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Dr. Jim Winnick

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What is blue light, and why should you care?

What is blue light, and why should you care?

Most of us have an understanding that overexposure to ultraviolet (UV) light is bad for our eyes. We’ve learned to shop for sunglasses that have “100% UV Protection”. This is still good advice. However, due to a dramatic increase in our use of electronic devices and energy-efficient lighting, there’s increased concern about our exposure to another part of the visual spectrum... blue light.

Blue light itself is nothing new. It’s been present in natural sunlight and in artificial light in varying concentrations since the beginning of time. It’s actually very close to UV light in the visible light spectrum (Ultraviolet = 10-380 nm, Blue-violet = 380-455 nm). The difference is the level of exposure to blue light that we’re receiving in our modern world. The majority of this increase comes from our growing dependence on electronic devices, and how quickly this trend has occurred. Let’s look at a few dates that we can probably all relate to:

  • Early 1990’s = PDA’s (Personal Digital Assistants) enter the market
  • 1996 = Nokia introduces the first widely accepted PDA/Phone combination (Smartphone)
  • 2003 = Blackberry dominates the Smartphone market
  • 2007 = Apple launches the iPhone
  • 2010 = Apple introduces the iPad

Looking back, who could believe that the iPhone and iPad have been in existence for less than 10 years! Many people couldn’t imagine living without them. Try taking away the smartphone from any of your family members and see what kind of reaction you get. According to the recently released 2016 Digital Eye Strain Report from The Vision Council, “Eyes Overexposed: The Digital Device Dilemma,” 90% of Americans spend at least two hours looking at digital devices each day. One in ten spends at least 75% of their waking hours staring at a screen, and nearly 70% of Americans use two or more devices simultaneously. 67% of people in their 30s spend five or more hours a day on digital devices. Children aren’t much better, with 33% of them using a digital device three or more hours each day. So what does all of this increased exposure to blue light mean for our eyes?

Blue light exposure and its impact on daily visual performance, eye disease and systemic health is becoming universally accepted, both in scientific literature and in the medical community. Here are the three major consequences of blue light overexposure:

  1. Blue light degrades the quality of your vision and strains your eyes. Because blue light bends more than other wavelengths as it transmits through our eyes, it actually focuses in front of our retina (similar to a nearsighted person who can’t see well at distance), causing blurring of images. Shorter wavelength light also scatters more than longer wavelengths (that’s why the sky looks blue to us), creating most of the problems we experience with glare. When our eyes are trying to focus, they are fighting against these two principles, which result in eyestrain, especially when working with LED-illuminated screens and/or in our energy efficient LED & CFL-lighted homes and offices.
  2. Blue light is a major environmental factor contributing to cataracts and retinal disease, including macular degeneration. As we said in the introduction of this article, we’ve known the importance of protecting our eyes from ultraviolet light for years. But, most ultraviolet light is actually absorbed by the corneas and lenses of our eyes before it can reach the back of the eye. Blue light is the highest energy light which actually reaches the retina and damages our macula and central vision. Studies have shown that blue light in the 400-500 nm range is most toxic to our retinal cells. Over many years, this can cause macular degeneration, the leading cause of blindness in the western world.
  3. Exposure to blue light indoors and at night disrupts our sleep cycles (circadian rhythms). There are special light-sensing cells in the back of our eyes that control our sleep-wake cycles. Sunlight, the primary source of blue light, signals the brain to stop the secretion of a hormone called melatonin. This wakes us up and keeps us alert during daylight hours. When the sunlight (and blue light) disappears at night, the eyes trigger the brain to release melatonin, putting us in a restful state and triggering our natural sleep cycles. Exposure to blue light from our electronic devices at night tricks the brain into thinking its daytime. This inhibits the production of melatonin, making it harder to fall asleep and to reach the deeper phases of our sleep cycle. According to the National Center on Sleep Disorders Research, sleep related problems affect between 50 and 70 million Americans of all ages. Sleep disruption has adverse effects on attention, reaction times and mood. It has also been linked to several types of cancer (breast, prostate) obesity and depression, diabetes, heart disease and ADHD symptoms in children. The current recommendation from the Harvard Health Letter is to turn off blue light sources at least three hours before going to bed, or to wear blue-filtering lenses.

The optical industry has taken blue light seriously and has developed a whole new generation of products to protect our eyes from overexposure. Innovative new lenses and coatings have been developed to shield our eyes from the flood of blue-violet light which we now endure every day. These products selectively filter out blue light and thereby protect our eyes against the negative effects outlined in this article. The doctors at Brookside Optometric recommend the addition of Sharper Image TechShield to our patient’s lenses. This unique product combines advanced blue light protection with premium AR (anti-reflective) properties to deflect as much as 80% of the blue light associated with visual strain, while still allowing the body and the eyes to receive the positive benefits of blue light like proper color perception, amplified attention levels, wakefulness and the proper regulation of sleep cycles. To learn more about blue light, and read research articles on the subject, go to www.sharperimagevision.com. Talk to your Brookside Optometric doctor about blue light protection for you and your family members.

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Wednesday, 21 November 2018

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