We have all seen commercials on TV and social media about eye wear that blocks blue light. But what is blue light? Does it really damage our eyes? Most importantly, do we need blue light blockers?
Sunlight is made of red, orange, yellow, green, blue, indigo and violet light. They combine to form the white light we see, also called the visible spectrum. Sunlight is the largest source of blue light. Other sources includes:
CFL (compact fluorescent light) bulbs
Flat screen LED televisions
Computer monitors, smart phones, and tablet screens
Blue light is short wavelength and high in energy. Blue light exposure from digital screens such as cell phones are tablets is small compared to exposure from the sun. Blue light exposure suppress melatonin in the brain, helping to keep us awake. Thus exposure to blue light at night time can disrupt our circadian rhythm and sleep.
Blue light is not all bad. Blue light not only regulate sleep/wake cycle, it boosts alertness, helps memory and cognitive function and elevates mood. Not enough exposure to the sunlight can affect growth and development of eyes and vision and leads to the development of nearsightedness. Some studies suggest blue light exposure, especially at close range and long duration, from tablets and cell phones can lead to retinal damage but more research needs to be done in clinical setting.
Often time, long duration use of digital devices leads to a condition called digital eyestrain. Digital eyestrain refers to a combination of symptoms such as blurry vision, burning, stinging or tearing of the eyes associated with prolonged use of digital devices. Staring at a computer screen or digital device reduce blink rate thus leading to disruption and evaporation of the tear layers causing burning and stinging sensation. Prolonged digital device use at near can put strain on the muscles that help the eyes focus.
Dr. Dau recommends limiting digital device use 2-3 hours before bedtime to ensure a well rested night of sleep. She also recommends utilizing the 20/20/20 rule when working on computer. Every 20 minutes, look at something about 20 feet away for about 20 seconds. Using a good quality artificial tears may help with comfort. Dr. Dau also prescribes blue blocking anti-glare coating to all her patients, especially those with prolong use of digital devices to help reduce eyestrain.