Photophobia

Photophobia

[foh-tuh-foh-bee-uh]
Photophobia is a symptom of excessive sensitivity to light and the aversion to sunlight or well-lit places. In medical terms it is not fear, but an experience of discomfort or pain to the eyes due to light exposure.

Light sensitivity is usually due to too much light entering the eye, which causes over stimulation of the photoreceptors in the retina and subsequent excessive electric impulses to the optic nerve. This leads to a reflex aversion to light, and discomfort or pain. 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).

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.

Photophobia is also a behavior demonstrated by insects or other animals which seek to stay out of the light.

Causes

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

In mythology

In folklore and mythology, many creatures suffer from photophobia — or heliophobia, a specific fear of sunlight.

  • Some of the many forms of Norse trolls are said to either turn to stone or become trapped above ground when the sun rises.
  • C. S. Lewis wrote that the alchemist Paracelsus believed that gnomes explode when they go above ground: "if he thrust out his face ... [it] would break into splinters, bursting as a man would burst in interstellar space" — though in fact, humans exposed to the vacuum of space experience no such spectacular effect.
  • In English folklore, goblins are said to find light unbearable.
  • In Lithuanian and some other Eastern European folklore, the devil is said to go back to hell whenever the sun rises.

In fiction

See also

References

Lewis, C.S. Poems: C.S. Lewis. U.S.: Harvest/HBJ, 1964. ISBN 0-15-672248-8.

External links

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