This blog will teach you about polarized lenses the good and the bad.
What is polarized light.
Polarized light occurs when scattered light reflects off any flat horizontal shiny surface like water in a lake, a car windscreen, sand, snow, concrete and asphalt roads. Glare or polarized light reduces visibility, distorts colour and makes vision uncomfortable and painful. It has not been shown to cause eye problems.
The white polarized glare shinning off the top of the water in this picture distorts the true colour and would be total eliminated with high quality polarized lenses. While low quality polarized lenses would eliminate as little as 30% of this glare.
In theory polarized lenses should be better than plain lenses but in reality that is not the case. Low quality polarized lenses do cause headaches, distort vision and lead to eye problems and blindness.
Polarized lenses and UV protection.
Note that polarized lenses are no better or worse than plain lenses at eliminating harmful UV radiation, just make sure you only buy sunglasses with *100% UV protection between 280Nm and 400Nm. *(Note: UVC From 100Nm to 280Nm is totally absorbed by the earth’s atmosphere). So total protection is essential especially for kids. *Let me be clear, that means all UV rays between 280Nm to 400Nm. Not:- UV400, UVA, UVB, UVC or the USA and EU standard UV 280Nm to 380Nm. You can read more about UV protection here: Sunglasses the good and the bad
How polarized lenses are made.
Low quality polarized lenses.
Really low quality polarized lenses are made from laminating the polarized film (a very soft PVA material that is heated and stretched to form long chain molecules, causing them to align in one direction) is then sandwiched between thin sheets of acrylic or TAC (acetate).
These cheap polarized lenses scratch really easy and have distortion due to the thin lens distorting the polarized film which causes headaches and eye fatigue, a common problem reported by many customers. Due to the distortion and low quality polarized sheet material used in these lenses they do cut as little as 30% of the reflected glare. Worse still the distortion from these lenses does lead to major non-reversible eye damage requiring the need for prescription glasses to see.
These lenses must be avoided, especially for children who are harder on sunglasses and will scratch the soft lenses and these scratches will cause even more *stress to the eyes. Many of these cheap lenses also use a UV coating on the lens that children will scratch very quickly leaving no UV protection at all.
*(When a scratched lens is being worn the scratch appears as a blur in the image. The brain is not happy with the blur so a small signal is sent from the brain to the ciliary muscle (a small muscle that circles the lens of the eye) to adjust the lens of the eye for a clearer picture. Of course the blur remains. So the brain sends another signal to readjust and this repeats continuously until the scratched lens is removed. Once the small ciliary muscle wears out the only way to adjust vision is with prescription glasses.
How to know if it is a cheap polarized lens.
- The material name, TAC (Tri-acetate cellulose).
- Press your finger tip on the centre of the outside surface of the lens. If it deflects under a little pressure it is a cheap lens that will distort vision.
- Tap the lens with you finger nail. If the sound is a dead thud it is a cheap lens. Hard lenses will ring like glass when tapped.
High quality polarized lenses.
High quality polarized lenses start with the same process of heating and stretching a soft PVA material to form long chain molecules, causing them to align in one direction. But done very accurately with high quality material so it will eliminate all polarized glare. This polarized sheet is then laminated between two high quality polycarbonate, trivex, CR39 or glass lenses.
These lenses do not require a UV coating that will scratch off as the UV protection is evenly distributed throughout the lens. To avoid distortion of the polarized film the finished lenses should be at least 2mm thick. Don’t buy thinner lenses they will cause headaches and eye fatigue, a common problem reported by many customers. Of cause these high quality polarized lenses do cost more.
How to know if it is a high quality polarized lens.
- The material name, polycarbonate, trivex, CR39 or glass.
- Press your finger tip on the centre of the outside surface of the lens. It should not deflect under pressure.
- Tap the lens with you finger nail. The sound of a hard lenses will ring like glass when tapped.
- Important – Check the polarized lens is horizontal with the frame and it is a polarized lens. To do this you will need two pair of polarized sunglasses. Place the two sunglasses facing each other and horizontal. You should be able to see clearly through both lenses facing each other. Slowly rotate one sunglasses lens till it is 90 degrees with the other lens whilst looking through it. It should go from clear to dark and not transparent. If it does not change and go darker then one or both lenses are not polarized. If the lens goes completely dark before reaching 90 degrees the lens in one or both sunglasses has not been installed correctly. Don’t buy them as it will not filter the polarized light effectively. Then check the other lens the same way.
Our recommendation – Polarized Lenses the good and the bad.
Eye sight is important and low quality polarized sunglasses that will damage eyesight cost similar to high quality plain lenses sunglasses that will protect eyesight. So buy the high quality plain sunglasses. If you can afford the high quality PC polarized sunglasses that will eliminate reflective glare, then buy these.
To give you an indication of the price on high quality adult PC polarized sunglasses, these start at A$140.00 up to A$700.00 or higher depending on the brand. Our Idol Eyes Australia baby polarized sunglasses using the same high quality PC polarized lenses start at A$95.00 Any prices lower than I have indicated will only be low quality polarized and should be avoided if you care about your or your child’s eye health.
Myths about polarized lenses. – As seen on many websites by those with no experience in optics.
- Polarized lenses are made with a polarized coating. No, totally false.
- Polarized lenses have a special chemical applied to them to filter light. Totally wrong.
- Polarized coatings darkens the lens. Wrong.
- Polarized lenses aren’t available for regular reading glasses. Wrong.
- Darker lens colors provide higher levels of polarization. Wrong.
- Polarized lenses cut more UV radiation than plain lenses. No, not necessarily. Polarization has nothing to do with UV radiation. (Polarized lenses help eliminate polarized light or glare.)
- Polarized sunglasses are better than plain sunglasses. No, it firstly depends on the quality. But if both are high quality, the polarized lens will eliminate that horrid glare. And if they are low quality polarized lenses you will end up with headaches, distorted vision all leading to eye problems and blindness.
- There are those who say that polarized lenses make them feel dizzy or disoriented. That is only caused by cheap distorted polarized lenses.
Don’t miss the latest sunglasses “WARNINGS” at the top of the home page. They will save your child’s eyesight. This is updated when we see any problems regarding standards and sunglasses.
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