Legitimate polarized sun lenses, rated as UV40 or UV400 will block 99-100% of ultraviolet rays emitted from the sun. Polarized lenses filter visible light for comfort, whilst UV protection blocks invisible and harmful ultraviolet light which is the most crucial function of sunglasses lenses.
To keep things simple, your primary concern for any sunglasses is UV (ultraviolet) protection which most good quality sunglasses provide. Polarization on the other hand is a secondary and optional benefit (which not all sun lenses provide) to block glare from flat reflective surfaces such as water or wet roads.
Polarized or not, if any sunglasses frame is labelled with a CE mark, it therefore conforms to the European standard: BS EN 1836:2005. This means that the lenses provide UV protection up to 380 nanometres.
A dense but fairly important introduction to this blog post, I know! But proper eye protection is super important for long term health.
To learn more about the various sunglasses standards and how they protect your eyes from UV light, this article provides everything you need to know.
Let's dive in.
Which is better, UV400 or polarized?
UV400 protection is the most important factor to consider when choosing sunglasses. This rating means the lenses have a coating which blocks 99-100% of invisible UV light, providing your eyes with optimal protection against UVA and UVB rays. (More on this further below.)
Polarization is a secondary benefit to UV protection which means the lenses have an additional layer within (or upon) them which blocks glare. This is a type of visible light which puts strain on your eyes but doesn't pose the same threat of damage like that of UV.
All sunglasses lenses should block 99-100% of UV light, but they certainly don't need to be polarized. For more information, check out this handy article.
What is UV light?
UV light stands for ultraviolet light, an invisible type of non-ionising radiation which comes from the sun. UV light is made of varying frequencies which range from 100 to 400 nanometres (nm) which, in the context of your skin and eyes, are the most damaging. This range of ultraviolet frequency can be defined as UVA, UVB or UVC as described below.
Why is UV protection important for sunglasses?
UVA and UVB rays are the most dangerous and can have profound effects on our eyes. Constant exposure to these rays without proper protection can lead to a range of ocular issues, including cataracts, macular degeneration, and even delicate cornea burns, known as photokeratitis.
UVC is the least damaging frequency of ultraviolet light and is predominantly blocked or absorbed by the earth's atmosphere. However, small portions of this light does get through, which is why UV400 sun lenses still cater for this.
|
UV light sub-type |
Frequency (nm) |
Danger to eyes & skin |
|
UVA |
315 - 400 |
High |
|
UVB |
280 - 315 |
Medium |
|
UVC |
100 - 280 |
Low |
Cataracts are a clouding of the lens in your eye, leading to decreased vision and, if untreated, eventual blindness.
Macular Degeneration is a condition that erodes the central portion of the retina, impairing central vision used for reading, driving, and recognizing faces.
Photokeratitis is akin to a sunburn for the eyes, a painful condition resulting from exposure to UV rays, causing temporary vision loss and extreme discomfort.
Understanding polarized lenses
In addition to UV protection, polarized lenses offer the distinct advantage of blocking glare.
This optional feature is primarily for visual comfort as it reduces the strain put upon your eyes when sunlight reflects off any flat reflective surface such as water, snow or ice. This is when light becomes condensed, making the light waves become horizontally orientated known as glare.
Within (or upon) polarized lenses is a chemical film called a polarizer which is made of microscopic rows of vertically aligned molecules. These rows only allow vertically aligned light waves to pass through the lens, thus providing glare-free vision.
Because the horizontal light (glare) can't pass through, polarized lenses are more consistent in varying light conditions. Over long periods of sun exposure, polarized lenses alleviate eye strain which would otherwise be strenuous on both your eyes and surrounding muscles.
If you spend a lot of time outside, near water, driving or playing sports, polarized sunglasses are a fantastic way to improve your visual experience. Whilst they provide UV protection like regular sun lenses, they're considered as a superior lens type which give better visual acuity and color perception.
Can you get both UV protection and polarized?
Yes, sunglasses can provide UV protection and polarization simultaneously. Whilst UV protection is mandatory, polarization is an optional upgrade which you can choose have incorporated to your sunglasses.
Depending where you get your sunglasses from, there are various types of UV protective polarized sunglasses available. These can differ in lens material, lens color and type of prescription.
Are there other sunglasses standards?
Despite being a European emblem, sunglasses bearing the CE mark are internationally recognised as being able to provide sufficient ultraviolet (UV) protection up to 380 nanometres.
However, there are actually three main international sunglasses standards for fashion frames which aren't intended for use as personal protective equipment (PPE).
These include;
- Australian sunglasses standard: AS/NZS 1067.1:2016
- New Zealand sunglasses standard: AS/NZS 1067.1:2016
- American sunglasses standard: ANSI Z80.3
FAQs
Is there a downside to polarized lenses?
While polarized sunglasses offer numerous benefits, their downsides include a higher cost, the darkening of LCD screens, reduced visibility in low light conditions and limited tint options. Due to the way polarized work, they have a habit of making digital displays appear much darker which can be annoying or even hazardous for certain scenarios.
To learn more about these disadvantages of polarized sunglasses, check out this helpful blog post.
When should you not wear polarized sunglasses?
Certain occupations such as pilots, or heavy machine operators shouldn't wear polarized sunglasses as they tend to darken LCD screens (liquid crystal displays). The polarizer film within or upon polarized lenses typically make it difficult to read digital information which is one of their main drawbacks.
What sunglasses block the most sun?
Sunglasses which block the most sunlight are UV400 lenses which prevent invisible ultraviolet light between 100-400 nanometres from entering your eyes. However, sunlight is also made of visible light which can also be absorbed by sun lenses, depending on their darkness.
Darker sun lenses absorb more visible light for visual comfort whilst lighter sun lenses absorb less visible light. This is what denoted their lens category ranging between 0 and 4.
Are darker sunglasses better for your eyes?
Darker lenses don't provide any more UV protection for your eyes. In fact, lens darkness simply determines your visual comfort by reducing how much visible light is absorbed. The darker your sunglasses are, the more visible light they absorb, thus reducing the strain put upon your eyes which can be helpful if you're sensitive to bright light.
Lens darkness is measured as a percentage of absorption known as ABS%. The higher this percentage, the darker the lenses are to look through.
You may have heard of sunglasses categories, which is what these varying ABS percentages determine. Lightly tinted lenses range between category 0, 1 or 2. Most sunglasses are category 3. Very dark mountaineering sunglasses may be category 4.
|
Category |
0 |
1 |
2 |
3 |
4 |
|
ABS% |
0% - 10% |
10% - 20% |
20% - 43% |
43% - 85% |
85% – 92% |
|
Tint |
Very light |
Light |
Marginal |
Dark |
Very dark |
|
Sun use |
Overcast |
Low |
Moderate |
Strong |
Very strong |
|
Driving suitability |
Day & night |
Day only |
Day only |
Day only |
Never |
Is polarized better for your eyes?
Polarized lenses aren't any more UV protective than regular non-polarized lenses. However, they can alleviate visual strain via their ability to block glare which is why their widely deemed as a superior type of lens.
Reduced glare results in less straining to see properly, which over long durations of exposure, makes for an easier more enjoyable visual experience. They aren't better for your eyes per se; they just give smoother optics.
Summary
- UV400 lenses block 99-100% of UV rays up to 400 nano metres.
- Polarized lenses block glare from reflective surfaces for visual comfort.
- The CE mark denotes conformity to EN 1836:2005 meaning lenses provide UV protection up to 380 nanometres.
- UV protection is mandatory. Polarization isn't
- UV light is an invisible type of non-ionising radiation emitted from the sun.
- UV consists of UVA, UVB and UVC light ranging between 100 to 400 nanometres (nm).
- Polarized lenses use a chemical film called a polarizer which block glare.
- Lenses can be both UV400 and polarized.
- Darker sunglasses aren't more UV protective.
- ABS% measures lens darkness.
Hopefully you found this article helpful. If so, please check out our other polarized sunglasses blog posts for more insights and advice.
Thanks for stopping by.