Not all sunglasses are equal
Better Vision explains what you should know about UV protection, tinting, mirrors, polarised lenses and more, to help you find the right sunglasses for your individual needs.
Sunglasses are more than just a fashion accessory – it’s important that they give your eyes full UV protection. On top of that, your sunglasses should suit your needs, whether you ski, do watersports or simply walk your dog in the park. There are various ways to customise your sunglasses with different types of lenses and coatings. Here’s what you should know before buying yours.
Full UV protection
When it comes to choosing sunglasses, a stylish frame that suits the shape of your face is first priority for many of us. The frame choices and lens options are endless, and it’s easy to lose track of the reason you need to wear sunglasses in the first place – to protect your eyes from harmful ultraviolet radiation (UVR).
UV rays are present all day, every day, in winter and summer, and even when it’s cloudy. Excessive UV exposure can lead to acute eye damage such as photokeratitis (sunburn of the cornea) and eyelid sunburn. It can also cause chronic eye damage such as cataracts and pterygium (a growth that covers the white part of the eye over the cornea).1,2
According to the World Health Organization (WHO), roughly 20% of all cataracts are caused or enhanced by UV radiation. Cataracts cause 48% of blindness, making it the leading cause of blindness worldwide.3
For this reason it’s essential to check whether the sunglasses you own, or the ones you are about to buy offer full UV protection up to 400 nm. It should bear the CE mark (which guarantees that your glasses meet the fundamental safety requirements of the European guidelines), and some glasses may also have a UV400-label. This is usually displayed on the lenses with a sticker or tag, or your sunglasses may come with a product information brochure, but always consult your eye healthcare professional to make sure that your sunglasses offer sufficient protection.
Tip: Many entry-level sunglasses may bear the CE mark and offer adequate UV protection, but these lenses are often produced using inferior technology. Premium sunglass lenses are cut, and not pressed, as this can create streaks, bubbles or enclosures in the lens that may affect your vision and lead to eye fatigue. Such glasses may improve your vision outdoors and in bright light temporarily, but in the long run it can do more harm than good.
If you have vision problems, spectacles and contact lenses may not always be the most comfortable option, especially when you drive or spend time outdoors. Clear lenses won’t reduce annoying glare and bright light, and contact lenses can feel dry and irritating when it’s windy; or even worse, scratchy and sandy at the beach.
Luckily, your corrective prescription doesn’t have to get in the way when you’re lazing next to the pool or hiking in the woods, as prescription sunglasses are available for various lens types to suit your needs. Whether you’re myopic or presbyopic, or you wear progressive, bifocals or varifocal lenses, a reputable eye healthcare professional will be able to assist you in customising sunglass lenses perfectly suited to your prescription. In addition, you can customise prescription sunglasses even further with polarisation filters, specialised coatings, mirrors, and solid or gradient tints.
Tip: When you’re getting prescription sunglasses, give your eye healthcare professional as much detail as possible. Tell them whether you will be using the sunglasses to drive with, what sports and activities you plan to do, and how often you want to wear them. This will help to give you the best individualised lens solution.
Light reflections create glare, an unpleasant blinding effect often experienced around water, wet surfaces or roads. Glare can be potentially dangerous, especially for drivers and those who do outdoor sports such as cyclists, joggers and skiers. Light waves swing in all directions, but when light is reflected from flat surfaces such as wet roads, for example, the light waves align and swing only in one direction (i.e. it becomes polarised). This effect can be used to eliminate glare. Some sunglass lenses contain polarisation filters that don’t allow this reflected (and therefore vertically polarised) light through. Wearing such sunglasses, you will be able to see everything, without the annoying reflections. Polarised sunglasses don’t only improve visual comfort, but may also improve contrast vision and display colours more vividly, making them suitable for many outdoor activities. Polarisation filters are available for most types of prescription sunglasses, so consult your eye healthcare practitioner for more information.
Polarisation filters can drastically reduce uncomfortable glare, improving vision when driving or doing watersports, skiing, cycling or jogging.
Tip: Polarised lenses are not suitable for all situations. You may struggle to see certain LCD displays or the instrument panels in older cars when wearing them. Be sure to tell your eye healthcare professional exactly what you plan to use your polarised sunglasses for before buying them. Also ask to test the lenses in “real-life” situations rather than only inside a practice or store. Take a walk outside, and look at your vehicle’s panel display through the lenses if possible.
The brightly coloured sunglass lenses of the nineties are making a comeback!
Customised and prescription sunglasses can be tailored with lens tints in any colour you can think of, ranging from bright pink to blue, yellow or green. In addition to being fashionable, tinted lenses can also be useful for sports (read more about that below).
Tinted lenses are also available in more conservative hues such as grey or brown, and most colours come in gradient tints – fading from dark into light from the top to the lower half of the lens; or double gradients changing from one colour into another. Such sunglasses are particularly comfortable in situations where top and bottom light conditions are different, making them ideal for driving. A lens that is shaded darker towards the top half will enable drivers to see the road clearly, minimising blinding light, while lighter gradient towards the bottom makes it easier to check instrument panels inside the vehicle.
More about special tints
Some coloured lenses have limitations, and you can’t necessarily wear them for every occasion. You may have read about, or heard your eye healthcare professional refer to “lens categories”. These categories differ from lens to lens, and here’s how it works:
Clear lenses or safety lenses that are not tinted, and are best suited to situations where the wearer needs to see clearly.
Light fashion tints for a unique style that mostly filters low light intensities.
Medium tints to filter medium light intensities. A lot of sunglasses fall in this category, and they generally provide full UV protection (always confirm with your eye healthcare practitioner).
These lenses will block even more visible light than category 2 lenses and are ideal for bright light conditions. Category 3 lenses work well with wrapped frames (ask specifically for wrapped lenses) for sports and water sports.
Category 4 lenses filter 92% or more of visible light. It’s not suitable for driving, and is best for specific applications and extreme conditions such as glacier hiking.
Tip: Not all tinted lenses are suitable for driving, as certain colours may influence your ability to see traffic or signal lights. Colours with light absorption above 25% (category 2 and higher) are not suitable for night driving.
You may have heard of light adaptive, photochromic, self-tinting, or variable tint lenses. These are all terms used to describe clear or slightly tinted lenses that darken in reaction to UV light. Such lenses are particularly comfortable for people with corrective prescriptions, because it’s no longer necessary to constantly switch between prescription spectacles and prescription sunglasses.
Sunglasses only provide visual comfort up to a point, and with constantly changing light you may find that your lenses appear too dark in shady areas or too light in bright sunlight. In situations like these, your natural reaction may be to simply take your sunglasses off, leaving your eyes unprotected.
Photochromic technology has come a long way and smart sun lenses such as ZEISS PhotoFusion X are specifically designed to adjust their colour intensity depending on UV exposure. The lenses are already tinted, but they are activated in bright sunlight, going from dark to darker in a few seconds. In the shade, the lenses will get lighter once again so you can see better, but your eyes will still be protected from harmful UVR. They are also available with polarisation filters for glare reduction and added visual comfort.
Tip: As with some photochromic lenses, AdaptiveSun lenses will become much darker in cold, sunny environments, and may limit visibility in extremely cold weather. They are not suitable for operating open air vehicles such as convertibles, motorcycles, all-terrain vehicles, snowmobiles or engaging in activities such as skiing.
Mirror coatings can be applied to the front of sunglass lenses, and they’re available in a variety of metallic hues. In addition to being fashionable, mirror coatings limit the amount of light entering the lens even further, so they are ideal for activities that involve very bright light. Premium mirror coatings such as ZEISS DuraVision Mirror also repel dirt, so no more sandy lenses when you’re at the beach!
Tip: Mirror coating colours are purely aesthetic, and are applied onto a lens. You don’t have to be concerned about a mirror influencing your vision, however, the lens colour combined with a specific mirror can affect your vision and your eye healthcare professional will be able to advise you on suitable combinations.
With mosts sports, you need to be able to see well to perform well. This can be quite challenging especially for outdoor sports, as bright light, wind, rain and snow can influence your vision. A good pair of sports sunglasses must protect your eyes from the elements, reduce glare, and improve contrast.
If you’re in the market for sports sunglasses, here’s what you can discuss with your eye healthcare practitioner:
Specific colour tints: Functional tints are available for specific sports. Golf sunglasses are often a brown, amber or coppery hue, helping players to see the white ball better on the ground. Target shooters and hunters tend to opt for yellow lens sunglasses for greater contrast, whilst sunglasses with blue lenses may be beneficial for sports where there are yellow elements such as tennis and archery (yellow ball and yellow target).
Wrapped lenses: A lot of modern sports frames are “wrapped”, meaning that they curve around the eyes and head for full coverage, allowing minimal light in through the sides. Not all lenses are suited to wrapped frames, and you may experience visual aberrations with an incorrect lens choice. A special optical correction within the lenses is needed to compensate for the specific optical errors caused by the strong wrap angles. Talk to your eye healthcare practitioner about ZEISS Sports Lenses that provide optimum vision for curved frames.
Impact resistance: For obvious reasons, sports sunglasses should offer at least some degree of impact resistance depending on the sport you intend to use it for. Polycarbonate lenses tend to be the preferred lens material for sports sunglasses.
The crystalline lens in children’s eyes is more transparent than that of an adult eye, allowing UV radiation to pass. On top of that, up to 50% of the total UV we’re exposed to by the time we’re 60 occurs before we turn 20. UV damage is cumulative, and it’s very important for children to start wearing sunglasses and protect their eyes from an early age.4
Most of the customisation options available for adult sunglasses are available for children too. The same UV protection standards also apply to children’s sunglasses, and you should take care in selecting good quality lenses for your child. Speak to your eye healthcare practitioner for more information.
Find a ZEISS optical provider - My Vision Profile - Online Vision Screening
McCarty CA, Taylor HR. A review of the epidemiologic evidence. Linking ultraviolet radiation and cataracts. Dev Ophthalmol. 2002.
Moran, D. J., & Hollows, F. C. (1984). Pterygium and ultraviolet radiation: a positive correlation. British Journal of Ophthalmology. 68(5), 343-346.
Resnikoff, Serge et al. “Global data on visual impairment in the year 2002”Bulletin of the World Health Organization vol. 82,11 (2004): 844-51.
Green AC, Wallingford SC, McBride, P. Childhood exposure to ultraviolet radiation and harmful skin effects: Epidemiological evidence. Prog Biophys Mol Biol. 107(3): 349-355, December 2011.