StemCell Therapy

While blue light has been blamed for sleep loss, its not the only bad light. Chaoss/Shuttterstock.com

Blue light has gotten a bad rap, getting blamed for loss of sleep and eye damage. Personal electronic devices emit more blue light than any other color. Blue light has a short wavelength, which means that it is high-energy and can damage the delicate tissues of the eye. It can also pass through the eye to the retina, the collection of neurons that converts light into the signals that are the foundation of sight.

Laboratory studies have shown that prolonged exposure to high-intensity blue light damages retinal cells in mice. But, epidemiological studies on real people tell a different story.

As an assistant professor at The Ohio State University College of Optometry, I teach and conduct vision research, including work with retinal eye cells. I also see patients in the colleges teaching clinics. Often, my patients want to know how they can keep their eyes healthy despite looking at a computer screen all day. They often ask about blue-blocking spectacle lenses that they see advertised on the internet.

But when it comes to protecting your vision and keeping your eyes healthy, blue light isnt your biggest concern.

Sunlight has more blue light than your computer. miamgesphotography/Shutterstock.com

One way to think about blue light and potential retinal damage is to consider the Sun. Sunlight is mostly blue light. On a sunny afternoon, its nearly 100,000 times brighter than your computer screen. Yet, few human studies have found any link between sunlight exposure and the development of age-related macular degeneration, a retinal disease that leads to loss of central vision.

If being outside on a sunny afternoon likely doesnt damage the human retina, then neither can your dim-by-comparison tablet. A theoretical study recently reached the same conclusion.

So, why the disconnect between blue lights effects on rodent eyes and human eyes?

Human eyes are different than rodent eyes. We have protective elements, such as macular pigments and the natural blue-blocking ability of the crystalline lens. These structures absorb blue light before it reaches the delicate retina.

That doesnt mean you should throw away those sunglasses; they provide benefits beyond protecting your eyes from the Suns blue light. For example, wearing sunglasses slows down the development of cataracts, which cloud vision.

Just because blue light isnt harming your retina doesnt mean your electronic devices are harmless, or that blue light doesnt affect your eyes. Because of its wavelength, blue light does disrupt healthy sleep physiology. Blue-light-sensitive cells, known asintrinsically photosensitive retinal ganglion cells, or ipRGCs, play a key role here, because they tell the brains master clock how light it is in the environment. That means, when you look at a brightly lit screen, these cells help set your internal clock for daytime-level alertness.

But these cells are sensitive to colors beyond blue because they also receive input from other retinal neurons that are sensitive to the entire color spectrum.

Therefore, eliminating blue light alone doesnt cut it when it comes to improving sleep; you need to dim all colors.

As for your tired eyes after a long day spent staring at your computer another common complaint I hear from my patients blue light isnt solely to blame for that, either. A recent study demonstrated that cutting blue light alone did not improve peoples reported comfort after a long computer session any more than simply dimming the screen.

Many patients want to know if they should buy certain products they have seen advertised to block out blue light. Based on research, the short answer is no.

First, the truth is that any bright light too close to bedtime interferes with sleep.

Mounting evidence suggests that, compared to reading a paperback, screen time before bed increases the time it takes to fall asleep. It also robs you of restorative rapid-eye-movement sleep, dulls focus and diminishes brain activity the next day. Holding your phone close to your eyes with the lights on likely exacerbates the problem.

Second, the products that my patients ask about do not block out much blue light. The leading blue-blocking anti-reflective coating, for example, blocks only about 15% of the blue light that screens emit.

You could get the same reduction just by holding your phone another inch from your face. Try it now and see if you notice a difference. No? Then it shouldnt surprise you that a recent meta-analysis concluded that blue-blocking lenses and coatings have no significant effect on sleep quality, comfort at the computer, or retinal health.

Computers cause eye strain because people dont blink as often when staring at a screen. fizkes/Shutterstock.com

There are ways to make your screen viewing more comfortable and more conducive to sleep.

First, turn off your electronic devices before bed. The American Academy of Pediatrics recommends that bedrooms be screen-free zones for children, but we should all heed this advice. Outside of the bedroom, when you do look at your screens, lower the brightness.

As for eye strain, ensure that you have the appropriate glasses or contact lens prescription. Only an optometrist or ophthalmologist can give you this information.

You also need to take care of the surface of your eyes. We dont just look at our computer screens, we stare at them. In fact, our blink rate plummets from about 12 blinks a minute to six. As a result, tears evaporate off the eyes, and they dont accumulate again until we step away from the screen and start blinking. This causes inflammation on the eyes surface. Thats why your eyes feel dry and tired after a day spent at the computer. I counsel my patients to take two steps to ensure that their eyes stay moist during long computer sessions.

First, follow the 20-20-20 rule. The American Optometric Association defines this rule as taking a 20-second break every 20 minutes to look at something 20 feet in the distance. This will allow your eyes to blink and relax. There are many apps available to help remind you to follow this rule.

Second, use a lubricating eye drop before extended computer use. This tactic will reinforce the bodys natural tears and keep the eyes surface hydrated. But, avoid those get-the-red-out drops. They contain drugs that cause long-term redness and preservatives that may damage the outer layers of the eye. I have found that artificial tears labeled preservative free often work best.

Based on my research, my advice is dont believe the hype about blue light and dont waste your money on products you dont need. Instead, keep screens out of your bedroom and dim them before bedtime and keep your eyes lubricated. And dont forget to blink!

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Phillip Yuhas, Assistant Professor of Optometry, The Ohio State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read more:
Blue light isn't the main source of eye fatigue and sleep loss - it's your computer - The Ohio State University News

This entry was posted on October 15, 2019 at 6:45 am and is filed under Eye Sight & Vision. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed. |