Two prescriptions. One pair of lenses.
Yep, varifocals are impressive at helping you see near, far or anything in between.
But when it comes around to your next sun-filled holiday, what about a set of progressive sun lenses?
Same visual performance as your glasses. ✔
100% UV protective ✔
Good for driving ✔
So in this article, I’ve put together 4 tips about the considerations, details and benefits of wearing prescription varifocal sunglasses.
Click on any one of them if you’d like to jump ahead.
Table of contents
Polarised vs non polarised | UV protection | Darkness of tint | Finding your ocular centres
4 tips for buying progressive sun lenses
1: Polarised or not?
Polarised sun lenses contain an additional filter called a polariser.
It’s in-built within the layers of the lens and provides a significant advantage over non polarised sun lenses.
Very simply, the polariser layer blocks-out horizontally orientated light from entering your lenses. If you’re next to water or any flat shiny surfaces, reflected sunlight becomes condensed, horizontal and blindingly painful to look into.
By blocking-out this glare, polarised lenses can vastly improve the clarity of your vision and can help to reduce eye strain.
Non polarised lenses don’t contain this filter but they still equally protect your eyes from UV light. This makes them slightly cheaper but means that your quality of vision can be interrupted from sun-glare and harsh reflections.
Our prescription sun lenses can be either polarised or non-polarised, but the advantage speaks for itself.
2: UV protection
According to European standard: EN 1836:2005, sunglasses must provide 99-100% ultraviolet protection against the sun.
Sounds serious. And it is.
Just like a darkly lit room, the darkening tint of your lenses makes your pupils dilate. This lets in more light to help you see.
Lenses without sufficient UV protection means your eyes are even more susceptible to long term damage and even loss of vision. They’re literally being sunburnt, even though they’re behind a darkened lens.
Sun lenses must be rated as being UV40 or UV400 which indicates proper protection against ultraviolet light including UVA and UVB.
You’ll be glad to know that all Banton Frameworks sunglasses are 100% UV protective, whether they’re prescription or not.
3: Darkness of tint
Breaking news.
The darkness of your lenses has nothing to do with UV protection.
In fact, lenses can be nearly impossible to see through yet can provide you with next to no ultraviolet barrier. As mentioned in section 2, always check for the UV400 label.
The darkness of your sun lenses is measured as a percentage called visible light transmission. The refers to the amount of light that passes through a lens and is divided into 4 categories seen in the table below.
|
Category |
VLT% |
Sunlight |
Driving suitability |
|
0 |
80% – 100% |
Overcast |
Moderate |
|
1 |
43% – 80% |
Low |
Day only |
|
2 |
18% – 43% |
Medium |
Day only |
|
3 |
8% – 18% |
Strong |
Day only |
|
4 |
3% – 8% |
Very strong |
Never |
The darkness of your lens is entirely a personal preference and depends on how you use your sunglasses.
Category 4 lenses are illegal to wear whilst driving as they are too dark to properly see the road and any potential hazards.
For everyday use, a category 2 or 3 VLT is advised.
When placing your order, let us know what darkness of tint you’d like for your varifocal sunglasses.
4: Finding your ocular centres
Varifocals work hard to help you see.
It’s no surprise they need to be accurate and be positioned properly in front of your eyes.
Which is why it’s imperative that the middle of each of your lenses is directly aligned with each of your pupils. This is achieved through two separate measurements for your left and your right eyes.
Your ocular centre heights refer to the vertical positioning of each of your pupils behind the lenses of your sunglasses. From the bottom of the lens to your pupil, your height is measured in mm for each eye.
Your dual pupillary distance denotes the horizontal distance from the centre of your face to each of your pupils. This is measured in mm and provides the horizontal aspects required for locating your ocular centres.
This can be measured using our free PD ruler which you can download and print.
Oh and it’s mirror-friendly so you can read your measurements if you’re by yourself.
Free PD ruler download
Download this free PD ruler.
Summary
Considering a pair of varifocal sunglasses suggests you take your eyewear seriously.
Just like your spectacles, they’ll help you see at multiple distances whilst sufficiently protecting your eyes from the sun.
Polarised lenses aren’t necessary but have the distinct advantage of reducing reflected glare. This bonus will provide you with more consistent vision in various conditions and can help to reduce unnecessary eye fatigue.
Sunglasses must be fully ultraviolet protective to 99-100% and come with a certified indication of UV40/UV400 from the supplier or vendor.
Buying varifocal sunglasses online is perfectly ok, as long as your ocular centres have been integrated from your pupillary distance and heights.
Armed with this information, you can select a new pair of progressive sunglasses in the knowledge they’ll be safe, accurate and to your personal requirements.
For more information about polarised sunglasses, you should check out our sunglasses blog section.
Thanks for reading and sharing this article.
