Safety eyewear can avoid around eighty percent of impact related mechanical eye injuries, especially those caused by small or big flying objects.
Other types of eye injury such as chronic exposure to dust, chemicals and radiation account for thirty percent of eye injuries while flying objects cause seventy percent, according to Professor of Optometry, Stephen Dain of the Uni of NSW.
Safety standards are drafted with impact resistance in mind. The wearing of safety glasses tends to protect against the other eye injuries as a matter of course.
These safety standards apply to the frame and lenses, both separately, and together.
The frame and lens each has to meet appropriate standards, and the finished prescription product combining lens and frame has to as well.
The only products approved for high impact use are goggles or helmets. These are not well accepted by wearers.
So for safety frames, In practice, the frame is either approved as a low impact or medium impact frame, where the low or medium refers to the impact of a standard ball of steel at a standard speed on both the frame being able to hold the lens in place, by not cracking or breaking, the lens not shattering, and the combined safety spectacles not collapsing as well.
As each frame and lens pair cannot be destroyed to ascertain its safety, so certain laboratories have gained accreditation to fit approved frames and lenses to enable certification via their quality control, that the end product meets the standards.
Polycarbonate with centre thickness of two millimeters, is the gold standard lens for impact resistance, and the lens of choice for medium and high impact situations. In low impact situations, for example where glare, chemicals or dust is the main problem, acrylic or polyurethane based products, which both have less optical colour distortion qualities, may be used.
For a table of all eye hazard situations see the article “Eye hazards in the workplace”
Compliance with the Safety standards means the frame and lens comply but with no certification that the spectacles do, as certification comes only from specialised approved lens laboratories. See my separate article for more detail.
For relevant excerpts of the OHS Act (SA) 1986 see my article “OHS Act Employer responsibilities”