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  • Neda M.Zadeh

Blue Light: what's the verdict?

What is blue light exactly?

The eyes are able to see a narrow band of light frequencies called the visible light spectrum. Blue light is a short wavelength light that has low frequency and high energy, and has always been an essential part of the human visual experience.

Our main source of blue light is sunlight, however the number of indoor man-made sources of blue light is on the rise; including:

  • Fluorescent lighting

  • LED lighting

  • Display screens (smart phones, tablets, computers, flat screen TVs)

Is blue light exposure bad?

Despite the fact that the eye is good at blocking UV rays from reaching the retina, the eye is not very good at blocking blue light, particularly when we are young. Virtually all blue light passes through the cornea and lens and reaches the retina.

Effects of Blue Light

Blue light is not all bad, in fact, it has health benefits. According to Dr. Maturi, a professor at the Indiana University School of Medicine and a clinical spokesperson for the American Academy of Ophthalmology, exposure to blue light via the sun helps prevent nearsightedness, especially in kids. Blue frequencies also help regulate our mood, alertness, memory and cognitive function. It is also important in the regulation of the circadian rhythm, the body’s biological time clock.

Blue light blocks melatonin secretion, which allows us to be alert and awake during the day. Evening-use of digital devices that emit blue light can interfere with our circadian rhythms (biological time clock). Exposure to too much blue light at night through screens and indoor lighting may lead to poor sleep quality, difficulty falling asleep, and daytime fatigue. 

The eye health industry has responded to this matter by creating filters and apps that filter the blue light from screens at appropriate times, without affecting visibility.  Moreover, some lens manufacturers have developed special glare-reducing lenses and coatings to block blue light. 

Other side effects: cumulative exposure to UV light and high-energy blue light over our lifetime also contributes to cataracts and macular degeneration.

Does blue bight cause eye strain?

Yes. Numerous studies agree that blue light causes eye strain, however it is very difficult to quantify exactly what that means as there is no specific measurement of "eyestrain". What we can quantify though, is that computer screens and other digital devices emit significant amounts of blue light and people are spending more and more hours looking at them. The high energy blue light waves scatter more in the eye and is not as easily focused.  This scatter creates “visual noise” that reduces contrast and can contribute to digital eye strain. 

However... most discomfort from screens is actually due to dry eye, as staring at screens causes us to blink 60% less than we usually do. To combat this, we recommend the 20-20-20 rule: every 20 minutes look 20 feet away for 20 seconds to reset your blink-rate and focusing muscles.

Staying Safe

A healthy diet, high in leafy green vegetables and colourful fruits, may help to increase the levels of the protective pigments in the retina and mitigate some damaging effects of blue light.

Good sleep is essential for attention, learning, mood, and general well-being.  The effects of blue light on the sleep cycle may be minimized by:

  • Avoiding bright screens for 2-3 hours before bed time

  • Seeking some outdoor light exposure in the early hours of the day

  • Limiting screen time to no more than two hours per day for children aged 5-18, one hour per day for children aged 2-5 and avoiding it completely for children under 2 years of age.

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