When it comes to keeping your eyes healthy and protecting your vision, blue light from electronic devices is the least of your concerns. In fact, we are exposed to far more blue light from the sky than from our computer screens. If being outside on a sunny day does not damage your retina then neither would electronic devices, which are dim by comparison (O’Hagan et al., 2016). Although laboratory studies have shown that blue light can damage retinal cells, these are experiments done on retinal cell cultures in petri dishes or mice that have been exposed to high intensity blue light for long hours (Suter et al., 2000; Youn et al., 2009). In fact, human eyes are different from mice; humans have protective features such as the macular pigments and the blocking ability of the crystalline lens, which absorbs blue light before it reaches the retina (Figure 2). To date, there is no conclusive evidence that suggests that blue light from electronic devices can cause AMD in humans. Compared to aging, smoking, cardiovascular disease, high blood pressure, and being overweight, blue light is a minimal risk factor for the development of AMD. (Armstrong & Mousavi, 2015).  Hence, blue light blocking glasses have no added benefit in protecting against AMD. However, we can protect ourselves from AMD by eating a proper diet, especially foods high in omega-3 fatty acids. Moreover, the eye fatigue and irritation associated with prolonged screen time is unrelated to blue light, but because we do not blink enough when we stare at our screens, our eyes tend to dry out. Dry eyes lead to temporary blurry vision, eye fatigue and irritation (Loh & Redd, 2008). In addition, when you are too focused on the screen, the inner muscles of the eye tighten, resulting in eye strain (Blehm et al., 2005). To battle eye strain, the American Optometric Association recommends following the 20-20-20 rule; every 20 minutes take a 20 second break and look 20 feet away into the distance to allow the muscles to relax and refocus. Also, blinking often and using lubricating eye drops can help prevent your eyes from drying out. 

Although blue light from electronic devices is not harming your retina, it’s not exactly harmless. There is extensive evidence that shows that blue light can affect our biological clock, also known as the circadian rhythm. The circadian rhythm is a natural process that regulates the sleep-wake cycle by responding to light changes in the environment. Specifically, photosensitive retinal ganglion cells, or ipRGCs, play an important role in modulating this cycle(Srinivasan et al., 2009). They do so by sending light input signals to the suprachiasmatic nucleus (SCN) of the hypothalamus, a major circadian oscillator that regulates the production of melatonin – the darkness hormone (Srinivasan et al., 2009). Melatonin is released by the pineal gland in the brain in response to darkness to promote sleepiness and reset the circadian rhythm (Srinivasan et al., 2009). Studies have shown that blue light suppresses melatonin, making you less sleepy (Esaki et al., 2016; Srinivasan et al., 2009). In fact, all different types of light can suppress the melatonin hormone, which is why keeping your room dim before going to bed is highly recommended. However, an experimental study showed that melatonin was suppressed twice as long when people were exposed to blue light (460nm) compared to green light (555nm) (Wahl et al., 2019). Hence, blue light wavelengths have a more potent effect on human circadian rhythm than other short-wavelength visible light (Wahl et al., 2019).   

While exposure to blue light is important for keeping us alert and enhancing our cognitive performance during the day, chronic exposure to blue light around bedtime can compromise sleep quality. Recently, blue light blocking glasses have gained traction in selectively filtering out blue-wavelength light to potentially ameliorate shifts in circadian rhythm caused by blue light. A randomized control trial reported that wearing blue light blocking lenses 2 hours before bedtime for a week had significant improvements in sleep, compared to wearing clear lenses, in individuals with insomnia symptoms (Shechter et al., 2018). Thus, wearing blue light blocking glasses can help improve sleep quality, especially for individuals working night shifts or spending time on their computers before going to sleep. Alternatively, putting your devices away 2 or 3 hours before going to bed can help improve sleep quality and duration. 

Blue light blocking glasses may have some benefits in reducing melatonin suppression at night, however, there is no evidence that it can help protect against retinal damage. To maintain eye health it’s important to keep them lubricated and relaxed during long computer sessions. Following the 20-20-20 rule, blinking often, and using lubricating eye drops could significantly reduce eye strain and irritation. Moreover, dimming lights and screens before bedtime can help reduce the impact of blue light on your biological clock and improve sleep quality.