may become even more photosensitive with extreme pain occurring upon exposure to light.

Chronic photophobia may also adversly impact a person's ability to interact in social settings and the work place. Bright overhead lighting may make shopping a very painful experience for example, or render the patient dysfunctional in the work place. Office lighting intended to allow employees to get their work done may prevent one with photophobia from getting the job done and lead to such person getting fired. The physical and psychological effects of being in constant pain and overwhelmed with bright light that co-workers cannot perceive also stacks the deck heavily against one with photophobia having a successful career or even making a living. As such, photophobia can be a cruel, yet invisible disorder. Cultural factors associating darkness with evil, lack of interest or training among general practitioners or specialists, and a historical lack of medical research interest/support in the area have also tended to stigmatize and isolate photophobia patients, leaving them vulnerable to workplace discrimination or unfair treatment/job loss.

DisabilityEdit

Photophobia may preclude or limit a person from working in places where offensive lighting is virtually ubiquitous (e.g., big box stores, airports, libraries, hospitals, warehouses, offices, workshops, classrooms, supermarkets and storage spaces), unless the person is able to obtain a reasonable accommodation (which may be required to be provided by an employer under the Americans with Disabilities Act). Some people with photophobia may be better able to work at night, or be more easily accommodated in the work place 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 lamps.

Environmental TriggersEdit

The technology for low cost lighting has, in many cases, outpaced the ability of regulatory agencies to understand and appropriately regulate it. In many areas, such lighting has been installed on the basis of saving energy alone and is virtually unregulated. As a result, possible health impacts on sensitive receptors (human and animal), such as migraine and circadian rhythm, may be inadequately evaluated in project reviews. Compared to other environmental media such as air and water, scientific study of the environmental and health affects of artificial lighting is also virtually non-existent.

Given that the technology is relatively new, communities considering installing LED lighting based on energy savings alone and rosy projections by the lighting industry may find that purported savings are more than offset in the long run by unforeseen costs, such as bulb replacement, retro-fitting with shielding to reduce glare, increasing pole height, and those transferred to sensitive receptors who incur medical expenses related to the new lighting (e.g., migraine). Also worth considering is the potential for legal liability, given recent damage awards from legal actions based on common law nuisance, light trespass, light pollution, improper notice, and other grounds.

In 2012, for example, a group of residents calling themselves Turn Down The Lights filed suit against the City of Monterey, California, claiming new LED streetlight bulbs installed were significantly brighter than the ones they replaced, and that the city had failed to conduct an environmental review before making the change. In a December 20, 2016 ruling, Monterey County Superior Court Judge Lydia Villarreal found that the city violated both the California Environmental Quality Act (CEQA) and the Brown Act when it started to install energy-efficient LED streetlights in 2009.

See alsoEdit

ReferencesEdit

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