Blue light-blocking lenses have taken off in recent years, but you might wonder if you need a pair and what they do for your eyes. And how damaging is blue light, anyway? We’ll explore the answers in this article.
What Is Blue Light?
The electromagnetic (EM) spectrum encompasses all electromagnetic radiation, including visible light that we can see. Types of radiation include radio waves, microwaves, infrared, ultraviolet, X-rays, and gamma rays. Visible light falls between infrared and ultraviolet on the EM spectrum, from about 380 to 700 nanometers.
Visible light consists of the colors of the rainbow, with blue light falling closest to ultraviolet light at approximately 380 nanometers. In other words, blue light has a shorter wavelength and higher energy compared with other colors on the visible light spectrum.
Blue Light Exposure and Eye Health
Blue light is present everywhere–in fluorescent lights, light-emitting diodes (LEDs), computer screens, smartphones, and tablet screens. However, the largest source of blue light comes from sunlight (nearly 100,000 times more than LEDs). Though blue light exposure from digital devices is far less than the sun, doctors are concerned that long-term use and viewing screens at a close distance can affect the eyes.
High-energy blue light passes through the cornea (front of the eye), penetrates the lens inside the eye, and reaches the retina (back of the eye). This means blue light can damage structures in the eye that are responsible for maintaining clear vision. Link to blue light reaching the retina illustration. Some of the primary eye diseases associated with blue light are age-related macular degeneration and cataracts.
Age-related macular degeneration is a disease that affects the macula, which is the central area of the retina responsible for fine detail, color, and central vision. Although studies have found that blue light damages retinal cells, the amount of blue light exposure used in these studies far exceeds what you are exposed to regularly.
At birth, the natural lens inside our eyes is clear. Over time, the lens absorbs blue light when we are exposed to the sun and other sources of blue light. This exposure can lead to the earlier development of cataracts (when the natural lens becomes yellow and more opaque). Both cataracts and age-related macular degeneration contribute to visual changes.
Blue Light and Digital Devices
Digital eye strain (DES) is a term used to describe a group of symptoms you may experience when viewing digital devices for prolonged periods. These symptoms include:
- Eye fatigue
- Dryness
- Burning eyes
- Red eyes
- Blurry vision
- Double vision
- Eye irritation
DES symptoms are often attributed to blue light exposure from screens, but there is conflicting evidence on whether this is true. Some studies found that blue light blocking lenses do not improve DES symptoms, while others suggest that these lenses may provide some relief. There are, however, other factors that contribute to DES:
- Uncorrected refractive error
- Preexisting dry eye disease
- Poor posture
- Improper lighting
- Improper viewing distance or angle
- Screen glare
Things you can do to improve DES include setting up an ergonomic workspace, using the correct eyeglass prescription, treating any existing dry eye, and taking frequent breaks on the computer. Here are some tips on optimizing your workspace:
- Set your computer screen about 18 to 24 inches away
- Position the screen to view at a 10 to 20 degrees downward angle
- The top of the screen should be no higher than eye level
- Activate the blue light filter setting if your device has one
- Use screen covers that reduce glare
- Reduce glare from overhead lighting and windows
- Take breaks every 20 minutes by looking away from the screen for 20 seconds (ideally at something in the distance)
Although more research is needed on DES and blue light, there are other benefits to blue light blocking lenses.
Blue Light and Sleep
Blue light isn’t all bad–it helps regulate your circadian rhythm (your body’s sleep-wake cycle). Proper regulation of the circadian rhythm helps with your:
- Sleep quality
- Mood
- Alertness
- Cognitive function
- Memory
- Metabolism
Blue light suppresses the release of melatonin, a hormone that helps your body know when it’s time to sleep. In addition, decreased melatonin levels are linked to chronic diseases such as cancers, cardiovascular disease, reproductive issues, gastrointestinal problems, diabetes, obesity, depression, and other disorders.
While exposure to blue light during the day is beneficial, increased blue light exposure before sleep affects your overall health. For this reason, looking at digital devices before bedtime isn’t ideal. Experts recommend discontinuing the use of smartphones, computer screens, and tablets 2 to 3 hours before sleep. If you must use your digital device, some studies suggest that blue blocking lenses improve sleep quality.
Are Blue Light Blocking Lenses Necessary?
We know the effects of blue light on health, but we also need to consider ultraviolet rays:
- Ultraviolet A (UVA) is linked to cataracts and macular degeneration. They also penetrate the skin deeply and cause skin cancers such as basal cell and squamous cell carcinomas (including on the eyelids).
- Ultraviolet B (UVB) is mainly absorbed by the ozone layer, but it can still cause sunburns of the skin and eyes (called photokeratitis). UVB also contributes to pinguecula and pterygium growths on the front of the eye.
Our primary source of UV exposure is the sun. When it comes to protecting our eyes from UV and blue light, sunglasses are most important. Sunglasses can block up to 100% of ultraviolet rays and at least 67% of blue light. Look for a pair that’s labeled UV400 or 100% UV protection. As for blue light blocking glasses, more research is necessary to determine whether they benefit our eye health. However, there seems to be some benefit in using them during the hours before bed to improve sleep quality.
One of the best ways to care for your eye health is to see your optometrist for yearly exams. They look for signs of cataracts, macular degeneration, sun damage, skin and eye cancers, and other eye conditions affected by blue light and UV exposure. Your optometrist also prescribes lenses to optimize your vision, digital device viewing, and sun protection. So get started by scheduling your eye exam today!