Eye Glasses in History Submitted by Abdul Nasser Kaadan, md, Phd ayman Foad Bankasly Contents



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Safety

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Figure 57: Safety glasses.

Figure 58: Safety glasses.
afety glasses are usually made with shatter-resistant plastic lenses to protect the eye from flying debris. Although safety lenses may be constructed from a variety of materials of various impact resistance, certain standards suggest that they maintain a minimum 1 millimeter thickness at the thinnest point, regardless of material. Safety glasses can vary in the level of protection they provide. For example, those used in medicine may be expected to protect against blood splatter while safety glasses in a factory might have stronger lenses and a stronger frame with additional shields at the temples to protect from sawdust, flying wood, or metal. The lenses of safety glasses can also be shaped for correction.

Safety glasses with side shields



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Figure 59: Safety glasses with side shields.
he American National Standards Institute has established standard ANSI Z87.1 for safety glasses in the United States, and similar standards have been established elsewhere.

OSHA provides guidance on the type of safety eyewear that should be used for a particular application.

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Figure 60: Safety glasses with side shields.


ome safety glasses are designed to fit over corrective glasses or sunglasses. They may provide less eye protection than goggles or other forms of eye protection, but their light weight increases the likelihood that they will actually be used. Modern safety glasses tend to be given a more stylish design in order to encourage their use. Corrective glasses with plastic lenses can be used in place of safety glasses in many environments; this is one advantage that they have over contact lenses.

Figure 61: Plastic lenses. Figure 62: Plastic lenses



Figure 63: Colored Plastic lenses



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Figure 64: Safety glasses for welding.
here are also safety glasses for welding, which are styled like wraparound sunglasses, but with much darker lenses, for use in welding where a full sized welding helmet is inconvenient or uncomfortable. These are often called "flash goggles", because they provide protection from welding flash.

Worker safety eyewear is available in various lens colors and/or with coatings to protect or enable eyesight in different lighting conditions, particularly when outdoors.



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Figure 65: Safety glasses for welding. P 23.

Figure 66: Safety glasses for welding. P 23.
ylon frames are usually used for protection eyewear for sports because of their lightweight and flexible properties. They are able to bend

slightly and return to their original shape instead of breaking when pressure is applied to them. Nylon frames can become very brittle with age and they can be difficult to adjust.

Safety lenses are usually made of

polycarbonate.[34] Polycarbonate and Trivex

lenses are the lightest and most shatter-resistant, making them the best for impact protection,[43] though polycarbonate offers poor optics due to high dispersion, having a low Abbe number of 31. Safety glasses are also available in prescription form for those persons who need corrective lenses.[35] Depending on the particular area in which the individuals work, they may be required to wear side protectors additionally to safety eyeglasses.

In order to comply with the ANSI Z87.1 requirements, safety eyeglasses must pass the high velocity and high mass tests. Also, the lenses of protective goggles, faceshield windows and welding filters cannot be thinner than 3 mm excepting the high impact lenses which are meant to be installed in prescription frames which cannot be thinner than 2 mm.


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