Many of us wear sunglasses every day, whether at work, during recreation, or driving. It’s not just their ability to reduce glare that makes them a must-have item, sunglasses also play a major role in reducing the risk of UV-related eye damage such as cataract and eye cancers.
However, there is much more to selecting an effective pair of sunglasses than you might realise.
What makes sunglasses effective?
Just as we have a sun protection factor (SPF) rating for sunscreen that tells us the level of UV protection provided, for sunglasses we have an eye protection factor (EPF). The higher the EPF rating, the better – an EPF of 9 or 10 provides excellent protection. You may also come across sunglasses labelled UV400. These are also an excellent choice, as this means the lenses block at least 95% of UV in wavelengths up to 400 nanometres.
In Australia sunglasses must be tested to the Australian/New Zealand Standard. (Note that this doesn’t include prescription glasses). The standard breaks down lens performance into 5 categories, from least to most effective in terms of UV protection and glare reduction. Look for categories 2 or higher, as this means the lenses absorb more than 95% of UV. (However, category 4 lenses are very dark special sunglasses and are not suitable for driving).
There is also an Australian/New Zealand Standard for eye protection for occupational applications. This also takes into account properties such as impact or splash resistance which are applicable in certain workplaces.
It’s not all about looks
The style of sunglasses can also affect performance. Styles such as wayfarers or aviators often sit forward on the face, and may have thin arms, both of which can allow stray UV radiation to enter the eye. To counteract this, wraparound styles that fit close to the face and/or have wide arms to block UV are recommended.
When it comes to lenses, darker doesn’t always equal better. It all comes down to the EPF or UV rating. The UV protection comes from the lens material itself not the tint. It’s not uncommon to find clear safety glasses that block 100% of UV.
To polarise or not to polarise
Polarisation works by applying a filter to the lens that reduces glare. The causes the lenses to absorb horizontal light waves, while still allowing vertical waves to pass through.
This not only provides general visual comfort, but also helps avoid blinding glare, which is particularly important in situations such as driving. Polarisation doesn’t provide UV protection, so even if your glasses are polarised, it still pays to check the UV protection.
What about cost?
Don’t be fooled into thinking that more expensive sunglasses automatically provide better UV protection. Sunglasses don’t have to be expensive to be effective, and remember that if they are purchased for work use, they can often be claimed as a tax deduction. Again, look for the EPF or UV rating.
So next time you’re in the market for some new sunglasses, keep these tips in mind and you can be sure yours are up to the task.
An edited version of this article was originally published in the summer edition of Master Builder Magazine.