Here are some facts about the effects of ultraviolet light and blue light on our eyes. These facts are based on research studies, scientific journals and our experience as an eye care provider.

Visible light (the light which is visible to us like violet, indigo, blue, green, yellow, orange and red) covers the wavelength of 380 nm to 780 nm. Beyond the visible light which has shorter or greater wavelength, isn’t visible. Ultraviolet (UV) light spectrum is from 100 nm to 380 nm. It is invisible to human eye and wavelengths on the lower end can be very harmful.

Harmful Light:

UV-Violet 100 nm to 380 nm: Very harmful to eyes. UV exposure can cause or speed up the development of cataracts.
Blue-Violet 400 nm to 460 nm: Induced HEV light can cause retina damage, cell death, and lead to age related macular degeneration*. 460 nm +/- 10 nm (glare caused by LCD displays, mobile displays, LED lights etc.): can cause melatonin suppression, increased alertness and increased heart-rate, which can lead to sleep disorders and heart conditions*. In ophthalmology, high-energy visible light (HEV light) is high-frequency, high-energy light in the violet/blue band from 400 to 500 nm in the visible spectrum. HEV light has been implicated as a cause of age-related macular degeneration*.

Beneficial Light:

Blue-Turquoise 470 nm to 500 nm: Good blue light, which can be useful for various treatments such as sleep disorders and seasonal depression. Can influence and help regulate Circadian sleep/wake cycle and memory.


Blue light (range of 465 nm to 495 nm) is good and essential for our health. This is the range of blue-turquoise light which is essential for the regulation of pupil size of our eyes. Blue light in general can have healthy affects on vision as well as the body. Inadequate light exposure means inadequate blue-turquoise light, which can throw off our Circadian biological clock and our sleep/wake cycle. According to Review of Optometry, blue-turquoise light really plays a vital role in the general health of the individual.

Ultraviolet light has three zones:

UV light has a degenerative effect on our eyes particularly the conjunctiva, cornea and the lens. In conjunctiva, it can cause a degenerative change such as a Pterygium and Pinguicula. Prolonged exposure of UV light to the cornea can lead to exposure keratitis (keratitis Inflammation of the cornea, caused by an infection or inflammatory process. Symptoms include eye pain or discomfort, light sensitivity, foreign body sensation, grittiness and tearing.), in which permanent degenerative change occurs to the cornea. The lens of our eyes will absorb maximum UV light to protect our retina so UV light absorption by lens contributes to the formation of cataracts.

This image outlines the increasing and decreasing damage of the spectrum of light to your eyes:


1- Degenerative changes of retina: In a research study by Essilor and Paris Vision Institute in 2008, they found a specific band of blue light (415 nm to 455 nm) is most harmful to the retina by splitting the visible light into multiple bands of 10 nm and each band was then focused on a porcine retinal pigment epithelial (RPE) cells for several hours. The blue-violet light that was discovered as part of this study is a 40 nm band of visible light that causes the maximum retinal cell death. Reference:
Smick K et al. Blue light hazard: New knowledge, new approaches to maintaining ocular health. Report of a roundtable sponsored by Essilor of America. March 16, 2013, NYC, NY.

The use of digital devices and modern lighting such as CFL (compact fluorescent) bulbs and LED lights is very common. These devices emit significant amount of blue light. CFL emit 25% of harmful blue light. LED emit 35% of harmful blue light.

Interestingly, the cooler the white LED, the higher the blue light emittance. It is estimated by 2020, 90% of all of our light sources are to be LED lighting. Exposure to blue light is everywhere and only increasing.

As shown in the picture, UV light affects the front of the eye where blue light affects the retina. Protecting yourself from both UV and blue light is important.

2- Sleep Cycle Disruption : While light of any kind can suppress the secretion of melatonin, blue light has a stronger affect. Blue light exposure at night disrupts the quality of sleep. Our bodies have an internal “clock” also known as a biological clock, which is situated in the brain. This clock regulates our circadian rhythm, a 24-hour biological cycle that influences many internal functions, which determines our sleep. When it gets dark in the evening, a part of the brain called the pineal gland secretes the hormone melatonin, which signals to our bodies and brains that it is time to go to sleep. Blue light, whether from the sun or a laptop, is very effective at inhibiting melatonin production and disrupt the biological clock*.

Lack of sleep is one of the most important causes of computer vision syndrome according to Jeffrey Anshel, OD, president of the Ocular Nutrition Society and a frequent lecturer on computer vision syndrome. Researchers believe that we are more prone to the risk of heart attack, obesity, diabetes and various cancers due to lack of sleep or disruption of circadian rhythm. Lack of sleep has also been linked with mood problems, anxiety and depression, and increased risk of accidents.

3- Blue light contributes to digital eye strain:

“No one knows for sure at this point if prolonged use of digital devices actually causes permanent damage to the eyes, but it’s well established that it causes eye strain and discomfort.” Explained Gary Heiting, OD, senior editor of

Blue light has short wavelengths, which causes light to scatter more easily than other visible light. When looking at a computer screen or other digital devices that emit significant amounts of blue light, the scattering of light reduces contrast which leads to digital eye strain*. If you’ve ever experienced dry or irritable eyes, blurred vision, eye fatigue, or head, neck and back pain after using a computer or Smartphone, then consult your eye care provider.


According to Review of Optometry, blue light has shown to cause significant over accommodation*. These accommodative changes are constant even in decreased luminance. This mechanism is also thought to trigger night myopia and is a potential driver of the myopic shift seen in our population in recent years.


  1. Avoid looking at bright screens beginning two to three hours before bed.
  2. If you work a night shift or use a lot of electronic devices at night, consider wearing blue-blocking glasses.
  3. Expose yourself to lots of bright light during the day, which will boost your ability to sleep at night, as well as your mood and alertness during daylight.
  4. Maintain a comfortable working distance from computer to avoid hunching closer to the screen.
  5. Follow 007 rule: Character height should be 0.007 times viewing distance to be legible. For example: For 20 inch viewing distance, 007 rules says that minimum character height is 0.14 inch (0.007 x 20” = 0.14”). Therefore, 12 point type at 20” viewing distance satisfies the 007 rule.
  6. Follow the 20-20-20 rule: After every 20 minutes of computer viewing, one should look into the distance 20 feet away for 20 seconds to allow the eyes to refocus. The American Optometric Association suggests a break of 15 minutes after 2 hours of continuous computer use.
  7. Routine comprehensive eye health exams: Digital eye strain can occur even in a minor change of refractive power of your eyes. Check your eyes every year and wear appropriate glasses that protect your eyes from harmful blue light.
  8. Ask your eye care provider about glasses that block blue light. There are a number of brands of eyeglass lenses and coatings that can reduce your exposure to HEV and bad blue light when using digital devices. See below for the solutions and technology we offer:

Kodak Total Blue Lens
CHOICE BluSelect lens with Premium Anti-reflective coating
– Blue Blocker Anti-Reflective coating (available on any lens)
Essilor Crizal Prevencia coating
BluTech Lenses

*HEALTH CANADA NOTICE: Correlation of high energy blue light and the following diseases and disorders: retinal damage/degeneration/retinal degenerative disease, macular degeneration/age related macular degeneration (AMD), increased risk of certain types of cancers, heart disease, obesity and diabetes, glaucoma, permanent damage to eyesight, cataracts, sleep disorders, eye strain, and loss/reduction of vision has not been completely scientifically proven. Since many factors can cause these conditions, consumer caution is advised. We would like to properly advise and provide our patients with the most recent optical technology advancements by offering visual solutions to improve your overall visual well being. With visual comfort and high energy blue light protection in mind, the information we provide is to help you make the best choice for your eyes.