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WHY SO BLUE?

Let’s talk about blue light




The word is out. There is certainly an increased awareness regarding blue light exposure and the potential risks that it might pose. With information just a click away on the internet, there are many sources that may give you contradicting and confusing facts. So, place your trust in your local optometrist and their highly trained staff to help you with the most current and relevant information possible.

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What is blue light? HEV (high energy visible) blue light is at

the high-energy end of the visible light spectrum, consisting of light rays with wavelengths ranging from 380 to 500 nm. We are all exposed to blue light from varying sources including the increased use of screens of all types. With the advent of online learning, remote work, and an increase in online-shopping patients of all ages are experiencing the effects of excessive screen time. This increased exposure to electronics may potentially have effects on our eyes therefore visual and physical discomfort may ensue. Additionally, the residential and commercial shift from incandescent lighting to LED and other more energy-efficient light sources is another source of increased blue light exposure.


While there is still a tremendous amount of research being done to determine the long term effects of blue light exposure, we do know a bit about the short term effects and visual discomfort that goes along with the increase in digital device use. The Vision Council defines digital eye strain as "physical discomfort after screen use for longer than two hours at a time." One factor that contributes to digital eye strain is chromatic aberration, which is the production of a defocused color fringe around text or other objects on a digital display. All eyes have some degree of chromatic aberration, even if vision is fully corrected with prescription eyewear. The human eye is most sensitive to visible light of wavelength 555 nm (green light). When this wavelength is perfectly focused on the retina, HEV blue light is defocused at a point in front of the retina. This can create a violet-blue fringe around objects that can affect visual quality and comfort. The more blue light entering the eye, the more apparent chromatic aberration will be. Wearing eyeglass lenses that filter HEV blue light may reduce the visibility of this blur circle, increasing visual comfort and potentially decreasing symptoms of digital eye strain attributable to chromatic aberration.


Who needs blue light protection the most? Let’s consider the children first, as protection is most important in young eyes. The concern for children is the cumulative effect of photochemical damage starting at a young age. From infancy to approximately age 10 the eyes are more at risk because more than 65 % of blue light can pass through and reach the retina. More HEV blue light reaches their retina because their crystalline lenses haven’t yet become pigmented yellow to absorb some of the blue light. This increases children’s risk of suffering from long term effects of this blue light exposure.


The most well documented effects of blue light are on our circadian rhythm. Although blue absorbed from sunlight can be beneficial by promoting alertness during the day it can disrupt the nighttime sleep cycle. Repeated sleep disruption reportedly increases the risk of Type 2 diabetes, lowers the immune system, and can increase the risk of heart disease. Artificial digital blue light exposure too close to bedtime activates melanopsin which disrupts sleep cycles by tricking the brain into thinking it’s daytime.

One thing is certain: People are exposed to significantly more blue light today, from multiple sources, than ever before. Therefore, until the risks of this exposure are fully understood, it's prudent to take reasonable steps to limit blue light exposure when possible. Please contact our office if you have any questions regarding blue light protection or to schedule your appointment for an exam, 407-801-2477.


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