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By Cheryl G. Murphy
What ECPs need to know about the latest lenses for filtering harmful blue light.
The sea of HEV light in our everyday lives is swelling, but thanks to the latest advances in eyewear we are fully prepared to rescue our eyes from technology’s rising tide.
Decades ago, spectacles protecting eyes from ultraviolet light and allowing more light transmittance via anti-reflective treatments seemed like additional perks put on everyday eyewear, but today patients are beginning to realize that eyecare professionals purposefully prescribe these and other specialized features not as perks but as priorities to protect our eyes and bodies from the unseen threats in our environment and to optimize clarity. Throughout the years, there have been numerous studies showcasing the hazards that UV light exposure can impose upon eye health and now recent studies have uncloaked another danger that our eyes are subjected to, that of HEV or High Energy Visible light.
High Energy Visible light is blue light and like the name implies it is visible and ranges in wavelength from about 380 to 500 nanometers. Recent studies have shown that blue-violet light (wavelengths of approximately 380 to approximately 460 nanometers) can cause retinal cell death and contribute to cataract formation. Cumulative blue-violet light exposure can also worsen the risk of retinal damage in people who have macular degeneration. In addition, since blue light in general has a shorter wavelength it scatters easily, thus reducing visual contrast and increasing eye fatigue.
Besides affecting our vision and eye health, blue light exposure at the wrong time of day, namely nighttime, could alter sleep patterns and disrupt our circadian rhythms by suppressing melatonin production. Lower melatonin levels have deep consequences that go beyond just a poor night’s sleep. Studies have shown that repeated disruptions in melatonin production during evening hours may depress a person’s immune system and could increase their risk for acquiring type 2 diabetes, heart disease and cancer.
Advances in modern technology have increased our daily exposure to blue light and harmful blue-violet light, significantly placing our eyes and our bodies at more of a risk now than ever before. Smart phones, TVs and tablets have put the world at our fingertips and allow us to stay connected but with that comes a trade off—in order for electronic displays to display white light they have to emit a lot of blue light.
According to a study conducted by Wood et al in March 2013, the spectral power distribution level for emitted light from the iPad 1 with a white screen at full brightness peaked just above 450 nanometers. That means much of the light that the device gives off is blue light. It has been said that users of electronic devices should decrease the brightness level on the screens of these devices and avoid using them altogether, if possible an hour before bedtime to help reduce their exposure to emitted blue light, but this isn’t enough. Further protection is required, and HEV protective eyewear can fulfill that need.
Energy efficient lightbulbs, also known as compact fluorescent lamps (CFLs), are another invention that society has readily adopted. While these bulbs may use less electricity, they give off more blue and blue-violet light than their incandescent predecessors (which give off more yellow light). Wahnschaffe et al published a study in February 2013 showing that low intensity exposure to blue light emitting lamps at night significantly disrupted melatonin production and increased alertness perception in healthy individuals after only 30 minutes, while yellow light exposure affected melatonin production only minimally. It is ideal for lamps and lights which have an emittance of blue light to not be used in bedrooms and bathrooms which may be used at night. If patients are wearing blue light filtering lenses, this would also help minimize this indoor hazard.
As we adapt to and welcome these new technological advances into our lives, it is important to recognize that these devices alter our daily environments. Just like we try to protect our eyes from UV light outside we now must try to shield ourselves from any negative effects that HEV light could have on us, whether it is from natural or artificial sources.
People who are conscious of the need to reduce their blue light exposure in this technological age are not the only ones to whom blue light filtering lenses should be prescribed. Children under 18, patients post cataract surgery and people with macular degeneration or those with risk factors for the disease are among those who should also be protected from harmful blue-violet light.
Blue-Violet Light and Ultraviolet Light
On the electromagnetic spectrum, the visible light region ranges in wavelengths from approximately 390 to around 780 nanometers. Longer wavelengths are seen as red, shorter wavelengths are seen as blue and violet. Ultraviolet light, though outside of the visible light spectrum, gets its name because it is the light that is closest to visible violet with a wavelength range from 10 to just under 400 nanometers. Through scientific studies we now know that blue-violet light which is also known as High Energy Visible (HEV) light (and sometimes referred to as near-UV) can also pose a threat to eye health.