The impact of Ultra Violet (UV) light on our bodies is well understood worldwide. Less understood, but rapidly gaining attention, is the effect that harmful blue light can have on our eyes.
Harmful blue light, also known as High Energy Visible (HEV) light, is at the far end of the visible spectrum, close to UV light. Present both indoors and outdoors, harmful blue light is emitted by digital devices, Light Emitting Diodes (LEDs) and metal halide lamps, although its primary source is the sun.
According to John Ligas, Transitions Optical’s Vice President, R&D, blue light is often associated exclusively with electronic devices and screens, however the sun is the single largest source of blue light, scattering it through the atmosphere.
“Depending on the time of day, a majority of outdoor visible light you receive is blue light, which explains why the sky itself is blue,” says Mr. Ligas.
Transitions adaptive lenses filter blue light both inside and outdoors
The Role of Light in Human Development
Light plays a critical role in processing sensory information to enable visual perception, and is, therefore, essential to ocular growth and a major environmental factor in human development.
But what risks does exposure to UV and harmful blue light pose – and what can be done to minimise or mitigate these risks?
Risks of Exposure
Our eyes and skin are the only parts of our bodies directly exposed to the sun’s benefits and hazards.
Over time, as we age, the damage caused by the sun’s rays accumulates, and now that we are living longer than ever before, this damage is becoming increasingly significant.
In the case of UV light, both long and short waves penetrate the atmosphere freely, playing a key role in advancing more severe health conditions. UV radiation is well established as a major cause of premature ageing, as well as eyelid malignancies, photokeratis, climatic droplet keratopathy, pterygium and cortical cataract.
While the human eye was meant to receive a portion of blue light, there is also a growing body of evidence to indicate that increased exposure can have a negative impact. Higher in energy than other wavelengths in the visible spectrum, harmful blue light scatters more, creating haze and glare, interfering with vision, causing eye fatigue and reducing contrast sensitivity.
Depending on the time of day, the majority of outdoor visible light that people receive is blue, which is why they squint and turn away from glare. While physiological structures around the eye provide some protection, and the pupil constricts to decrease the amount of entering light, nonetheless the yellow pigments in the macula absorb some of the light, and there is a natural yellowing of the lens as we age.
Minimising and Mitigating the Risks
Despite well-documented evidence that both children and adults spend an ever-increasing number of hours each day indoors using digital devices, our population continues to be active. From cycling to fishing, running to golf, people around the world spend a great deal of time pursuing outdoor interests – and therefore exposing themselves to the sun – often for prolonged periods.
Of course different activities require different levels of eyewear protection and so it is important to recommend the most appropriate eyewear to suit individual customer’s needs. A person who rides their bike to work, but spends all day in an office, for example, needs eyewear protection that differs from someone who drives a bus or works in construction.
Photochromic lenses offer a range of options to suit all lifestyles and are highly efficient when it comes to protecting against glare, automatically adjusting to the amount of outdoor light, whether overcast, in shadow or in bright sunlight.
Because they darken in various lighting conditions, these lenses also help the visual system to adapt, without compromising visual performance or comfort.
Transitions adaptive lenses filter blue light both inside and outdoors. Dark outside when sunlight is bright and intense, they providing protection from UV and harmful blue light. When indoors, the photochromic molecules still absorb some light without compromising clarity of vision.
Transitions has a range of adaptive lenses to suit different lifestyles.
Transitions Signature VII lenses block at least 20 per cent of harmful blue light indoors – up to two times more than standard clear lenses – and more than 85 per cent outdoors. Because they are completely clear indoors and darken outdoors, they are ideal for people who spend equal amounts of time indoors and out.
Transitions XTRActive block at least 34 per cent of harmful blue light indoors and 88–95 per cent outdoors. These lenses are the darkest everyday lenses available in the Transitions range, and even darken behind a car windscreen.
According to Mr. Ligas, Transitions lenses provide “optimal protection and superior health benefits” while also protecting against eye strain and eye fatigue.
“Transitions lenses have always blocked a percentage of blue light indoors because the photochromic molecules in the unactivated indoor state still absorb some light without compromising indoor vision clarity,” said Mr Ligas.
“Because we can control the structure of the photochromic molecules, we can – in turn – provide the benefit of blue light blocking while the lenses are still seen as clear.”
Eyes on Ross Tippett
Ross Tippett is a physiotherapist and senior coach at Adelaide Running Crew. An avid runner, who also enjoys water skiing and football, he is no stranger to changing light conditions.
Mr. Tippett has been wearing Transitions XTRActive lenses for 15 years. Fitted with a multifocal prescription, he said he wears them “every day, everywhere, from when I’m driving and cycling, all the way through to reading, working and running. They only come off when I shower and sleep.”
Mr. Tippett said a significant advantage of these lenses is that he only needs one pair of glasses. “I spend a fair chunk of my day indoors consulting patients or writing reports at the computer. When I’m not at the office, I run three times a week with my fellow members of the Adelaide Running Crew and I coach a running team, so during this time, I’m outdoors and working in changing light conditions. Previously I had to carry around one pair of sunglasses and one pair of reading glasses, which was really inconvenient as I would have to interchange them quite regularly. Now I have one pair of lenses that do it all for me.
“Instead of being apprehensive about twilight running sessions or attending twilight football games, which were always such a hassle, I feel more motivated than ever to get out there and experience all that life has to offer,” said Mr. Tippett. He said knowing that Transitions lenses also protect against blue light was important, given that he spends so many hours each day in sunlight or in front of a computer.