Handling the Blues

By Mark Mattison-Shupnick, ABOM

Americans on average spend over half their waking hours in front of digital screens such as computers, smart phones, tablets and televisions. Some of these devices emit strong blue light, which scatters easily, can reduce contrast and add to eye fatigue or digital eyestrain resulting from today's popular electronic gadgets. SeeCoat Blue is the first in a new category of functional anti-reflective coatings that reduce blue light. This can enhance contrast and help reduce digital eyestrain.

EYESTRAIN AND DIGITAL DEVICES

According to "Digital Differences" (Pew Internet Study, April 2012, Kathryn Zickuhr, Aaron Smith), 88 percent of American adults have a cell phone, and tablets have grown to 19 percent. Moreover, about six in 10 adults (63 percent) go online wirelessly with any one of the devices shown in the gadget ownership graph. You know this is true from that person who almost walked into you while they were texting. In fact, if you look up "digital eyestrain" on the Web, there's a long list of reports and recommendations.

We've also had a number of CE courses about the changing vision demands of digital devices, the resulting eye fatigue experienced by users and possible new lens opportunities. But a new issue that contributes to eye fatigue is addressed here, i.e., the effect of blue light and its scattering in addition to viewing distance and font size.

"Digital eyestrain is not limited to adults or the workplace. Children are also at risk for eyestrain due to growing use of digital devices. Children today have more digital tools at their disposal than ever before—tablets, smart phones, e-readers, handheld video games and computers. Whatever happened to playing outside? Somehow 'Angry Birds' usurped hide-and-seek because children and teenagers (ages 8 to 18) are spending more than 7.5 hours a day consuming electronic media," according to a study by the Kaiser Family Foundation. "This overuse can cause digital eyestrain, a medical issue with serious symptoms that can affect learning and work productivity. Symptoms of digital eyestrain, or computer vision syndrome, include blurry vision, difficulty focusing, dry and irritated eyes, headaches, neck pain and back pain. Digital eyestrain is now the number one computer-related complaint in the U.S.— ahead of carpal tunnel syndrome." (Source: VSPblog.com)

Why? A paper published last year by Rosenfield, et al, titled "Font Size and Viewing Distance of Handheld Smart Phones" (Optom Vis Sci 2011; 88:795-797) found that "the mean font size for both conditions (viewing a text message or viewing an Inter-net page) was comparable with newspaper print, although some subjects viewed text that was considerably smaller. However, the mean working distances were closer than the typical near working distance of 40 cm for adults when viewing hard copy text. These close distances place increased demands on both accommodation and vergence, which could exacerbate symptoms. Practitioners need to consider the closer distances adopted while viewing material on smart phones when examining patients and prescribing refractive corrections for use at near, as well as when treating patients presenting with asthenopia associated with near work."

WHAT CAN WE DO?

First make patients aware of the issue with digital eyestrain, then describe/prescribe the right eyewear that can help. Consider the number of hours spent on a mobile, tablet or computer and determine the right lens design that can make a difference. Consider a prescription tuned to the right working distance; in single vision consider visual fatigue lenses or in multifocals, one of the many computer progressives. Finish the lenses by choosing the right material (100 percent UV absorbing) and the right AR coating.

Today's major influencers on clear and healthy vision are time in the sun, lighting, vision tasks, time spent online and the electronics used. Customers are making the connection between UV protection for both their skin and their eyes. However, awareness of the hazards of blue light radiation is less well-known.

THE SCIENCE OF BLUE LIGHT AND ITS EFFECTS

Blue light is part of the visible spectrum, the wavelengths perceived as the colors violet-blue to light blue or the wavelengths from about 380 to about 500 nm (Fig. 1). There are three important blue light concerns: 1. Violet and blue are the shortest, highest energy visible wavelengths and are scattered easily creating haze that can reduce contrast and affect the sharpness and clarity of what you see. 2. High-energy blue light can cause retinal damage and finally, 3. Many of the newest electronic devices emit significant blue light. Absorbing the "blue" or high-energy visible wavelengths can improve the clarity of what's seen and add protection as well. Here's the technology behind the effects.

Light scattering haze is wavelength selective, i.e., the shorter blue wavelengths are scattered more than the longer red wavelengths, which are scattered less. This kind of scattering affects visual contrast and is a key component of acu ity at distance and near. For example, a brown bird against a blue sky (higher contrast) is easier to follow than that same bird against a pile of fall leaves where all the colors seem the same. A lack of contrast makes objects much more difficult to identify.

The short wavelengths are easily scattered (bent in all directions) both by the atmosphere and in the human eye. For example, when the particles in the atmosphere (dust, moisture) are smaller than the blue light waves, Rayleigh's Effect scatters the blue light. A blue sky or a blue ocean is an effect of the shorter blue wavelengths being scattered more than the other colors. A large pupil or opacities in the fluid of the eyes can also create glare that produces "hazier" vision, a decrease in the quality of vision. This results in a loss of contrast, and any presence of blue light adds to scatter and the formation of glare. The result can contribute to eyestrain and asthenopia (eye fatigue).

High-energy visible or HEV blue light, while the shortest of the visible light wavelengths, possess the highest energy. These wavelengths have been shown to cause photochemical injury to the retina. The Beaver Dam Eye Study showed that those who had high levels of sun exposure during their teenage years and throughout their 30s had an increased risk of developing the early changes that result in age-related macular degeneration (AMD).

Protective antioxidant pigments in the mac-ula are lost as we age, possibly allowing for greater injury from oxygen free radicals produced. HEV, when accumulated over a lifetime, has been demonstrated as powerful enough to injure human cells, mainly through the production of oxygen free radicals (source: 20/20 CE course "From Correction to Prevention"). This is called the blue light hazard and the International Standards Organization (ISO) has described a hazard function for the retina (Fig. 3) showing the wavelengths that are most concerning. These wave-lengths have been implicated in photo reti-nopathy and AMD.

Blue light emitting electronics today can add to the scatter of images seen as well as be evaluated using the ISO standard. Look at the two graphs (Fig. 4). Each depicts the emissions by color and wavelength of a variety of displays, from a standard computer monitor to popular tablet screens (source: Nikon). In each case, any higher blue light radiance will contribute to various levels of glare depending on pupil size, distance from the eye and scatter internally in the eye.

 

GOT THE BLUES?

The question is what can be done about the blue light from the LEDs, tablets and the sun to which we're exposed every day? Sun lenses always reduce the blue wavelengths, especially when the filter (lens) color is amber, brown and green or are the newer lens products that are formulated especially to absorb HEV/blue light. However, these lenses all require significant tint or polarization to absorb the HEV blue. That makes the lenses perfect for outdoors during the day.

Indoors in low light and at night, clear lenses are required. But there hasn't been a product that addresses all the effects of blue light without significant absorption (a noticeable tint color like yellow). And AR has been formulated to pass all wavelengths to ensure the highest lens clarity. This includes ultra-violet (UV) so photochromics work their best. There are unmet needs to improve the clarity of what you see, reduce the scatter when using electronics and reduce the blue wavelengths reaching the eye. Nikon SeeCoat Blue can enhance contrast by reducing the blur from scatter and add to eye protection.

HOW SEECOAT BLUE WORKS

Nikon SeeCoat Blue is a unique AR, applied to prescription and plano lenses to reflect a portion of the blue wavelengths hitting the lens. This prevents all the blue from passing through the lens to the eye and then the retina. Fig. 5 compares SeeCoat Blue to a premium AR lens and a tint. Modern AR lenses pass virtually all blue light through the lens. This new AR lens reduces blue transmittance in the range from about 410 nm to about 500 nm while transmitting almost all the light at 550 nm, the eye's most sensitive wavelength. Using tints can also reduce blue light transmission but significantly changes the color of the lens and the color of the world seen. SeeCoat Blue reduces blue wavelengths by reflection. In the reflectance graph (Fig. 6), reflectance of blue at 450 nm is just over 10 percent as compared to a premium AR at less than 1 percent at the same wavelength. Ten percent is the total reflectance for the lens or about half that per surface (front and back).

Why 450 nm? The ISO blue light hazard function peaks at 435 to 440 nm, while LED bulbs and various other devices also peak at 440 to 455 nm. Therefore reduction at these wavelengths is the most efficient to reduce the potential effects of blue light.

Why 10 percent? The percent of blue light reflection seems small but is the result of a variety of vision testing at Nikon while balancing the aesthetic requirements of the lens. Using contrast testing as well as a variety of monitors and LCD screens under a variety of lighting conditions, 30 subjects were tested for contrast sensitivity and asked to read text. For contrast, test subjects were asked to choose the least defined horizontal contrast bars they could see (eleven charts of varied contrast in 4.4, 8.7 and 17.4 cpd or cycles per degree scales each). When considering reading and contrast enhancement testing, the best results required a 10 percent reduction of blue light. Efficiently reducing the blue light scatter improved contrast, and that was a benefit the test participant could see. Lastly, any reflection of blue wavelengths is protective up to a point: Our diurnal, circadian rhythms are controlled or influenced by wavelengths between 410 to 430 nm, so we must also be careful not to significantly block this important part of the HEV spectrum.

THE OPPORTUNITY

New technology means opportunities for patients. In this case, this premium AR has been improved with additional patient benefits, reduced scatter and glare for better vision every day whether for far away or when viewing computer, tablet or smart phone screens. This new coating better meets the vision and comfort needs of a fast changing, mobile information-accessing population. It is useful for all age groups and addresses the ECP's mandate to provide clarity and comfort. Finally, it provides some blue light protection since new electronic devices have been shown to emit more blue light wavelengths. After all, blue light is accumulated over a lifetime.

Currently, virtually all the available indoor lens products do not absorb or reflect blue light waves. Its availability is another improvement that can be merchandised to patients. Use this CE to understand the technology and teach patients about the effects of blue light. There are many eye-wear claims out there, and here's one you can demonstrate.

The target patient is a 20-something who is accustomed to digital devices since childhood. It can relieve eye fatigue from long hours at digital screens. For 30s to 50s patients who spend most of their work time at a screen or with a tablet, better glare reduction can help with efficiency and productivity. For the senior with other factors that reduce vision clarity (cloudy media, cataract) this AR can reduce unwanted brightness from TV screens or e-readers, improve contrast and reduce blue light transmission for increased comfort. Again, all benefit from premium AR; consider AR with other improvements by patient.

DEMONSTRATIONS

Demonstrations often make the difference to patients and gets them to say "yes." Show patients the difference in vision with and without See Coat Blue AR, especially if they haven't worn AR before. Point out the blue color reflection off the lens as a way that the patient will know they received the product they ordered. I often realize that many patients are not sure they received what they actually ordered since most of what we sell in lenses is invisible.

SeeCoat Blue has a 97.5 percent luminous transmittance, while reducing blue light by 10 percent compared to conventional AR coated lenses. The coating optimizes trans parency, and has the same scratch resistance and anti-static properties that today's ECP has come to expect from premium AR, while being super-hydro and oleophobic. Of course, for the eye health conditions that are affected by blue light, this lens doesn't take away the continued need for good nutrition, exercise and the effects of genetics. Some patients will also notice a yellow color shift initially when putting in their lenses. In fact, this is evidence of blue light reflection. This effect is not noticed after a few minutes. There is no effect on the patient's complexion color. SeeCoat Blue is available through authorized Nikon distributors.

CONCLUSION

Since every eyecare professional has patients who spend over half their waking hours in front of digital screens, the strong emitted blue light scatters easily, reducing contrast and adds to eye fatigue. SeeCoat Blue is a new functional anti-reflective coating that can reduce blue light, improve contrast and reduce eye fatigue with added protection.