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Frames, lenses what’s best and why?

This blog will teach you how to buy high quality sunglasses that will protect your baby and kids eyes from harmful UV radiation. The frames, lenses what’s best and why?

Frames, what’s best and why?

Frames are a vitally important part of sunglasses especially for babies and children. Besides looking great they must handle the every day punishment that will come their way. Break proof, because toddlers will always test their strength. And they must be super comfortable or babies simply will not wear them. Another critical point is good eye coverage to give maximum UV protection. They also have to be light-weight for extra comfort on little noses. And this is just some of the criteria we think about each time we design a new sunglasses frame.

The frame material.

We have more than 34 years experience making baby sunglasses and even longer making prescription eyewear. During this time we have tried all types of materials for the frames. But only a small number of materials pass our strict requirements that allow us to give you our legendary 3-year guarantee. So the material list is:

  1. Baby sunglasses – Rubber or rubber like materials. These are super comfortable and virtually unbreakable. By adding a headband the frame will contour to the shape of the face to eliminate all UV rays from entering around the side of the frame. The headband will also keep them in place.
  2. Toddler sunglasses – Rubber or impact resistant polycarbonate. Rubber has all the benefits mentioned above. While polycarbonate is 10 times more impact resistant than plastic. It is also used in banks for its bullet proof qualities and it is extremely light-weight for comfort. Also, it can be easily painted or printed making it a great material for sunglasses frames that will take all the punishment toddlers will hand out.
  3. Kids sunglasses – Polycarbonate or optical quality steel. Polycarbonate has all the benefits mentioned above. And optical quality steel allows us to make adult metal styles like aviators or club-masters etc. for kids that will not bend out of shape or break easily.

Lenses, what’s best and why?

With poor quality lenses you are just gambling with your child’s eyesight. The consequences are disastrous from terrible eye diseases like cataracts, pterygium, actinic & droplet keratitis, pinguecula and macular degeneration to blindness. Even buying sunglasses made to world standards can cause blindness. Please see our earlier blog – The dangers of poorly made sunglasses.

The lens material.

We only use A-grade impact resistant polycarbonate lenses. Why? Because polycarbonate lenses have great UV protection. They will take all the punishment kids will give sunglasses. This gives you great value for money. But please only A-grade lenses.

How A-grade lenses are made.

What is an A-grade lens? Firstly you must understand how a lens is made. To make a good quality lens you have to make a round blank lens from “virgin” polycarbonate.

lens blanks
lens blanks. in different colours

The polycarbonate material is purchased as small pellets. These small pellets are heated in an injection moulding machine and then forced into the lens mould. The round blank lens allows all the distortion during cooling process, due to “shrinkage” to occur at the outer edge of the lens. All this distortion is then cut off when the round blank lens is cut into the shape of the frame. This first lens is classed as A-grade and is distortion free.

Frames, lenses what's best and why? G-15 lens, cut into shape.
G-15 lens, cut into shape

The waste material from A-grade lenses (which is the cut off material between the round blank and the lens cut to the shape of the frame) should be sent to a waste recycling plant. Why? Because polycarbonate does not recycle well. And this waste material should never be used to make more lenses.

How lower B-grade lenses are made.

Some companies in order to make a higher profit do recycle the waste material from A-grade lenses to make more lenses. This second made lens is classed as B-grade. I have heard that the waste material from this B-grade lens is recycled again to make a C-grade lens and recycled again to make D-grade lenses. Recycling sounds great, right? The problem is polycarbonate is extremely impact resistant and the extra heating and cooling during the injection process makes the lens extremely brittle.

Why you should avoid low quality B, C or D grade lenses.

When the lenses are fitted into the sunglasses frame properly there must be a slight interference. This interference fit stops the lenses from popping out of the frame.

But due to the curve of the lens the pressure from the frame causes different forces on the inside and outside curves of the lens. Namely these forces are compression on the inside curve of the lens and torsion on the outside curve of the lens. Because B-grade lenses are extremely brittle these differing forces cause small web-like miniature cracks all over the lens called “crazing“. This does occur over time. You can see this lens crazing in certain light. C and D-grade lens can even show this “crazing” when new.

This lens crazing distorts vision and reflects shards of light into the eyes of the wearer making these sunglasses extremely uncomfortable and dangerous to wear.

The old saying, “You get what you pay for” is again true but not always. I have seen really expensive sunglasses “craze” as well. Normally by brands that have no knowledge of how sunglasses are made. They buy sunglasses at the lowest price they can, (from some Asian factory) so they can make a larger profit. Then they sell their really cheap product at a high price so you the consumer will be mislead into believing the quality is good. So please be careful.

A simple hammer to test lens brittleness.

This following video show the difference between a polycarbonate A-grade lens VS a polycarbonate B-grade lens. Note: that lower grade C or D lenses are even more brittle than B-grade lenses.

Lens Test: Polycarbonate (PC) A-grade VS. Polycarbonate (PC) B-grade lens.

Lens colour, what’s best and why?

Another important aspect of lenses is the colour and the darkness of the lens that will determine the amount of light the lens will transmit.

We do know that 10% of boys and 2% of girls are colour blind. And if you buy sunglasses with the incorrect colour lenses for these kids you compound the difficulties for them to distinguishing and learn colours. So, unless your child has been tested for colour blindness or you simply want the best colour lens to reduce glare and not distort colour only one colour lens will do this. That colour is G-15. G, for neutral green and 15, for 15% light transmittance. Why do we only suggest neutral green? Put simply this colour is in the middle of the visible light spectrum as seen in the in the colour chart below, which causes less distortion in all colours of the rainbow.

visible light spectrum
visible light spectrum

If you pick a lens colour in the lower end of the spectrum, say a blue or a grey lens, these will distort colour in the higher end of the spectrum, red and yellow. And the same thing happens if you pick a lens colour in the higher end of the spectrum, say a red or a yellow lens, these will distort colour in the lower end of the spectrum, blue or violet.

Lens UV protection, whats best and why?

Make sure you only buy sunglasses with *100% UV protection. Especially for kids. Let me be clear, that means all UV rays between 200Nm to 400Nm. Not: – UV400, UVA, UVB, UVC or the USA and EU standard UV 200Nm to 380Nm. *(Note: UVC From 100Nm to 280Nm is totally absorbed by the earth’s atmosphere). You can read more about UV protection here: Sunglasses the good and the bad

Please note: For young children the minimum UV requirements in world sunglasses standards are not good enough to give maximum protection. At this age total protection is needed to stop nasty UV related eye diseases. See why in this blog: How UV rays damage young eyes.

Lens category, what’s best and why?

This refers to the darkness of the lens and gives an indication of what the sunglasses are intended to be used for. For all general purpose sunglasses we recommend category 3 or cat #3. Please see our earlier blog, The dangers of poorly made sunglasses. This does go into depth about lens category with a chart of the different categories and the intended use. It also points out the dangers of buying sunglasses with the incorrect category that are made incorrectly.

Conclusion. – Frames, lenses what’s best and why?

With the helpful information in this blog you will be able to buy sunglasses that will fit comfortably, last well and help protect eyes. Or you could buy high quality Idol Eyes Australia sunglasses that have all these great features and fully tested. See our testing procedure here: https://idoleyes.com.au/our-blog/our-sunglasses-testing-procedure/

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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