Blue Light Blocking Glasses, Why and How?
Blue light is on the higher energy end of the visible light spectrum (around 400-500nm), approaching ultra-violet light. This means it acts a little differently than the higher wavelength (lower energy) light spectrum. There are really three things to consider when considering blue light blocking glasses.
First, blue light scatters more easily than other colors of light. This is actually why the sky is blue. The blue light we see in the sky is light that has scattered. What this means for our eyes is that the blue light part of an image is a little out of focus relative to the rest of the spectrum (the blue light is actually focusing a little in front of the retina, instead of right on the retina). Blue light blocking glasses can sharpen up images by taking out some of this scattered, unfocused light, leaving a sharper image. The effect of blue light blocking glasses is especially pronounced when viewing electronic devices because most screens are heavily weighted to the blue light spectrum.
Second, blue light has been shown in multiple studies to adversely effect circadian rhythms, and make it harder to sleep. While not affecting your eyes directly, lack of sleep has been linked to conditions ranging from dry eye syndrome to type 2 diabetes. So, blue blocking glasses may again be helpful in allowing the body to more naturally regulate the sleep cycle.
Finally, elevated blue light exposure has been shown in experiments to cause retinal damage that could lead to macular degeneration. However, these experiments involved quite high intensity exposure to blue light sources so it is difficult to confirm that an equivalent effect is present with blue light exposure in everyday life.
Overall, at Portland Eye Care, we believe it is worth it to wear blue light blocking glasses for the benefits of better sleep and sharper, more relaxed vision, especially when using electronic devices or working under LED lights for extended time. We are not sold on the benefits of blue light blocking glasses relative to retinal health, though we will continue to evaluate the research as it is published.
Blue light blocking glasses are produced in a couple of ways. Tinted lens materials can be used with a yellow or amber tint that will block a significant amount of blue light. However, one of the best ways is to incorporate the blue light blocking properties into the anti-reflective coating of the lens. This allows for lenses that still block a significant portion of the blue light spectrum while minimizing the yellow color of the lens.