The light that reaches the human eye is comprised of non-visible and visible light, those being the wavelengths from 380 to 780 nm. Ultraviolet rays are considered non-visible. We’ve known for years that UV can cause damage to biological tissue such as our skin and eyes, which is why we apply sunscreen on our skin and should always protect our eyes with UV screens on our sunglasses. Blue light, however, is considered visible and because it penetrates all the way to the retina at a specific range it has the potential to cause damage to our eyes.
Blue light in the harmful spectrum may disrupt cellular metabolism in the retinal pigment epithelium layer. This layer contains melanin granules that attract and absorb the blue light wavelength and may then cause lesions that can lead to retinal cell death. This may then increase the risk of macular degeneration, particularly for those already at risk for it. Children under the age of 18 and patients who have had cataract implants are particularly at risk for retinal damage since their newer, clear lenses are less likely to filter out blue light than an older yellowed with age lens. However, and ironically, despite the fact that natural aging and yellowing of the lens in your eye may provide some protection for the retina against blue light, further exposure to bue light will accelerate cataract progression.
Blue light is not all bad. We enjoy a beautiful blue sky on a sunny day and we do need some of the natural blue light as a biological reminder to our bodies that it is daytime. This provides us with feelings of being alert, happy, energized and of being awake. In the absence of blue light, special cells in the retina are switched on and begin to produce melatonin, which lets our bodies know it is time to rest or sleep. Melatonin production at a particular time on a regular basis sets our sleep cycle and circadian rhythm to that time. Hence blue light signals our body when it is daytime and when it is nighttime. When we are exposed to artificial blue light such as that from our digital devices (computers, tablets, tv’s, cell phones etc) at night, our body is tricked into thinking it is daytime and suppresses the production of melatonin, our sleep inducing hormone. Continued disruption of melatonin production and consequent sleep patterns may also put one’s health at risk. A blue light filter in your lenses may therefore help you to have a better sleep if you are on your digital devices before bedtime.
In addition to disruption in sleep patterns, blue light can cause eyestrain. Blue light radiates at a short wavelength which scatters easily, consequently interfering with visual contrast and increasing eye fatigue.
In summation, a blue light filter in our lenses can help to eliminate many adverse effects that blue light producing digital devices have. Other helpful advice would be to decrease screen brightness, hold the digital device further from our eyes, take frequent breaks or limit use of our digital devices and try to avoid our digital devices within one hour before bedtime.