Blue Light (High-Energy Visible) and Blue Light Blocking Glasses

 The eye’s cornea and lens cannot filter or deflect Blue Light.

Photochemically-induced retinal injury is caused by the absorption of light by photoreceptors in the retina. Photoreceptors such as rod cells, cone cells & photosensitive ganglion cells convert light into electrical signals in the eye. Normally, when light hits a photoreceptor, the cell bleaches and becomes ineffectual until it has recovered through a metabolic process called Wald’s visual cycle. This visual cycle is the biological process that converts photons, such as electromagnetic radiation (UV light & Blue Light) into electrical signals in the retina.

When the retina is constantly and repetitively subjected to the presence and absorption of Blue Light, at a wavelength 400 – 500 nm, rod cells & cone cells become unbleached and responsive again to light before they are ready.

A few minutes of exposure to Blue Light at 408nm is enough to cause permanent death of photoreceptors and lesions of the retinal pigment epithelium.

Blue Light, Eye & Vision Damage

 

Now let’s compare wavelengths…

    • Blue Light (HEV) versus Ultra Violet A, B & C
    • UV-C (100 nanometres to 280 nanometres)
    • UV-B (280 nanometres to 315 nanometres)
    • UV-A (315 nanometres to 400 nanometres)
    • Blue Light (400 nanometers to 500 nanometres)

What does this mean?

At a wavelength between 400 – 500 nm, Blue Light passes through the cornea and lens and reaches the retina.

 

What are some known side effects of exposure to Blue Light?

    • Cataract formation (also caused by long-term exposure to UV light)
    • Age-related Macular Degeneration, the leading cause of low vision & complete vision loss
    • Night Blindness (also caused by lack of vitamin A)
    • Computer Vision Syndrome
    • Sleep deprivation/insomnia
    • Depression
    • Immune system suppression
    • Unstable moods/mood swings

Did you know…

    • Children’s eyes absorb more Blue Light than adults, therefore children are at higher risk of sustaining vision impairment from exposure to Blue Light from digital devices

What are some known devices that emit Blue light?

    • LED lights (even in indirect presence, such as lightbulbs)
    • LED screens / TVs
    • Compact fluorescent lights
    • PC/laptop monitors
    • Smartphones/tablets

Studies that can be found linked at the bottom of this page display a link between exposure to blue light at night, such as working the night shift, to types of cancer, diabetes, heart disease, and obesity. We also know that exposure to blue light suppresses the creation of melatonin, a hormone that assists with controlling our circadian rhythms, and there’s some preliminary studies that suggest lower melatonin levels might explain the association with cancer and other diseases.

That’s not all. A Harvard study identified preliminary results that link blue light to diabetes and possibly obesity. The researchers put 10 people on a schedule that gradually shifted the timing of their circadian rhythms similar to what occurs when you look at a screen or mobile phone. The test subjects' blood sugar levels increased, placing them into a pre-diabetic state, and their levels of leptin, a hormone that keeps people feeling full after a meal, went down.

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