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Ballistic sunglasses or prescription eyeglasses must meet the same requirements. In brief, the U.S. military standard requires that ballistic eyewear must be able to withstand up to a 3.8 mm (.15 caliber) projectile at 195 m/s (640 ft/s)) for spectacles and 5.6 mm (.22 caliber) projectile at 168–171 m/s (550–560 ft/s) for goggles.
Safety glasses or spectacles, although often used as a catch-all term for all types of eye protection, specifically revers to protective equipment that closely resembles common eye wear. To meet most national standards, spectacles must include side shields to reduce the ability of debris to get behind the lenses from the side.
Some styles can accommodate prescription lenses. Several types of goggles are available because they are optimized for certain purposes, such as regular use, use in vehicles, or use with night vision goggles. Some fit over regular eyeglasses, some can accommodate prescription lenses, and others are designed for those who do not wear eyeglasses. [4]
Inadequate dark lenses are even more harmful than inadequate light lenses (or wearing no sunglasses at all) because they provoke the pupil to open wider. As a result, more unfiltered radiation enters the eye. Depending on the manufacturing technology, sufficiently protective lenses can block much or little light, resulting in dark or light lenses.
Typical sunglasses lenses are tinted for protection against bright light or polarized to remove glare; photochromic glasses are clear or lightly tinted in dark or indoor conditions, but turn into sunglasses when they come into contact with ultraviolet light. Most over-the-counter sunglasses do not have corrective power in the lenses; however ...
GI glasses are eyeglasses issued by the American military to its service members. Dysphemisms for them include the most common " birth control glasses " ( BCGs ) and other variants. At one time, they were officially designated as regulation prescription glasses ( RPGs ).
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