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Frames and lens colour, what’s best and why?

Idol Eyes Australia blog – All about sunglasses and eyes

Frames, what’s best and why?

Frames are a vitally important part of sunglasses especially for babies and children. They don’t just need to look good they also have to handle the every day punishment that will come their way. They should not break easily. They have to be super comfortable or babies just will not wear them. They must give great UV protection. They should be light weight. This is just some of the criteria we think about each time we design a new sunglasses frame.

With more than 30 years experience making baby sunglasses and even longer making prescription eyewear we have tried all types of materials for the frames. Only a small number of materials pass our strict requirements allowing us to give our legendary 3-year guarantee. So the list is:

  1. Baby sunglasses – Rubber or rubber like materials. These are super comfortable and virtually unbreakable. With the aid of a headband the frame will contour to the shape of the face to eliminate UV rays from entering around the side of the frame.
  2. Toddler sunglasses – Rubber or impact resistant polycarbonate. Rubber has all the benefits mentioned above. Polycarbonate is 10 times more impact resistant than plastic, it is used in banks for its bullet proof qualities and is light-weight for comfort. Can be painted or printed making it a great material that lasts well.
  3. Kids sunglasses – Polycarbonate or optical quality steel. Polycarbonate has all the benefits mentioned above. 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?

Without good quality lenses your 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 that are made to world standards can cause blindness. (See our earlier blog – The dangers of poorly made sunglasses).

Lens material.

We only use A-grade impact resistant polycarbonate. I do suggest that you read our Critical points to look for when buying baby – toddler sunglasses to find out why.

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

lens blanks
lens blanks

This blank lens allows all of the distortion during cooling, due to “shrinkage” to occur at the outer edge, which is then cut off when the blank is cut into the shape of the frame.

G-15 lens, cut into shape
G-15 lens, cut into shape

This first lens is classed as A-grade. The waste material which has been cut off is usually sent to a waste recycling plant. Due to the nature of polycarbonate (it does not recycle well) this waste is not used to make more lenses. But some companies in order to make a higher profit do recycle this waste material 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 C-grade 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. All B-grade lenses will over a short period of time show signs of “crazing”, the term used to describe this. You can see this crazing in the lens in certain light, small web-like miniature cracks all over the lens. While C and D-grade lens can even show this “crazing” when new. The old saying, “You get what you pay for” is again true but not always, I have also seen really expensive sunglasses “craze” as well. Normally by brands that have no knowledge of how a pair of sunglasses are made, they try to buy the lowest price they possibly can, so they can make a large profit. Then they sell their really cheap product at a high price so the consumer will be mislead into believing the quality should be good. This crazing reflects shards of light into the eyes of the wearer making these sunglasses extremely uncomfortable and dangerous to wear.

Lens colour.

Another important aspect of lenses is the colour and also the darkness which will determine the amount of light that the lens will transmit. We know that 10% of all boys and 2% of girls are colour blind and if you buy sunglasses with the incorrect colour 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 achieve this. That colour is known as G-15. G, for neutral green and 15, for 15% light transmittance. Why do we only suggest neutral green? 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 in the lower end of the spectrum, say a blue or grey lens, these will distort colour in the higher end of the spectrum, red and yellow. And the exact same thing happens if you pick a lens in the higher end of the spectrum, say a red or yellow lens, these will distort colour in the lower end of the spectrum, blue or violet.

Lens category.

This refers to the darkness of the lens and 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 not made correctly.

 

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