Flash blindness

This article reviews direct and indirect (e.g., afterimage, flash blindness) light hazards from common incoherent light sources. For direct hazards specific to lasers and other specialized coherent sources, the reader is referred to organizations such as the Laser Institute of America and the International Electrotechnical Commission. 

Heat and light cause thermal injuries, such as flash bums, flame bums and retinal bums. Temporary depletion of photopigment from the retinal receptors causes flash blindness. The blast wave causes physical injuries, such as fractures, lacerations, visceral ruptures, pulmonary hemorrhage and edema. 

Temporary loss of vision. Bright light experience. No pain. External exam normal. Internal exam normal. Glare, dazzle, or flash-blindness. (Low dose laser.) None. Return to duty. 

FIGURE 1.3 Pilot wearing the flash-blindness goggles (in the "off" position). 

There is very little hazard from Class 2 lasers or even Class 3R pointers. However, you should know that there are no restrictions on the sale of laser pointers in the United States and more powerful laser pointers exceeding the MPE and having power in excess of 5 mW may be found as imports from other countries. The Food and Drug Administration (FDA) has issued a warning that laser pointers should not be considered toys and should not be used by children without supervision. Short exposure to these more powerful laser pointers can result in temporary flash blindness. 

Iodine reacts dangerously with numerous elements. Thus, with aluminium, magnesium or powdered zinc, the mixture with iodine in contact with a drop of water gives rise to a flash , which is extremely violent and blinding. In the very spectacular experiment involving ammonium nitrate and zinc described on p.208 and carried out with students, it is recommended to Incorporate a small quantity of iodine before throwing a few drops of water on the mixture. 

With compression moulding, to ensure dimensional consistency, it is necessary to allow the excess material to move away from the edge of the cavity so that the lands between the cavities can contact with minimum thickness of rubber (flash) between them. Spew grooves and channels are provided of sufficient dimensions to accommodate this excess, and also to allow the escape of air from the mould cavity. In some cases, where the shape is complex, it may be necessary to provide extra venting to allow air to escape from a blind area, where it is likely to be trapped. 

Blurred vision, diplopia, flashing lights, blindness, papilledema... 

It was well the blind eyes could not see the look of startled fear which flashed across Cecile s face. 

Flash Hide r or Muzzle Flash Suppressor (Dampfer, in Ger). A metallic cone and/or flat disks which ate attached to the muzzle of a gun to conceal the flash when the gun is fired and to prevent temporary blindness of the crew while firing... 

Dark and Dim Igniters. The usual pyrotechnic igniter compns, used in tracers, burn rapidly with a bright flash. In order not to blind a gunner nor to disclose the position of the gun to the enemy, it is desirable, that the igniter compound not produce visible light at the muzzle and that the tracing action start only at some specified distance from the gun. Ig-... 

The operators should be instructed not to look in the direction of the bombs when they are being detonated as the flash is very blinding... 

If a person has been totally blind from birth, he may reason about vision. He may come to some clever, partial understandings, but he will never really understand the beauty of a sunset. Until we have at least flashes of objective consciousness, we will never fully understand the nature of life. 

One out of five migrane sufferers experience this stage of visual disturbances There may be flashing lights, shimmering zig-zag lines, and luminous blind spots, as well as non-visual sensations like numbness and pins and needles in the hands... 

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