Sunglasses these days are more than protecting the eyes from harsh sunlight, they have become an up-front fashion statement.
Like any fashion commodity, trends change swiftly and street-cool consumers need to antennae (and the cash) to stay in front of the theme.
One season the in-style trend will be flat, shield-like lenses and wide metallic temples, another will favour mirror flash lenses and deep rims.
Despite the seasonal variations (and these can be huge) the urban cool look never seems to drop out of style.
Urban cool designs can come in many forms but they tend to be either avant-garde or ultra-retro.
Some stars never seem to face and the Aviator, designed in the 1930s, is the daddy of them all. Made to protect the eyes of airline pilots they have become the most popular style ever.
No modern designer or sunglasses manufacturer will fail to include variations on the Aviator design in their model ranges.
Ray-Ban Aviators are the originals and the company' like many others, now offers an almost limitless range of designs on the Aviator theme.
There are Aviators with bright flash reflective lenses and multi-coloured frames. The classic style is the thin metal frame, double bridge and inverted teardrop lens.
It's a unisex design that appears to flatter any face and modern variations come with plastic, wood or leather coated frames. Anyone looks cool in Aviators with the right colour frame and the appropriately sized lens.
Street cool frame styles come in many shapes and forms but there are some styles that keep coming back into fashion.
This style makes sunglasses look bigger than they actually are. Oversized lenses are couched in thick lens frames often accompanied by slender thin arms. It makes the lenses look far too big for the frame but with a retro-cool aura that harks back to the glamour of the 1960s. Many frames are made of plastic but there are metal frame versions too and even two-tone combinations.
Deep rim frames
Shortsightedness often requires thick prescription lenses and, bad in the day, these were considered too geeky to attract the fashion conscious. These days deep rim frames can be all the rage and even thin lens models will sport a deep rim frame for a gas punk retro look.
Funky frame shapes
The size and shape of frames and lenses are central to grabbing attention. Bold looking frames like Cat Eyes may grab the limelight but the stylish can do soft and subtle too.
Much depends on what else you want to wear. A slim, understated frame can complement a bold outfit while frames that are 'large and in charge' can bring personality to the most toned down outfit.
Colour is the key
Choosing the right colour frame s the key to making a fashion statement. Multicoloured frames are a big favourite, with a growing trend for lens and frame in contrasting colours.
Looking cool in modern sunglasses is often matching the colour to your clothes, accessories or even fingernails. If polka dots or stripes are your thing there will be sunglasses to match.
That extra pop of colour can grab attention and focus admiring eyes in the right places.
Lenses in bright light colours like pink, yellow and purple were once written off as cheesy but no longer. Manufacturers like Oakley and Ray-Ban now offer an endless array of lens tints from the delicate like pink, peach and jade to ruby red, bright turquoise and even ultramarine.
Many urban cool lens shades are coloured to match different skin tones or to display a cool mood. Buyers need to remember that vision varies with lens colour so different shades are often needed for different situations.
Sunglasses are a great fashion accessory but wearers shouldn't forget that their main function is still to protect the eyes. It makes sense to wear sunglasses that provide protection and looking good.
Potential health hazards to consider when choosing urban cool sunglasses are:
UV (Ultraviolet) ligh
This is the radiation associated with sunlight. UV light can contribute to cataracts and cornea damage. Most of the harmful UV light from the sun is filtered out by the atmosphere but the 10% that gets through still needs to be filtered out by using sunglasses.
Shades for all seasons
We associate sunglasses with summer, but eyes can need protection at other times of the year. Snow can reflect up to 80% of the UV rays and even result in snow blindness. Wearing sunglasses not only prevent this thy will also protect the eyes from dust, debris or sand that can irritate the eyes.
Dark lenses don't protect
It's important to choose sunglasses with good lenses. Dark lenses do not block UV light so choose lenses that are certified to block 100% of both UVA and UVB light.