Lens Materials
Polycarbonate
This material is the most commonly used in prescription safety glasses as it has the highest impact rating and is available in a variety of lens designs.
Trilogy/Phoenix/Trivex
Generically this material is known as Trivex and it has excellent optical qualities. It surpasses the requirements of ASNZS1337.6 for medium impact protection and is also available in a variety of lens designs.
CR39 (Columbia Resin #39 or allyl diglycol carbonate)
One of the most common lens material used in optics today with exceptional optical qualities and is available in a wide variety of lens designs. It is however only compliant for low impact protection.
Lens Designs
To provide the best alternatives we need to offer options. The four most common lens options provide a range of vision correction that is generally suitable for all workplace tasks and prescription variations.
Single Vision
This lens provides the same power throughout the entirety of the glasses. Commonly used for reading glasses or driving/long distance, this lens design provides a beneficial option but does have some limitations in only correcting to a single focal length.
Bifocal
As its name suggests this lens has two focal lengths. Typically the top of the lens is used for distance vision and the bottom of the lens for near vision. A flexible option not used a lot in fashion glasses, but still has a very applicable position in prescription safety glasses.
Progressive
The next step from a bifocal, this lens provides the wearer with a progressive transition between the top (distance correction) and bottom (near correction). It supplies the wearer with every prescription they need to see clearly in the one lens. All that is required is for the user to focus through the correct part of the lens for the distance they are looking. By varying which section of the lens they are looking through, the wearer is able to focus at any distance and always find a clear image.
Enhanced Reader
Commonly called an 'access' lens or 'occupational multifocal' this lens offers the wearer two distinct focal lengths. The top section of the lens is dedicated to an intermediate distance (arm’s length) and the bottom section to a closer reading distance (typically 400-500mm from face). Perfect for those computer users or those who need to focus up close as well as at arm’s length. It is generally not able to be used for walking around.
Lens Colours
As there is in fashion glasses, there are also lens colour options available in prescription safety glasses. Typically there are four main alternatives.
Clear
As you would expect these lenses have no colour filter and allow almost all light to pass through them.
Transition/Colour Changing
This option is very popular as it provides the wearer with a pair of lenses that change colour depending on the conditions they are exposed to.
Permanent Tint
This option is limited to a selection of the frame models available as not all lenses are able to be tinted this way. Essentially the lenses are dyed to the desired colour.
Polarising Tint
As sunglasses these provide an effective filter to bright light being reflected up from the ground. Very effective around water and other surfaces where light can bounce up from the immediate surroundings (roads, concrete pads, sand, etc.)
