Blue light has been a growing topic over recent years. With increased time spent indoors and eLearning, many patients have questions about how it can affect their eyes, should they be concerned, and what can be done to help. Let us start by defining blue light and how it relates to UV light.
Wavelength is important when defining blue light because it helps to explain how it can affect your vision. Blue light is part of the visible light spectrum and has a wavelength between 400-500nm.
This is different from UV light, which is part of the invisible spectrum between 100-400nm. Blue light causes eye strain because the shorter and smaller waves make it scatter more than other colors. The increase in eye strain can lead to more headaches while using digital devices. Additionally, blue light is used to control your circadian rhythm, which controls your sleep pattern, and subsequently regulates your metabolic system. This is critical because your metabolic system is what determines your cortisol levels. Cortisol levels control a person’s weight, stress, and immune response. Lastly, unlike UV light, blue light is able to reach the back of the eye.
In today’s world it is virtually impossible to go a day, let alone a few hours, without looking at a digital device. LED screens have become an enormous part of our day to day lives between work, school, and free time. Obviously, we cannot eliminate screen time for ourselves or our children, but it is important to establish a healthy balance. Natural outdoor sunlight is crucial for emmetropization, the process of developing perfect vision. Work and play spaces should be set up in the home near natural light to assist in this. It is recommended that children have very little to no screen time until the age of 5. Even after 5, breaks in screen time should occur every 30 minutes.
The blue light from digital devices will trick your body into thinking the sun is still out, resulting in melatonin not being produced to adequate levels. Since melatonin is used to control your sleep cycle, this adversely affects your quality of sleep. Along with eye strain, this is a reason why digital devices should be discontinued an hour before bed. If this is not possible, night modes on screens can help to reduce eye strain.
As mentioned previously, the shorter wavelengths of blue light cause the waves to scatter at a much higher rate when compared to other light. The use of paper reading material is on the decline due to our society’s reliance on technology. When the human eye focuses on paper, the light source is constant so pupils only need to react once. However, when a digital device is used, the pupils are constantly reacting because they are trying to focus on the pixels of the screen. Since the muscles that control your pupils are constantly working to accommodate, they experience more strain and fatigue like any other over worked muscle would.
Blue light is able to travel through the eye and reach the macula, which is the part of the retina responsible for your most central and detailed vision. The concern is that, with increased digital device usage, blue light may lead to damage such as macular degeneration. Some animal studies have indicated damage to retinal cells from indoor blue light. However, it is important to note that no human data has been collected and more research needs to be completed in order to determine the true long-term effects on the human eye.
What can be done to help protect your eyes? There are many devices and lenses being made to help reduce your exposure to blue light. When exploring your options, it is a good idea to know what you are looking for. It is impossible to block out large percentages of light without affecting vision.
Therefore, it is important focus our efforts on specific wavelengths to maximize protection. Digital devices with backlit LED screens tend to emit blue light peaking at 450nm with virtually none between 400-410nm. Most therapeutic benefits, such as preventing against potential macular damage and headaches, are achieved by blocking wavelengths at 460nm. Good products should block around 430470nm to achieve the highest level of efficacy.
There are several other ways to reduce strain on your eyes in addition to protecting your eyes from excessive blue light. First, do not hold reading material or digital devices too close to your face. The closer something is to you, the harder your eyes have to work to stay focused. Next, try practicing the 20/20/20 rule – for every 20 minutes of near work (computer screen distance or closer), take 20 seconds, and look 20 feet or more away (out of a window or down a hallway). You do not need to be exact, but 20/20/20 is an easy way to remember to give your eyes a break. Lastly, as stated before, try to stop working an hour before bed to give your eyes a break from blue light.