Why you should wear sunglasses
Good quality sunglasses eliminate solar ultraviolet radiation (UVR), in particular the more damaging UVB radiation. UV rays from sunlight can damage the retina and the lens of the eye. Long term exposure is linked to conditions like cataracts and macular degeneration.
As the eye cannot see UVR, sunglasses have an important function in blocking UVR. Wearing cheap sunglasses with no UV filters poses an even greater danger than wearing none at all because the pupils will dilate allowing more harmful rays into the eye. Good quality sunglasses filter out both UVA and UVB rays, the latter responsible for causing sunburn and eye tissue damage with prolonged, unprotected exposure.
Good quality sunglasses should have a UV400 rating providing the maximum protection from harmful UVR (and necessary to attain a CE Mark). All the sunglasses and eyewear we sell meet this standard.
Top 10 reasons to wear sunglasses
10 reasons why we should wear sunglasses – starting from a young age
- Sun-related eye damage occurs in the early ages of childhood, particularly between the ages of 3 to 12 years old. UV damage is cumulative and irreversible so it’s very important to protect children’s eyes as early as possible.
- 90 percent of all skin cancers occur above the neck and up to 10 percent of all skin cancers occur on the eyelids. Wearing sunglasses with 100% protection from UVR will not only protect your eyes but also the skin around them.
- Wearing sunglasses can help reduce the frequency and intensity of migraines and bad headaches which can be triggered by bright sunlight. Sunglasses also help to reduce eyestrain and fatigue.
- Cataracts – a clouding of the lens in the eye that reduces vision – are a common ailment, particularly as people age. Cataract surgery is the most common operation carried out by the National Health Service with 400,000 such operations every year. Wearing sunglasses, especially from a young age, will limit the progression of this ailment that can ultimately lead to blindness.
- The sun isn’t the only thing your sunglasses protect you from; it also prevents elements like sand, dust and wind from getting into your eyes. Getting sand in your eyes can be very painful and dangerous. Tiny grains of sand can scratch your eye and can cause permanent damage.
- In the UK alone about 70,000 new cases of age-related macular degeneration (AMD) are reported every year. AMD causes progressive deterioration of the central area of the retina and according to the RNIB, the British charity for the blind, it’s by far the leading cause of blindness in adults in the UK. The simple precaution of wearing sunglasses with a UV filter will help prevent AMD later in life.
- They help keep a youthful appearance – wearing sunglasses will prevent squinting and stop wrinkles and crow’s feet from developing around the eyes.
- Improve your looks. Research carried by Vanessa Brown, a senior lecturer at Nottingham Trent University concluded that sunglasses really do improve your looks because they make your face appear more symmetrical and symmetry is linked to attractiveness.
- UV light can penetrate clouds, so it doesn’t even have to be sunny for your eyes to be at risk. Even when it’s overcast, we can still get up to 90 percent of UV radiation. As our eyes are 10 times more sensitive to UV than our skin, more than any other organ the eye can suffer significant injury from the sun; so be sure to wear sunglasses and skin protection while outside, all times of the year.
- Keeping safe in the car – low sun in the sky or the harsh glare experienced when sun strikes a road after rain can be dangerous and around 3,900 road users a year in the UK alone are injured during incidents where the driver had been dazzled by the sun. Keeping a pair of polarised sunglasses ready to hand in the car will help drivers deal with these driving hazards.
Sunglasses for children
Skiing, walking or climbing at high altitude
What does polarisation mean?
Light is made of particles called photons, which travel through the atmosphere like a wave, zig-zagging back and forth on their way to your eye. Natural, unpolarised light consists of photons bouncing in many directions at once. But as soon as they strike a surface like a road or water they begin vibrating in one direction, usually horizontally. This is called polarised light and it’s this harsh concentrated light – glare – that make it difficult to see and uncomfortable for your eyes.
The polarising filters used in polarised sunglasses absorb these horizontally-vibrating waves that reflect off a surface. That means that only vertically-vibrating waves get through the filter and reach your eye. This greatly reduces the intensity of reflective glare.
Non-polarised sunglasses only reduce the amount of light entering the eye; they don’t block glare. Glare not only makes it difficult and uncomfortable to see but causes eye strain. It also distorts the true colour of objects and makes them harder to distinguish. With polarised sunglasses you get glare-free vision, clear contrasts, more natural colours and reduced eye strain or fatigue. Glare also causes a mirror-effect on water. As a polarised lens will eliminate glare on the water it reduces eye strain and means you will be able to see down below the surface.
Because polarised lenses block glare off a surface they are popular with sailing, boating and watersports enthusiasts, fishing enthusiasts, snow sports enthusiasts, runners, cyclists and drivers.
It’s worth noting that whilst there are many benefits to wearing polarised sunglasses they can reduce the visibility of images produced by liquid crystal displays (LCDs) or light-emitting diode displays (LEDs) found on the instrument panels of aircrafts and dashboards of some cars or in other places such as the digital screens on automatic teller machines (ATMs) and self-service petrol pumps. With polarised lenses, you also may be unable to see your smartphone or GPS device.
We have produced a special video on polarised lenses and their benefits – see our Video section.
The Pros & Cons of lens materials used in eyewear
Here’s an overview of the main types of materials used to make sunglasses and eyewear lenses (including prescription spectacles) and some of their pros & cons.
Glass will always provide the best optical experience as glass refracts light much more efficiently than plastic. It’s the most scratch resistant lens material and blocks UV light. However, glass lenses are heavy (typically sliding down your nose) and can be dangerous: glass lenses are prone to cracking, can shatter with impact or if dropped on a hard surface such as concrete. There are also a limited range of colours available made from glass; for all these reasons glass is not used for sports eyewear.
Most lenses in prescription spectacles made today use a plastic called CR-39 or a very close copy since the material is owned by a US company called PPG. Half as heavy as glass, and far less likely to shatter, the optical quality is nearly as good as glass. Plastic is much lighter than glass, making it more comfortable to wear all day and plastic lenses come in many more colours and larger sizes. It is also much less expensive to use than glass. Hence, since the creation of the plastic lens, it’s become the “default” material for opticians and glass lenses are now much rarer than plastic when it comes to prescription glasses. However, it’s important to recognise that plastic can still shatter and does not provide a high level of impact protection, so it should not be used for most active or shooting sports.
Polycarbonate & Trivex
Polycarbonate and Trivex lenses offer up to 10 times more impact resistance than regular plastic lenses. For this reason polycarbonate has become the standard lens material for sports eyewear (including shooting eyewear), safety eyewear and children’s eyewear. Because they are far less likely to fracture than regular plastic lenses, polycarbonate lenses are also a good choice for rimless eyewear designs where the lenses are attached to the frame with drill mountings. Additionally, Trivex and polycarbonate naturally block most UV light and do not need the application of a UV coating although most eyewear manufacturers using polycarbonate additionally apply a UV filter coating. Historically the image transferred to your eyes with polycarbonate was poorer quality than plastic but with the advent of Class 1 Optical Grade polycarbonate the difference is now much less significant.
As described above, polarised lenses are different to standard sunglass lenses; they have a special film which helps eliminate glare reflected off a surface like a pavement, road, water or snow. Lower priced polarised sunglasses use a multi-layer material called TAC (Triacetate) with the front layer being the polarised film. Even though it’s multi-layer, a TAC lens is very thin usually no more than 1.2mm. Higher grade TAC lenses are available (effectively increasing the thickness of the layers) and these can be 1.6mm thick. With most TAC lenses the polarised film is on the front so it can scratch and eventually lose some of its polarising properties. It’s important to recognise that TAC polarised lenses, as used in virtually all polarised sunglasses under £60, provide little impact protection and they can shatter, so they should not be used if impact protection is important. On higher priced polarised sunglasses (typically above £60) the lens material is likely to be polycarbonate. Here the polarised film is sandwiched between two layers of polycarbonate meaning the polarised film can never wear out. Importantly, a polarised polycarbonate lens also provides impact protection.
Glossary of (optical) terms
AR coatings – Anti-Reflective coatings eliminate reflections on lenses and help reduce glare, improve overall vision and help in low and poor light conditions.
Base curve – The curve of the lens: a base of 4 being relatively flat up to base 10 being a very pronounced curve.
BS EN ISO 12312-1:2013 – Sunglasses and other eyewear imported, manufactured or sold in the European Union must comply with this standard. Sunglasses are categorised as Personal Protective Equipment (PPE) and the relevant European PPE Directive is EU 2016/245. See also CE Mark.
Clip-on – A pair of sunglass lenses that use a clip to attach to spectacles converting them into a sunglass.
Contrast – The difference in brightness between the light and dark parts of an image. A higher contrast lens (such as yellow) provides a much sharper field of vision.
CE Mark – This means the product complies with relevant EU safety, health and environmental requirements; for ‘general purpose sunglasses’ the relevant standard is BS EN ISO 12312-1:2013.
CR39 – A lightweight plastic lens material now universally favoured by opticians to make prescription lenses for spectacles and sunglasses. Limited impact protection.
EN166 / ANSI Z87.1 Standards – European & US (respectively) safety standards that must be met for eyewear to be considered to have projectile impact protection.
G15 – A grey-green lens colour made popular by Ray-Ban and used in their classic aviator sunglass. A good alternative to plain grey.
Glass – Glass lenses provide the best possible visual experience and high scratch resistance, but they are heavier than plastic and polycarbonate lenses and can shatter, so not for use in sports sunglasses.
Interchangeable lenses – Models with interchangeable lenses (also called Multi-Lens sets) have become very popular because they give a choice of different lens colours fitting the same frame. They will typically come with at least 3 different lenses.
Lens colours – Polycarbonate and Trivex lenses can be made in a huge variety of colours. These colours can be used for different light conditions, backgrounds and to highlight different target colours e.g. in archery and shooting.
Lens categories – The lens category number (Cat. 0 to Cat. 4) equates to a percentage of the VLT (Visible Light Transmission) i.e. how much light the lens lets through, as follows:
- Category 0: 80-100% VLT
- Category 1: 46-79% VLT
- Category 2: 18-45% VLT
- Category 3: 8-17% VLT
- Category 4: 3-8% VLT
Macular degeneration – A degenerative disease that causes deterioration of the central portion of the retina known as the macula, resulting in loss of vision and even blindness. Wearing sunglasses (with UV filters) from an early age can help prevent this disease.
Mirror, revo mirror & flash mirror coatings – Mirror and mirror-revo are coatings applied to the front of the lens (usually applied to a base ‘smoke’ lens). The term ‘revo’ applies when the mirror has more than one colour e.g. red-orange. Mostly chosen for cosmetic effect they also limit glare and increase the filtering power – this can block an additional 10 – 60 % of visible light for greater comfort in intense, full-sun conditions. A flash mirror finish is not a full mirror effect but gives a slight reflection.
Over Glasses – Over glasses are purpose deigned to fit over a pair of spectacles providing sunglass lenses. They typically come with polarised lenses. The term OTG (Over The Glass) is used to describe ski and other goggles that will fit over spectacles.
PD Measurement – Pupillary Distance measurement: the distance between the pupils of the eyes, centre to centre, in millimetres. Most people have a PD between 54mm and 74mm. If shown as two numbers, such as 31/31.5, this is the distance from the centre of the nose to each pupil centre. To make prescriptions lenses an optician needs the PD number in additional to normal prescription information.
Photochromic – Lenses that automatically adjust to different light conditions for example going from a light tint in poor/low light to a dark tint in strong sun. The change in tint can take up to 60 seconds. Originally only possibly with glass lenses but now widely available in polycarbonate and Trivex lenses.
Polarised / Polarized lenses – Polarised lenses are different to standard sunglass lenses; they have a special film (either applied to the front of the lens or embedded in the lens) which helps eliminate glare reflected off a surface like a pavement, road, water or snow. Because polarised lenses block glare off a surface they are popular with sailing, boating and watersports enthusiasts, fishing enthusiasts, snow sports enthusiasts, runners, cyclists and drivers.
Polycarbonate – Polycarbonate lenses have very high impact resistance: 5 times more than normal plastic and 20 times more than glass. Lightweight, they also have ‘built in’ UV protection. The lens material favoured by all sports eyewear manufacturers.
RX – Short for prescription.
Smoke lenses – ‘Smoke’ is the lens colour typically used as the base colour when a mirror finish is applied to the lens. It is similar to grey but can have a brown or blue hue.
TR90 / Grilamid (nylon) – A rugged, durable, strong, flexible, lightweight material used in sports eyewear frames. Less prone to breaking in extreme temperatures.
Trivex – Trivex lenses, developed in the United States by PPG Industries, is the main rival to polycarbonate for sports eyewear lenses. Trivex lenses are cast moulded, while polycarbonate lenses are injection moulded and the slower cast moulding process is said to result in superior optics. Trivex is more expensive than polycarbonate but has the edge in terms of being lighter, improved impact resistance and sharper optics.
UV400 – A sunglass that is labelled and / or marked UV400 means they block over 99% of UVR. This rating ensures that all light rays with wavelengths up to 400 nanometres, including both UVA and UVB rays, are blocked out. See also UV filter. To obtain a CE Mark sunglasses must be UV400 rated. Hence the marking on sunglasses is usually: CE UV400
UV Index – The UV index, also known as the Ultraviolet Index, is an international system of measuring ultraviolet solar radiation for a specific day and geographical location. The higher the index, the more intense and dangerous to your health the solar radiation is. When the UV Index reaches 3 or more – even on cloudy days – wearing sunglasses is highly advisable, especially for children.
UV Filter – A lens coating, either applied to the front or embedded in the lens, that filters UV radiation. The UV filter is clear so even clear lenses can provide full UV protection. Trivex and polycarbonate lenses naturally block most UV light and do not need the application of a UV coating. See also UV400.
Visual acuity (VA) – Visual acuity is dependent on optical and neural factors, that is the sharpness of the retinal focus within the eye. For sunglasses and eyewear, the term is often used to describe the clarity of vision of the lenses e.g. ‘exceptional visual acuity’.