Blue Light Filters
WHAT IS BLUE LIGHT AND HOW DOES IT AFFECT YOUR EYES?
Blue light is part of the visible light spectrum and is everywhere in our environment. The main source of blue light is sunlight however it can also be emitted from digital screens such as computers, laptops, and phones.
Blue light has the shortest wavelength (ranging from 380 nm to 500 nm) and contains the highest energy. This means that blue light has more potential to cause harm to the eyes than other colours in the visible light spectrum.
The cornea and lens are effective at blocking ultraviolet (UV) rays from reaching the retina, however high energy visible blue light penetrates these structures and reaches the back of the eye.
Long term exposure to blue light may have risks. An example of this is that too much blue light at night can cause sleep problems and daytime fatigue. Blue light can also contribute to digital eye strain. This is because blue light scatters easily, causing light rays to be defocused on the retina. When light is not focused on the back of the eye this can contribute to digital eye strain. Exposure to blue light has also been suggested to increase the risk of developing macular degeneration in certain studies.
RESEARCH ON BLUE LIGHT AND MACULAR DEGENERATION - ARE THEY REALLY LINKED?
The disease process of Age-related Macular Degeneration begins with the accumulation of lipofuscin (photoreceptor waste products) in the retinal pigmented epithelial (RPE) cells at the back of the eye. This occurs due to our normal aging process. In the presence of light, lipofuscin forms reactive oxidative chemicals which are toxic and can cause damage to the RPE cells. Once these cells are damaged, this impairs clearance of cellular waste causing progressive loss of photoreceptor cells as they are no longer nourished by the RPE.
The effect of light equivalent to that emitted by mobile devices on retinal pigment epithelial cells was studied by Moon et al. (1) and demonstrated that reactive oxidative species were produced and reduced cellular function. That being said, a full understanding of human exposure to blue light may not be possible as it is not often the case that cells are directly exposed to blue light as in experimental conditions. Shang et al compared the effects of white and blue LED lights on retinal cells of rats, the results showing that the rats exposed to lights of lower blue light emission had considerably less damage. (2) This was done at a distance of 20 cm over a 12-hour period for up to 28 days. As demonstrated in this study, animal studies conducted generally use intensities and durations of light exposure that would rarely occur in real life therefore it is unclear if experimental animal data can be correlated to human light exposure. Due to the inability to imitate human exposure to blue light, at this stage, it is difficult to determine a direct link between AMD and blue light. Neelam K. et al evaluates several studies whereby patients with varying stages of macular degeneration and their light exposure is assessed. (3) A number of these studies do show potential links between higher exposure to visible light (including blue light) and the development of macular degeneration. These large studies are however also limited to the fact that AMD has a complex disease process and can also be affected by other factors such as genetics as well as diet.
BLUE LIGHT CAN BE BENEFICIAL
The best way to detect astigmatism is to book in for a comprehensive eye exam. A prescription check is carried out to determine the amount of astigmatic correction required.
Eye conditions like keratoconus are also diagnosed using a corneal topographer. This is an instrument that captures and displays an image of the cornea, creating a map that allows the practitioner to assess the curvature of the cornea and any irregularities.
ARE BLUE LIGHT FILTERS NECESSARY
The Royal Australian and New Zealand College of Ophthalmologists (RANZCO) have noted that “… there is little evidence with respect to using blue light blocking spectacles to improve visual performance. In addition, there are no studies showing such filters can conserve macular health.”
“Filtering out the blue light from screens is not necessary in general use”.
WHAT DO WE OFFER AT MICHAEL HOLMES PREMIUM EYEWEAR?
Blue light filters can be applied to lenses here at Michael Holmes Premium Eyewear. With the lack of strong evidence with regards to the efficacy of blue light filters and eye function, it is for this reason that we leave it up to the individual to decide whether they would like this additional filter. This is not a routine suggestion made by our Optometrists.
WHAT CAN YOU DO?
RANZCO has suggested that there may be a benefit to reducing screen time or using night mode settings on digital devices in the evening to reduce interruption to circadian rhythms.
General measures to reduce eye strain include regular breaks (the 20/20/20 rule involves 20 minutes of near work then taking a 20-second break to look 20 feet ahead of you) as well as ensuring that the appropriate spectacles are worn for certain tasks. It is recommended that you consult your optometrist if symptoms of eyestrain persist.
References
Moon J et al Blue light effect on retinal pigment epithelial cells by display devices. Integr Biol 2017 May 22;9(5):436-443.
Yu-Man Shang. White Light–Emitting Diodes (LEDs) at Domestic Lighting Levels and Retinal Injury in a Rat Model. Environmental Health Perspectives volume 122 | number 3 | March 2014
Neelam K. et al., The role of blue light in the pathogenesis of Age-related Macular Degeneration, Points de Vue, International Review of Ophthalmic Optics, N71, Autumn 2014