Over the last decade, a trend of adding blue light blocking filters to corrective glasses has emerged, aimed especially to people who spend a lot of their time looking at electronic devices. Opticians often justify this expensive option as being able to reduce the symptoms of digital eye strain, better one’s circadian rhythm, and decrease the potentially harmful effects of blue light on the retina. So then, are blue light blocking filters really worth the premium over the normal lenses?
In the modern world, many people spend a lot of their time looking at various sorts of electronic displays. These displays emit quite a lot of blue light in their emission spectrum, which is why they could contribute to the potential damaging effects it has. Or could they?
Blue light carries the most energy of the whole visible light spectrum
Blue light is electromagnetic radiation in the blue end of the visible spectrum. It has shorter wavelengths (380 – 500 nm) and carries more energy than red and green. The radiation with shorter wavelengths still is invisible to our eyes and is called ultraviolet (UV) radiation. It has an important role in human physiology as it regulates circadian rhythm and sleep cycle by the regulation of production of the hormone melatonin. Wavelengths around 470 nm inhibit the production of melatonin, which makes us more alert and less sleepy – useful during the day. Conversely, when the Sun goes down, the amount of blue light emitted by the Sun decreases and more melatonin is being produced, making us less alert and more sleepy – useful in the evening.
It can also be harmful to our eyes, especially to the photoreceptors of the retina, and has been associated with the development of age-related macular degeneration. That said, those associations are weak, and as the magnitude of blue light emitted by electronic devices is many times smaller than that emitted by the Sun, it is highly unlikely that computer screens would contribute to harmful effects of blue light to the retina.
Blocking filters may be useful in certain instances
We would like to conclude with the following. If you can afford the blocking filters, have them fitted, but if you do not it does not look like you are missing out too much. They certainly can block a small amount of potentially harmful blue light emitted by the Sun and perhaps even help ever so slightly with the circadian rhythm, especially for those who cannot refrain from using the computer of tablet 1-2 hours before going to sleep. Whether blue light filters also improve the symptoms of digital eye strain, which will be discussed in one of our future blogs, remains debatable. Currently, there is little evidence to support that.