Would Your Sunglass Lenses Survive a Run-In with a Tree Branch?
Impact Resistance Explained
Eyes are a very precious commodity, and something you probably take for granted. But we're all just one line drive, one whipping tree branch, or one flying piece of debris away from serious ocular trauma.
Luckily, you have great options when it comes to getting protection from your eyewear.
While the size of a lens plays a part in how much coverage you’ve got, the most important factor is the ability of the lens to absorb a blow, otherwise known as its impact resistance.
In the US, there are two levels of impact resistance for commercial sunglass lenses—basic impact resistance and high-impact resistance.
This article will go over the tests needed to comply with these certifications and their real-world implications.
Basic Impact Resistance: Z80.3
The ANSI Z80.3 seal of approval encompasses more than impact resistance, testing things such as UV protection and clarity. But for the purpose of this post, we’ll focus on the impact resistant portion of the American National Standards Institute (ANSI) rating.
The requirement for lens strength or safety was actually set by the Federal Drug Administration (FDA) and is the highest impact requirement of any nation. The test, commonly known as the “drop-ball” test consists of a 5/8 inch steel ball weighing .56 ounces (15.87 g) being dropped on the lens from a height of 50 inches (127 cm).
The ball is usually guided by a tube that must end at least four inches (10 cm) above the lens and cannot impede the progress of the ball in any way.
To pass the test, the lens must not fracture, chip, or crack.
A more likely scenario is falling rock while you're belaying or debris thrown up in a strong wind.
At Revant, we have our own beefed up version of the Z80.3 test that we lovingly refer to as "The Punisher". Check out the video to see it in action.
High Impact: Z87.1
Z87.1 covers personal eye and face protection, and while it is often associated with safety glasses, sunglasses may be tested for the same requirements. Sunglasses that meet the ANSI Z87.1 standards are relevant to far more than OSHA (Occupational Safety and Health Administration) regulated work environments. In order to receive this certification, lenses must be tested in the frames and must pass two different levels of testing for impact resistance—high mass and high velocity.
In this test, a steel spike one-inch in diameter and weighing 17.6 ounces (498 grams) is dropped through a tube from a height of 50 inches (127 cm) onto a lens mounted in a frame. The frame is "worn" by an artificial head form.
To pass, the lens cannot crack, chip, or break and it must stay within the frame. Also, the lens must not make any contact with the head form.
This would be equivalent to crashing your bike and falling headfirst into your handlebars, or colliding with a low-hanging tree branch.
This test involves shooting a quarter-inch steel ball at the lens and frame at a velocity of 150 feet per second (roughly 102 miles per hour or 164 kilometers per hour) from a distance of just under 10 inches (25 cm).
The test is repeated multiple times (each time with a new frame and lens) at different angles and positions of impact. To pass, the lens must not crack, chip or break, and it must not become dislodged from the frame.
Outside the lab, this is equivalent to a tipped foul ball, or a tricky grounder that gets away from you and pops up into your face.
Also, it should be noted that in order to be Z87.1 certified both the frame and the lenses, assembled by the manufacturer, must pass the test. You can install Z87.1 lenses into frames without this safety rating, but this does not make them compliant with ANSI and OSHA requirements for safety eyewear.
Revant Replacement Lenses
Do you have a pair of scratched or damaged lenses that need to be replaced? Rest assured, all of our replacement lenses provide impact resistance, meeting the American National Standards Institute (ANSI) Z80.3 impact resistance standard.