Risks Associated with High-Energy Visible Blue Light from Devices

In the span of a decade, technology has made a seismic impact on our daily life, starting a new digital era. Computer screens, smartphones and tablets are no longer just work tools, but constant links to ever expanding spaces of virtual knowledge, entertainment and financial assets¹. With the increasing use of digital displays, new concerns arise about the effects of this lighting technology on the eye’s health. The LED light used to illuminate the screens emits high-energy blue light which has been linked to visual symptoms categorized by eye doctors as digital eye strain or computer vision syndrome. It is helpful to review the nature of blue light and how it can it be detrimental to our eye health.

Blue light is naturally emitted by the sun and is the high energy portion of the visible light spectrum comprised between 400 and 500 nm, close to the ultra-violet region.

The blue portion of the sunlight’s spectrum is the most intense in the morning, its intensity diminishes during the day, unlike man-made LED lighting and displays, which are more and more abundant around us and retain the same intensity day and night. The absorption of some natural blue light, at around 460 nm, is essential for our wellbeing. This blue light in the morning helps us to wake up, get alert, trigger our memory, temper our mood, while the decreasing effect of the sunlight along the day leads to the renewed production of melatonin, the sleep hormone, at night ^2-4; in other words, lower energy natural blue light is connected to the good functioning of our circadian rhythm. However too much exposure to blue light, especially high-energy blue light through overuse of digital technology, screens, smartphones and tablets for extended time can promote a desynchronization of the circadian rhythm and potential health risks, such as persistent fatigue, poor appetite, sleep disorders including chronic insomnia, mood disorders such as depression, reduced day time cognitive functions and performances, and negatively impact the overall wellbeing of digital device users^5-9. Studies on adolescents who use digital technology at night confirm the potential stress on general health caused by the potential misalignment of the circadian rhythm in adolescents, whose bodies are already undergoing hormonal changes. These include changes in normal melatonin secretion which can cause increased sensitivity to external sleep perturbators¹⁰. Further study is needed are currently underway.

Other research studies have shown the damaging effects of blue light at 415-455 nm on retinal cells through in vitro studies of animal cells. While the cornea and the lens of the eye filter out most ultraviolet light, high energy blue light penetrates the lens to reach the retina. Studies show that during the normal visual cycle a light-sensitive molecule of rod and cone photoreceptors, the 11-cis-retinal, is isomerized into all‑trans‑retinal at 445 nm ^11-13, which is actually cytotoxic to the retinal cells until it is transformed back, in the normal visual process, to cis-retinal via an enzymatic reaction. By-products to this reaction triggered by light form at each step and lead to a mixture of molecules, precursors of lipofuscin, a yellow-brown pigment associated with age-related macular degeneration along with potentially toxic reactive oxidative species ROS. Thus, the photoexcitation of these molecules of retinal (cis and trans), leads through successive reactions to lipofuscin precursors and other potential toxic by-products which can alter the physiology of retinal cells, cause cell death through apoptosis, and potentially lead to macular degeneration^14-16. Although the full pathophysiology of macular degeneration is not full elucidated and is felt my most researchers to be multifactorial including age, nutrition and other individual health issues, excess exposure to high energy blue light is postulated to play a role and appropriate protection seems prudent.

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