The Difference Between Various Rx Safety Lens Types
Eye safety is one of the top concerns for safety managers making safety eyewear a critical piece of safety equipment. There are are many things to consider when choosing safety eyewear options for your employees. Did you know that safety eyewear can come in the form of regular safety glasses or prescription safety glasses?.
Prescription and non-prescription safety glasses may perform the same basic function but they are not created equal. In the case of prescription safety glasses, the materials selected for the lenses must not only keep foreign objects away from the wearer’s eyes, but also allow for him/her to see the work at hand in a clear and crisp way.
Safety managers should be aware of these differences because the options available will be specific based on the whether or not the glasses are prescription. Here are some valuable details about the diverse alternatives for prescription safety lenses.
Materials for Rx Safety Glasses
One of the most popular and widely sought after materials for prescription safety eyewear is polycarbonate. Not only is this material offered in almost every color option, but it is also one of the thinnest and most impact resistant choices. However, a downside is how easily it can become scratched from regular wear. This medium-index material is considered to be a middle ground between standard and high index plastics.
Generally found to be the cheapest safety lens material, standard plastic is the easiest to turn into a prescription lens. It is low-index and very scratch resistant, which makes this an excellent choice if the biggest needs are bulk quantities and accessibility.
Not only is high-index plastic more scratch resistant than standard, it also boasts a much thinner size which helps to make glasses lighter. Still, there are some negative aspects; they are significantly more expensive than standard, they are not available in as many color combinations and it is tough to find them as bifocal or polarized.
Introduced in 2001 as a competitor to polycarbonate, Trivex has some similar characteristics and some variances. The main similarities are that they are lightweight, high impact resistance and 100% UV protection. Meanwhile, they have different optical clarity due to Trivex being created in a mold, which allows for a crisper image. Because Trivex is a relatively new player there are not as many color options.
Testing Rx Safety Eyewear Options
All protective eyewear falls under one of two performance classifications: basic impact or high impact.
- Basic impact is tested via the “drop ball” test. The test is administered by dropping a one-inch diameter steel ball from 50 inches away directly onto the lens. As long as the lens is not chipped, cracked, broken or dislodged from the lens holder or frame it passes.
- High impact is tested with a high velocity test. This is performed by shooting a quarter-inch diameter steel ball directly at the lens at 150 feet per second. The lens passes that there is no chipping, cracking, breaks or separation from the lens holder/frame. Lenses that have passed will have a “+” mark to indicate high impact approval rating.
In spite of all the similarities between the various types of lens materials, the most important aspect when it comes to any safety equipment is making sure you get the right tool for the right job. Reviewing these valuable details on lenses can help you make that final decision.