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Sunglasses Facts

The aim of this article is to provide a complete reference guide to buying your sunglasses. In addition it will turn you into a witty, attractive person who gets invited to all the best parties - so get reading !

Which style will suit your Face Shape?

There is some great advantages to being able to buy sunglasses online - it is quick, convenient and you always have access to the latest styles and offers! However we appreciate that there is a major downside - you cannot try the sunglasses on before you buy. To make the decision even easier we have provided you with this straightforward guide to what styles will suit you best, based on your face shape. We hope that this will assist you in your choice of sunglasses!

There are 7 basic types of face shape and we have styles which will suit them all . The better matched your sunglasses to your face shape, the more they will flatter your best features and the better you will look!

The 7 face shapes

1. Oval
  Description:
• Balanced proportions.
• Chin is slightly narrower than the forehead.
• High cheek bones.
Look For..
• Frames should be as wide as the broadest part of the face.
• Frames should be the same proportion as the face.
• More frames suit this shape than any other!
 
2. Round
  Description:
• Few angles.
• Full face.
• Width and length in same proportions.
Look For..
• Slightly angular (slight cat eye shape), will narrow and lengthen the face.
• Avoid round or very square styles which exaggerate roundness.
• Frames should be wider than they are deep.
• High frames work well.
 
3. Diamond
  Description:
• Small forehead.
• Wide temple area.
• Face narrows to a small chin.
Look For..
• Frames that are heavy on top will widen the appearance of the forehead and jaw.
• Square, oval and rimless frames are great choices.
• Frames also shaped with a straight top and curved bottoms are great for you.
 
4. Triangle
  Description:
• The jaw is the largest part of the face.
Look For..
• Frames should add width to the forehead while softening and narrowing the appearance of the jaw, chin and cheeks.
• Square, aviators, or semi-rimless styles work well.
• Up swept cat eye styles would work well.
 
5. Heart
  Description:
• Wide forehead.
• High cheek bones.
• Face narrows to the chin.
Look For..
• Light colours and rimless styles are effective.
• Frames with round tops and square bottoms will work well and aviator or butterfly styles.
• Avoid heavy, thick frames.
 
6. Oblong
  Description:
• Face shape is longer than it is wide.
• Face is narrow and jaw and cheek bones the same width.
Look For..
• Frames should have top to bottom depth ie cover a lot of the mid section of the face
• To soften the face, try round, deep or low triangle shapes
• Decorative or contrasting frame arms can also achieve the widening
 
7. Square
  Description:
• Strong jaw line • Broad forehead.
• Wide chin and cheekbones.
• Width and length are same proportions.
Look For..
• Gently curved narrow styles will minimize square ness and add length.
• Frames should be more horizontal that vertical.
 
Other considerations

The size and shape of your nose can also affect which style might accentuate your best features.

• If you have a large nose, large oversized frames are recommended for balance. Small frames will accentuate it. .

• If you have a long nose, frames with side arms that draw attention to the temples, away from the nose are a good choice. A double bridge helps the nose appear shorter.

• A high bridge in a light colour lengthens a short nose or one that is small in proportion to the rest of the face.

Shades and Tints

Now you have hopefully chosen your frame you need to choose your tint ! Here is a quick guide to what tint you should aim for.
 
Smoke Dark Tint for daytime (bright and sunny days); decreases sunlight without distorting colors.
   
Clear For low-light or nighttime, untinted for indoor or outdoor use.
   
Yellow For overcast days, increases visibility and depth perception.
   
Flash Mirror Lens With a partial mirror coating, used for both bright and low light.
   
Smoke Mirrored Smoked lens with a partial mirror coating.
   
Revo Mirrored Revo Mirrored lenses are a multi-layered titanium which provides a brilliant rainbow color. Discovered by aerospace engineers at NASA, these high-tech lenses have 12 layers of titanium dioxide and silica applied onto shatterproof polycarbonate. They are also scratch resistant.
   
Amber Mirrored Amber lens with partial mirror coating. Amber lenses enhance contrast, enabling you to make out shapes, objects, and bumps in the snow more clearly because it blocks out the blue, or hazy, end of the color spectrum.
   
Rose Mirrored Rose lens with partial mirror coating. Rose lenses enhance contrast, enabling you to make out shapes, objects, and bumps in the snow more clearly because it blocks out the blue, or hazy, end of the color spectrum.
   

The History of Sunglasses

History says that Nero Claudius Caesar was the one who created the necessary prerequisites for the appearance of sunglasses prototype. It is believed that the Roman emperor liked to watch gladiator fights through polished gems.

However, sunglasses were first used in China in the 12th century or even earlier. The "lenses" of those sun glasses represented flat panes of sooty rock crystal, therefore had no correctional power. Such sunglasses were worn only for eyes protection purpose, as from damaging and intolerable sun glare. Also, according to some well-placed sources sunglasses served as a shield from evil spirits. Contemporary writings describe the use of such sun glasses by judges in Chinese courts as a protection, which offered them to keep secret their facial expressions while questioning witnesses.

James Ayscough, eyeglass designer, started using tinted lenses in spectacles in the middle of 18th century. Only around 1752, Ayscough discovered that white lenses caused irreparable harm to eyes retina, thus he advised the use of green and blue glasses, which had power to correct vision problems. As a consequence, it is considered that Ayscough glasses were the first real sunglasses. Sam Foster was that man who sold the first pair of sunglasses at the Woolworth on the Atlantic City Boardwalk. But sunglasses peak of popularity started only in the 1930s.

However, polarized sunglasses started to be manufactured only after Edwin H. Land had invented the first modern filters to polarize light. In 1936 Land began to use numerous types of Polaroid material in sunglasses and other optical devices.

Essential information about protecting your eyes (and a great party ice-breaker)!

Factoids

1. Ultraviolet rays are the most dangerous type of radiation. The majority of UV rays are absorbed by the atmosphere, but the quantity filtered is very variable. Those people nearest the equator and at high altitude will be in a thinner atmosphere. The effects of UV radiation are increased if reflected by surfaces such as snow, sand and water .

2 Water reflects approximately 20% radiation and sand reflects approx 10%. Snow reflects 85% and the intensity of the UV rays increases by about 10% with every 1,000 metres of height gained. It is advisable to have high wrap glasses in the mountains. The higher the relative humidity, the more dangerous the radiation.

3 Children, especially very young children have more fragile eyes than adults. UV absorption is total in babies and high under 13 years.

4 The tint in sunglasses is protecting you against dazzle, which is necessary in itself but dazzle is not harmful to the eyes. Lenses can give total UV protection even when clear. Heavily tinted glasses can do more harm than good as they cause the pupil of the eye to dilate so much, allowing in a lot of UV if the glasses do not have an adequate UV rating.

5 Lenses that are declared as optically correct are able to transmit a laser beam through them to a centred target with complete accuracy, and not deflect the beam off at an angle. Some lenses cannot do that, which can result in you misjudging your step when walking and making errors when driving.

What is UV?

UV (Ultraviolet Radiation) consists of the short, invisible rays from the sun that reach the earths surface. These rays contain three separate bands: UVA (315-380 nm), UVB (290-315 nm) and UVC (100-290 nm). UVC rays are absorbed by the earths atmosphere and do not reach the earths surface and therefore do not relate to sunglass performance. UVB rays are the " sunburn " rays. Exposure to UVB rays can potentially produce harmful effects to your eyes and may be associated with cataracts and retinal damage. UVA rays are mostly absorbed within the lens of the human eye, debate over the potential effects of UVA exposure continues within the industry. Sunglass standards place limits on UVA and UVB exposure . UV radiation is strongest at high altitudes, low latitudes and in open or reflective environments (sand, snow or water).

Are the designations "CR" and "Hard Resin" essentially the same thing ?

Generally speaking yes. Both CR-39™ (A registered trademark mark of PPG, which stands for Columbia Researchs 39th version of the formula) and Hard Resin (the generic term for standard plastic lenses) are made of a clear, water like liquid (diethleneglycol - allycarbonate) that are part of the thermosetting family of resins. In order to turn into lenses, the resin must be poured into a glass mould and then cured or polymerised in an oven and the resin hardens. Many companies have their own formulations and processes to make Hard Resin lenses.

How is polycarbonate different from CR-39™ ?

Polycarbonate is a tough, dimensionally stable, thermoplastic, while CR-39 ™ / Hard Resin is a thermoset polymer . Polycarbonate is processed by injection moulding. Polycarbonate pellets are heated, injected into stainless steel moulds under pressure and compressed to form a lens. All polycarbonate lenses must be scratch coated, as the uncoated material is susceptible to abrasion. Polycarbonate is lighter in weight and more impact resistant than Hard Resin. Hard Resin tends to be easier to edge and can be tinted (dyed) to a wider variety of lens colours.

What is the difference between "Bent Sheet" and "Injected" Polarized Polycarbonate?

Bent Sheet (thermoformed) polarized polycarbonate lenses are made by placing polarized film between two thin, flat sheets of polycarbonate material. A lens is formed by cutting out a particular size from the sheet and then heating the lens on a bending tool to achieve the required base curve (thermoforming). Injected polarized polycarbonate lenses are made essentially the same as standard polycarbonate lenses (injection moulding) with the introduction of the polarizing film in the lens mould, instead of lamination. The result is the injected lens provides superior Class 1 optical performance with the film as part of the finished lens.

What is TR90 ?

TR-90 is a superior compound which has no risk of toxicity or allergy and is FDA and BGA approved. It is extremely light weight and designed to flex making it resistant to stress cracking and material fatigue. It is free of plasticizers and extremely stable to UVA exposure in all types of temperature and humidity conditions. Strong resistance to chemical products such as solvents, alcohol, cosmetics and organic acids gives TR-90 maximum durability in outdoor environments.

What is an optically-decentered lens ?

Optically Decentred Diagram

Optically-correct decentred lenses provide superior optical clarity.

They achieve this by undergoing a process where the thickness of a deeper base curve lens is horizontally tapered from the bridge area and becomes thinner at the outer edge of the lens near the hinge.

This process eliminates prismatic distortion by shifting the optical sweet spot of each lens from the mid-point of the lens to directly in front of the eye.

Disclaimer: All content on this website is provided for general information only and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. I-sunglasses Limited is not responsible or liable for any diagnosis made by a user based on the content of this website. Always consult your own GP if you're in any way concerned about your health.