The truth about blue light

One of the most frequently talked about topics in the eyewear industry is currently blue light and blue light blocking lenses.

This article focuses on blue light and the products being offered which have been designed to reduce exposure. Although the sun is the main source of blue light, the mounting concerns about exposure to it, particularly HEV (High Energy Visible Light) are largely due to society’s increasing use of smartphones, tablets and computer screens, all of which emit HEV light.

These potentially harmful high-energy visible rays also are emitted by modern LED light bulbs and other high-efficiency Indoor lighting.  Blue light from the sun can damage the retina and at-risk groups should be protected including those with a family history of AMD, smokers, and people who are obese.

So What is Blue Light?

Firstly, there is no standard definition of “blue light” but this description may help:

Visible light consists of a spectrum of individual light rays, each with its own colour and energy level.  This energy is determined by the wavelength of the individual light rays. The shorter the wavelength, the more energy a specific light ray has, and vice versa. Wavelengths are specified in tiny units of length called nanometers (nm). Blue light is that portion of the visible light spectrum that has more energy than any other rays of visible light. In fact, the highest energy (shortest wavelength) blue light rays have nearly as much energy as invisible UV rays that have been shown to be damaging to the eyes.

Blue light (like all types of visible light) can penetrate deeper into the eye than invisible UV rays. In other words, the cornea and lens of the eye are exposed to UV, but these rays pretty much stop there. Blue light, on the other hand, can pass through both the cornea and lens and reach the light-sensitive retina in the back of the eye. Because of its high energy and ability to penetrate deep into the eye, blue light has the potential to cause unwanted changes in the retina over time.

In fact, some researchers believe too much exposure to blue light over the course of a person’s lifetime may increase the risk of conditions like macular degeneration. In particular, light on the high-energy end of the blue light spectrum (sometimes referred to as “violet-blue” light)—appears to have the greatest potential for causing retina damage. Also, not all wavelengths of visible light come to a perfect focus inside the eye. In particular, short-wavelength blue light tends to be slightly defocused compared with other visible light.
This can create a violet-blue “blur circle” that contributes to a phenomenon called chromatic aberration.

Chromatic aberration especially affects visual quality and comfort when viewing print on computer screens and other digital displays, and is believed to be a factor in eye strain that’s common among users of these devices.

The Good News About Blue Light

Some blue light—particularly visible rays on the lower-energy end of the blue light spectrum—actually are good for you! The proper amount and timing of exposure to blue light with wavelengths ranging from 460 nm to 500 nm are very important for regulating our biological clock (circadian rhythm) which influences our sleep/wake cycle and general wellbeing. Exposure to this lower-energy blue light during the day releases hormones that help us feel alert and focused. But too much exposure to these rays later in the evening can suppress hormones that help us achieve restful sleep—resulting in drowsiness and lack of focus during the following day from blue light-induced sleep disturbances.

So How Much Digital Screen Time Do Australians Consume?

Prior to the first release of the Apple iPhone in 2007, the world had no cause to consider digital devices a necessity. Statistical data shows that the use of smartphones in Australia reached over 16.5 million users in 2017 with a projected 19.27 million users expected by 2022. In 2017 adults spent an average of 5.5 hours per day on their digital devices, 3.14 hours of which were on mobile devices. 94% of Australian teenagers, 67% of primary school-aged students and 36% of pre-schoolers have their own mobile screen-based device.  Australian children average 4.6 hours a weekday and 4.5 hours on a weekend day on their screens. For parents the average reported daily use on a weekday is 5.8 hours and 5.3 on a weekend day – with the average total weekly usage of 39.4 hours.

Blue Light Filtration

Currently, there are no studies that definitively link blue light exposure with the development of macular degeneration or other serious eye diseases. However, given the growing body of laboratory research that shows blue light can cause damage to ocular tissues, there is legitimate concern about the potential risks posed by cumulative exposure to the high levels of blue light contained in sunlight. Also, there is reasonable concern that additional exposure to significant levels of blue light from digital devices — in addition to increasing the risk of eye strain related to chromatic aberration and the potential for circadian rhythm alteration — may pose incremental risks to eye health, and that it may take several decades before we fully understand the seriousness of these risks. In light of current research on the effects (and potential effects) of blue light on the eye, the following guidelines may help – subject of course to the opinion of the
Eye Care Professional.

Sunglasses. Sunglasses. SUNGLASSES!

With so much talk these days about the potential risks that digital devices pose to the eyes, it’s easy to forget that the sun is BY FAR a more potent source of blue light exposure for most people. Common sense blue light filtration begins with quality sunglasses that significantly reduce the transmittance of HEV blue light.

Children 

Given that kids spend significant time in sunlight outdoors and are using digital devices earlier and more extensively than ever before, today’s young children will have a greater cumulative lifetime exposure to HEV blue light than their older siblings or their parents. For this reason, and given the current lack of strong clinical evidence regarding the potential long-term effects of decades of increased blue light exposure, it seems prudent to get blue light filtration for all children. In particular, sunglasses or photochromic lenses should be worn outdoors to reduce daily HEV blue light exposure from sunlight.

Consider photochromic lenses 

Light-sensitive photochromic lenses are the most convenient and affordable way to ensure patients have a clear and comfortable vision in all light conditions. Modern photochromic lenses can filter up to twice as much HEV blue light as standard clear plastic or polycarbonate lenses indoors and more than 80 per cent blue light outdoors.

High-risk People

Lenses that filter blue light for people with a higher-than-normal risk of macular degeneration may be prescribed depending on the professional opinion of the eye care practitioner. These high-risk individuals may include people with a family history of AMD and those who spend long hours outdoors or using computers and other digital devices. People who have undergone cataract surgery also may be more susceptible to blue light hazards, depending on the light absorptive characteristics of the intraocular lens (IOL) used during their procedure.

Want to know more?

It is important to get to know what products are available to optimise your vision. Talk to your optometrist to find out more.

 This article has been compiled by Finola Carey ODMA CEO with assistance from Ulli Hentschel – Hoya Lens Australia.