Effects of UV on Eye Health: Outdoor Photochromic Lenses

Australia is the land of the great outdoors in which we spend much of the year exposed to UV rays, more so than many countries, especially those with extended winters.

The Cancer Council has done a great job educating the public on the causes of skin cancer and melanoma. Our profession needs to do this to the same extent, by educating patients about the effects of UV on eye health.

When it comes to recommending spectacle lenses for outdoor use, advances in lens technology have given us the ability to provide a more customised solution to the specific needs of our patients.

As an industry we have more products
and solutions than ever before

Let’s look at the lens options.

Photochromic Lenses

Photochromic lenses were first developed by Corning in the late 1960s and popularised by Transitions in the 1990s. Transitions has been the major supplier of photochromic lenses to the industry but increasingly there are new alternatives being provided by the other lens manufacturers.

How do they work?

These lenses are produced by immersing the plastic lens material in a chemical eyebath containing silver halide molecules. The molecules, which are absorbed to a depth of about 150 microns into the material, are transparent to visible light in the absence of UV light. When exposed to UV rays, as in direct sunlight, the molecules undergo a chemical process that causes them to change shape. The new molecular structure absorbs portions of the visible light, causing the lenses to darken. The number of molecules that change shape varies with the intensity of the UV rays.

When you go indoors and where there is no UV light, a different chemical reaction takes place. The absence of the UV radiation causes the molecules to change back to their original shape, resulting in the loss of their light absorbing properties. In both directions, the entire process happens very rapidly.

This process means that photochromic lenses can be offered for a wide range of lens materials and designs.

Photochromic Limitations

Overcast days: Since photochromic molecules are activated by the sun’s ultraviolet radiation which penetrates clouds, photochromic lenses will darken on overcast days as well as sunny days.

Temperature: The photochromic molecules fade back to their clear state by a thermal process; the higher the temperature, the less dark photochromic lenses will be. This thermal effect prevents lenses from achieving true sunglass darkness in very hot weather. Conversely, photochromic lenses will get very dark in cold weather conditions. Once inside, away from the triggering UV light, the cold lenses take longer to regain their transparency than warm lenses.

Car windshields: Photochromic lenses do not work inside a car due to the windscreen blocking out UV rays needed to activate the chemical process, which causes the lens to darken.

Lens manufacturers are modifying photochromatic lenses to overcome these limitations, as you’ll see in the product listings that follow.

Transitions Signature have Chromea7 technology with photochromic molecules that are less heat dependant. This makes them more reactive to UV light so they get darker in more conditions, including bright sun, partial sun, cloud, and everything in between. They also adapt to indirect light, such as light reflected from buildings, cars, and many other surfaces. These lenses are available in grey, brown and graphite green.

Hoya Sensity uses Hoya’s latest lens innovation called Stabilight Technology. This is the company’s answer to light, UV and temperature reactivity. Tested across different climates, regions, altitudes and temperatures, Stabilight Technology provides consistent photochromic performance with UV protection.

PhotoFusion by Carl Zeiss Vision is made in Germany. These lenses are available in a neutral grey tint for accurate colour vision in all lighting conditions. They darken up to 20 per cent faster and lighten indoors up to twice as fast as previous Zeiss photochromic lenses.

ColorMatic lenses by Rodenstock – also made in Germany, are available in pure grey, chocolate brown and racing green. The company also offers ColorMatic IQ Contrast photochromic lenses in contrast-enhancing shades of orange and green.

Transitions XTRActive are suitable for people who are light-sensitive indoors and need a darker lens when driving and outdoors. These lenses have a slight tint indoors to help shield sensitive eyes and be more comfortable when exposed to harsh lighting (fluorescents lights, digital devices). They also can activate behind the windshield of a car and are available in grey, brown and graphite green tints.

Transitions Vantage feature photochromic molecules that not only darken under the influence of UV light but also align at a proper angle in the lens so that they become polarised. These lenses have a slight tint indoors and polarise as they darken outdoors for a greater glare control in bright, reflective conditions. This makes them suitable for people spending a lot of time outdoors or driving.

Sunglass Photochromatic Lenses

Transitions Drivewear, by Transitions Optical and Younger Optics is useful as an outdoor enhanced sunglass lens, as it is designed to accommodate a range of light conditions outside and behind the windshield of a car.

This lens provides superior visual performance, colour and clarity, by combining polarisation to remove glare from the road and the car bonnet and transitions to adjust the colour and tint of the lenses as light conditions change.

When Do You Suggest Photochromic Lenses?

Firstly you need to identify the visual needs of the patient, their degree of light sensitivity and lifestyle. Are they on the go; do they frequently move from indoors to outdoors; do they need the convenience of one pair of spectacles? Examples of this would be busy mums, children, courier drivers, building site workers, cyclists who start cycling early morning and finish in bright sunlight… the list goes on.

Remember though, that one pair of eyewear cannot meet all the challenges of our today’s lifestyles. Polarised prescription sunglasses are still needed for extensive day time driving and high glare conditions.

As an industry we have more products and solutions than ever before to provide the best eye health, visual comfort, and performance.

Jim Papas is an optometrist with extensive experience in contact lenses. A practice partner of eyeclarity, he is an expert in retail, business strategy and brand development. Jim has won multiple awards for customer service and commercial innovation, including the 2015 Australian Retail Innovator of the Year award. His Melton eyeclarity practice won The Melton Business Excellence Award for the best Retail Business for 2016.

I-Venture lens has been designed for all sunglasses, including curved sport frames for athletes. Using digital ray-path technology, it provide a better visual experience, a more natural wide area of clear vision with sharper acuity in all directions of gaze and a superior level of comfort.

I-Venture is available in all lens materials, including clear, polarised, Transitions and DriveWear options to meet all patients’ visual requirements.

Contact: Hastings Optical
(AUS) 02 6584 3577

NuPolar lenses are now available in Gradient and solid tint. NuPolar Gradient delivers consistent matching every time, does not fade, does not require tinting, blocks 100 per cent UV, and has fast turn-around so patients can enjoy their sunwear sooner.

Contact: Younger (AUS) 08 8241 9800

NuPolar lenses block blinding glare and improve contrast, colour, depth perception and overall visual acuity and according to Opticare, perform better than competition in many crucial tests of polarising efficiency, heat stability, film adhesion, colour stability etc. they’re available in multiple colours, styles and materials to fit your patients’ lifestyle.

Contact: Opticare (AUS) 02 9748 8777

Transitions Drivewear is the world’s only lens that changes to three different colours while also darkening and lightening as outdoor conditions change. Combining NuPolar polarisation and Transitions photochromicsthese lenses darken in bright sunlight to 90 per cent tint with a dark brown colour. When overcast, the lens lightens to an olive colour with 63 per cent tint. When driving, the lens changes to a copper colour with approximately 75 per cent tint. The lens is always polarised with 100 per cent UV blockage.

Contact: Transitions (AUS) 08 8241 9800

Tokai 1.76 is thin, light and now available in grind with neutral colour coating (NCC), to reduce glare by reducing all visible wavelengths of light equally. Available in two colours: dark (50 per cent) and light (20 per cent). Additionally available in single vision and multifocal, with tinting to 85 per cent grey and brown, graduated tints and Transitions 7. P-UV Posterior UV coat P-UV is available with Transitions 7 and tinted lenses.

Contact: Tokai Australia (AUS) 07 3012 9422

Conventional self-tinting lenses are made up of a mixture of molecules of different colours, with each molecule reacting differently to UV light causing colour differences during the darkening and fading processes. The new ColorMatic IQ 2 dyes have a unique molecular structure with all molecules a uniform colour. This ensures an unchanging colour tone across the lens during the total darkening phase up to 88 per cent and fading phase to 6 per cent.

Contact: Rodenstock Account Manager

Zeiss outdoor lenses are available in a wide selection of tint colours, from solid to gradient, providing comfort for all light intensities and eye sensitivities. Polarised, these lens options provide strong colour contrast and clear vision, especially in dazzling sunshine and reflections on water or other wet surfaces. With very large lens diameters, variable decentration and flexible base curve selection, these lenses
fit more wrap frames.

From 30 September, these lenses will be customisable with DuraVision mirror to further reduce light intensity and enhance vision and style. Additionally, a DuraVision sun back surface anti-reflective coating will reduce glare reduction with unparalleled clarity, cleanability and toughness.

Contact: Zeiss Account Manager

Available in both single vision and progressive, Stylistic caters to all needs from clear for pure protection to Xperio polarising and Transitions lenses, both in grey, graphite green and brown. The wrap lens, digitally surfaced with W.A.V.E technology, offers protection, contrast and clear vision to the edges.

Patients who want a full, graduated or polarised tint can also choose
an Essilor mirror coating in silver, blue or gold.

Contact: Essilor Account Manager

Zeiss PhotoFusion self-tinting lenses adapt quickly to changing light situations. Indoors, the PhotoFusion
lenses are very clear whereas outside they turn very dark in the sunlight (clear state: 89 per cent absorption, dark state: 8 per cent absorption).

PhotoFusion lenses provide 100 per cent protection against harmful UV rays lenses, their self-tinting performance and show excellent colour consistency for an attractive appearance in any lens state.

Recommended not only for those who love convenience but also for children to protect young eyes against UV rays and glare. Available in either brown or grey tint.

Contact: Zeiss Account Manager