It's a typical bright sunny Summers day in the UK (ha!) and you grab your trusty sunglasses when heading out for the day; unfortunately, they're on their last legs so it may be time for a new pair.
You can hardly fail to notice the vast array of lens choice with regard to modern sunglasses these days, tinted, reflective, polarising, photochromic (or photochromatic – same thing). And then there's the style and size of the frame, oooh! and the price! Is that pair of £200 branded pair in your local Specs'R'Us really any better than the £3 pair bought off a Thai beach?
This article aims to help you make an informed choice to choose the correct lenses for your application and explain how light can sometimes make sunglasses an essential requirement.
How Much Should I Pay?
On the face of it, sunglasses can appear simple; two pieces of coloured plastic or glass (lenses) fixed within a metal or plastic frame that sits on your nose and above your ears – what more can there be?
However, many things can be done to those lenses giving differing results and so determining when and how they are used. As you will soon see, there is quite a difference in what your hard earned pennies will buy with regard to sunglasses.
In a nutshell, generally sunglasses should:
Provide protection from bright, intense light.
Provide adequate protection from ultraviolet rays in sunlight
Provide protection from glare
Eliminate certain frequencies of light.
In the case of motorcycle sunglasses, provide adequate protection to the eye from airborne
particles, ie dust, grains of sand, fag ash thown out of a car window, etc., and, more seriously, stones
thrown up from the vehicle in front of you and into your face.
When too much light hits the eyes the natural reaction is for the iris to close to reduce the amount of light entering. When the iris has reached its limit of closure, the next natural thing that happens is that we start to squint. If these two reactions are still inadequate to reduce the light entering the eye, damage to the retina can occur both temporarily and permanently. Skiers can often become 'snow blind' as a result of the sun reflecting off the snow. Good sunglasses prevent light from entering the eyes to avoid damage.
Light reflected from surfaces such as a flat road or smooth water generally is horizontally polarized. This means that, instead of light being scattered in all directions in more usual ways, reflected light generally travels in a more horizontally orientated direction. This creates an annoying and sometimes dangerous intensity of light that we experience as glare. Good sunglasses can completely eliminate this kind of glare using polarisation and UV rays are also blocked.
Some frequencies of light can enhance vision and others can blur your vision – the right colour of your sunglasses allows them to work better in certain situations.
Poor quality sunglasses often forego many of the benefits of more expensive ones. A lack of UV protection increases your exposure to harmful UV rays by allowing them through to an iris that is open wider and so increasing the damage to the retina.
Little or no impact resistance from a lens can be catastrophic should the projectile pierce the lens and enter the eye causing blindness and/or disfigurement.
Buying the right sunglasses for the conditions in which you intend to use them offers maximum performance and protection and prices can range from £30 to several hundred £'s for the major top brands.
Choosing Your New Sunglasses - Page 2