Polarised Lenses & Sunglasses Explained
Online Opticians UK believes everyone should own a pair of quality polarised glasses or polarised sunglasses. Polarised lenses do what no other lens or lens treatment can - block blinding glare.
In addition, polarised lenses can enhance visual acuity, colour contrast and visual comfort, and block 100% of harmful UVA and UVB light.
We’ve all experienced glare in our daily lives… perhaps spending the day at the beach, driving in a car with the sun reflecting off the dashboard, roadway or bonnet or on a boat with the sun illuminating the surface of the water,
Usually, this glare is annoying and uncomfortable on the eyes, but when the angle of reflection is just right, the glare can become blinding and often downright dangerous, as in the case of driving a vehicle.
Ordinary tinted sunglass lenses only cut down on ambient light that reaches the eye, or, light transmittance. By their very nature, they cannot block glare. Only polarised lenses can block out this dangerous, blinding glare.
To understand how, you will need to understand how glare works and how polarised lenses work.
What is Glare?
When light bounces off of a surface, its light waves travel in all directions. Some light travels in horizontal waves, while others travel in vertical waves.
When light hits a surface, typically light waves are absorbed and/or reflected in a random manner. However, if light hits a reflective surface (such as water, snow, even cars or buildings) at just the right angle, some of the light becomes "polarized" or 'polarization'.
This means that vertical light waves are absorbed while horizontal light waves bounce off the surface. This light can become polarized, resulting in glare that can interfere with your vision by striking the eyes intensely. Only polarised lenses can remove this glare.
What is a Polarised Lens?
Polarised lenses are laminated with tiny vertical stripes that only allow vertically angled light to enter the wearer's eyes. Glare is eliminated because the horizontal light waves cannot bypass the vertical filter.
Sunglasses and camera lenses are often polarised to reduce glare from surfaces, such as light reflecting off a lake or the bonnet of a car.
How Do Polarised Lenses Work?
When light bounces off of a surface, its waves tend to be strongest usually horizontally, vertically, or diagonally. This is called polarization.
Polarised lenses contain millions of parallel rows of tiny iodine crystals or dichroic dyes (so small they can’t be seen with the naked eye).
Like Venetian blinds, the horizontal rows of iodine crystals contained within the polarised lens block out horizontal polarized light waves, letting only (non-polarised) vertical light waves reach the eye.
Polarisation blocks as much as 50% of the light passing through a lens. The person looking through the lens can still see clearly in most cases, but it reduces the brightness and glare of light.
This results in comfortable vision with no glare, and is the reason why only a polarised lens can block glare.
Polarised Sunglasses vs Normal Sunglasses:
Normal sunglasses offer basic protection against bright light & UV rays but only polarised lenses block blinding glare and can also enhance visual acuity, colour contrast and visual comfort, blocking 100% of harmful UVA/B light.
Different Types Of Polarised Lenses:
Lenses can be polarised to different degrees and in different ways. Most inexpensive polarised sunglasses have a thin film applied on one side of the lens. Many higher quality lenses have film laminated between two layers of lens material, preventing it from being scratched or rubbed off. In addition, the more dense the film is, the more polarisation it provides.
In most cases, polarised sunglasses don't look any different from regular sunglasses. While denser films tend to be darker, the colour of a lens does not determine how much polarization it provides.
A very dark pair of sunglasses with a light film will not block more glare than a lighter shade of glasses with a denser film. The colour of the lens is also variable; although they cannot be made clear, polarised lenses can be made in grey, brown, green, or other colours.
Different Polarised Lens Options:
Polarised lenses are available in nearly all lens types, materials, coatings and designs, such as polarised varifocal lenses or polarised high index lenses and can be added to any frame type such as rimless glasses.
Pros & Cons of Polarised Lenses & Sunglasses:
Polarised Lens Benefits-
Drivers, fisherman, and photographers were some of the first to use polarised lenses.
- Reducing glare can ease the eye strain drivers feel from long hours on the road.
- Fishermen can often see under the surface of water using the lenses, which helps them to see fish or other objects.
- Photographers use polarising filters on camera lenses to enrich the images they capture by giving them more contrast, and to increase the range of effects they can produce.
- In addition to blocking blinding glare, polarised lenses can also help you to see better by improving contrast and visual comfort and acuity.
Polarised Lens Limitations-
- Because the polarising stripes reduce the amount of light entering the eye, these lenses should not be used at night or in other situations where clear lenses are required. It is not possible to make such lenses truly clear; even those with low levels of polarisation have a slightly grey hue.
- Polarised lenses can cause distortions in the way wearers see liquid crystal displays (LCDs), rendering some cell phone screens, clocks, and other displays unreadable.
- Pilots should not use polarised glasses because they can make flight instruments difficult to read and other objects in the sky — including other airplanes — less visible.
How To Buy Polarised Lenses:
Buying Polarised lenses and enhancing your visual acuity, colour contrast, visual comfort and also blocking out 100% of harmful UVA and UVB light is as simple as adding it to your lens options when creating your lenses. Polarised lenses cost from £49.00 depending on the type & brand.
Please don't hesitate to contact us should you require any further information and one of our advisers will be happy to assist you in selecting the correct lens options for your prescription, lifestyle and budget.
Freephone:0800 690 6220
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