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Did You Know?
According to a survey conducted between 1966-1999 by the Federal Aviation Administration (FAA), helicopter pilots are more susceptible to flash blindness (caused by laser illumination) due to factors like relatively slower movement and low flight altitude of the helicopter.
Flash blindness is the most common type of temporary blindness that lasts for approximately 2 minutes during the day and a little longer than 3 minutes at night, after exposure to light of very high intensity. Why does flash blindness last longer at night? The pupils dilate at night to acclimatize to the dark. So, when there is a sudden flash of light, the retina receives more light, and gets a sudden jolt, causing temporary blindness, which lasts longer than during the day when the pupils are not dilated as much. The recovery time of this type of blindness is very low, depending on the intensity of the light, and the sensitivity of the retina and optical nerve. You tend to experience seeing bright spots during the time that your vision is impaired. Given below in this Buzzle write-up are the causes and potential risks of flash blindness.

Causes

The retina of the human eye is structured in layers. The layer that is just on the outer side of the neurosensory retina is called the retinal pigment. When the retinal pigment gets bleached, or oversaturated, one experiences a case of flash blindness. There are many reasons as to why the retinal pigment gets bleached. Sudden exposure to bright light causes the photoreceptors (rods and cones) in the eyes to go into a slight shock, causing temporary blindness. The factors that can cause flash blindness are:
  • Nuclear detonations
  • Solar eclipses
  • Photographer's flash
  • Sun lamp used in tanning salons
  • Closely struck lightning
  • Direct sunlight
  • Welding torch
  • Halogen lamp
  • Reflection of sunlight in water and off snow
  • Vehicular headlights at night
  • Momentary exposure to laser pointers

Potential Risks

Even though this blindness is temporary and only lasts for a couple of hours, there are risks associated with it that should be taken into consideration. Flash blindness is usually noticed in sportspersons, welders, affects those who are in the aviation industry, and those who use laser pointers irresponsibly.
  • If one is a pilot and experiences flash blindness due to being in proximity to lightning, it could affect the landing or taking off procedure of the plane due to his temporary loss of sight.
  • For sportspersons, camera flashes are the main cause of their flash blindness. They may get distracted and feel disoriented just after a camera flash goes off in the middle of their game.
  • Welders are at a risk of developing a condition called "arc eye" due to prolonged exposure to the high-intensity light used in their profession.

Precautions to be Taken
  • Spectators at sporting events are advised not to use flash so as to avoid distracting the players.
  • Those in the aviation industry are provided with helmets bearing visors that protect the eyes from light of high intensity.
  • While skiing, the gear provided has protective glasses to avoid getting exposed to the reflecting sunlight.
  • Civilians who usually drive at night are advised to drive on low beam instead of high beam.
  • During the occurrence of a solar eclipse, people are advised to stay indoors and not look up directly (without wearing appropriate protective eye gear) at the Sun.

In most cases, flash blindness is temporary, but there are some that are permanent due to acute scaring of the optical nerve and retina. Care must be taken to avoid exposure to light of very high intensity, as it may have damaging effects to the eyes.

If the intensity of the light entering through the pupil is too high, there are chances of a corneal flash burn. If symptoms like mild to severe pain, blurry vision, eye pricking, bloodshot eyes, light sensitivity, and excessive tearing are experienced, one must consult an ophthalmologist. The doctor may prescribe topical medication, over-the-counter ointments, or eye drops for this condition.

Disclaimer: This article is for informative purposes only and should not be substituted for the advice of a medical professional.