WHAT ARE SAFETY GLASSES?
EXPLANATION OF SAFETY GLASSES (FOR THE UNITED STATES)

The following description below is provided by www.allaboutvision.com/safety/safety-glasses.htm. and pertains to the US Standard for Safety Glasses.

WHAT ARE SAFETY GLASSES

What are Safety Glasses and How Do Safety Glasses and Goggles Differ From Regular Eyeglasses?

Safety eyewear must conform to a higher standard of impact resistance than regular eyeglasses, which optical professionals sometimes call “dress eyewear.” This higher standard applies to both the lenses and the frames of safety glasses and goggles.

Safety glasses may have prescription lenses or non-prescription (also called “plano”) lenses. Regardless of their size or the durability of the frame and lenses, regular prescription eyeglasses do not qualify as safety glasses unless they meet specific criteria.

In the United States, the federal government establishes safety guidelines for workplaces, to decrease the risk of on-the-job injuries. The Occupational Safety and Health Administration (OSHA) within the U.S. Department of Labor oversees safety practices in the workplace and in educational settings.

OSHA has adopted safety eyewear standards established by the American National Standards Institute (ANSI), a private, non-profit organization that creates quality and safety standards for a wide variety of products.

The ANSI standard applying to eye safety includes several types of eye protection devices, including eyeglasses (both prescription and non-prescription), goggles, face shields, welding helmets and full-face respirators.

ANSI Standards for Safety Eyewear

Updated ANSI safety eyewear standards include the following key features:

  • For the basic impact tests, lenses are tested separately (not mounted in a frame). For the high impact classification, the frame and lenses are tested together as a unit.
  • Non-prescription lenses used for high impact testing are considered to be structurally weaker than prescription lenses made of the same material; the prescription lenses are generally thicker.
  • Thinner prescription safety lenses are now allowed, if they meet the high impact testing requirements. (Previously, all prescription safety lenses had to have a minimum thickness of 3 mm, making them significantly thicker and heavier than regular eyeglass lenses.)

     

  • Safety lenses now have two classifications of performance: basic impact and high impact.

     

  • The “drop ball” test determines the basic impact safety classification for lenses. In this test, a one-inch diameter steel ball is dropped onto the lens from a height of 50 inches. To pass, the lens must not crack, chip or break. All glass safety lenses must undergo this test. For plastic safety lenses, however, only a statistical sample of a large batch of lenses needs to be tested.

     

  • In high impact testing, a high velocity test is performed by shooting a quarter-inch diameter steel ball at the lens at a speed of 150 feet per second. To pass, the lens must not crack, chip or break, and it must not become dislodged from the lens holder.

 

Written by: Gary Heiting, OD, All about Vision. 

What Are Safety Glasses