Why Is Blue Light Bad for the Eyes?

Reviewed on 4/9/2021

Blue light is part of the visible light spectrum with the shortest wavelength and highest energy.
Blue light is part of the visible light spectrum with the shortest wavelength and highest energy.

Blue light is part of the visible light spectrum with the shortest wavelength and highest energy. It can pass straight to the retina of the eyes through the passage to the cornea and lens. Sunlight is the main source of blue light and being outdoors gives a person maximum exposure to blue light. In addition, laptops, flat-screen television, tablets, and smartphones are manmade sources of blue light.

Blue light exposure from screens is small compared with the amount of exposure from the sun. However, the risk of blue light damage from screens is higher because of the close proximity to the screens and length of time spent on them.

What are the harmful effects of blue light on the eyes?

Direct penetration of crystals into the retina causes irreversible retinal damage. A wavelength between 300 and 400 nm can penetrate the cornea and be absorbed by the iris (the colored disc in the eyes) or pupil (the black center within the iris). High-energy short-wave blue light between 415 and 455 nm is the most harmful. Because people are gradually realizing the harmful effects of blue light, eye discomfort related to blue light is becoming a more prevalent concern.

Continued exposure to blue light could lead to

  • Myopia (nearsightedness): Because of blue light's short wavelength, the focus is not located in the center of the retina but rather in the front of the retina so that the long exposure time to blue light causes worsening of visual fatigue and nearsightedness. Symptoms such as diplopia and inability to concentrate can affect people's learning and working efficiency.
  • Cataract formation: The lens contains structural proteins that absorb short wave light, thus blocking potential blue light retinal damage. However, because it exerts its protective effect on the retina, the lens undergoes a decrease in transparency that leads to cataract formation.
  • Eyestrain: Blue light from computer screens and digital devices can lead to eyestrain. Fatigue, dry eyes, and bad lighting or how you sit in front of the computer can cause eyestrain. Symptoms of eyestrain include sore or irritated eyes and difficulty focusing.
  • Retina damage: Continued exposure to blue light over time could lead to damaged retinal cells. This can cause vision problems such as age-related macular degeneration.

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What are the benefits of blue light?

Blue light has several benefits as well:

  • It boosts alertness, helps memory and cognitive function, and elevates mood.
  • It regulates the circadian rhythm—the body’s natural wake and sleep cycle. Blue light can regulate the body clock through stimulating the secretion of melatonin in the pineal gland.
  • Paradoxically, decreased exposure to sunlight in children could affect the growth and development of their eyes and vision. However, no artificial light can compare to sunlight exposure. A deficiency in blue light exposure from the sun could contribute to the recent increase in myopia/nearsightedness.

How can eye damage due to blue light be prevented?

The prevention and control of blue light damage are becoming more and more important, and anti-blue light products are constantly emerging. Blue wavelengths that are beneficial during daylight hours are most disruptive at night.

Constant exposure to blue light from smartphones, tablets, and computer screens can be decreased by

  • Limiting the screen time.
  • Using screen filters.
  • Using yellow-tinted computer glasses.
  • Using gadgets in the night mode.
  • Keeping the brightness at 50% while using laptops.
  • Using anti-reflective lenses (although these are not 100% effective).

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References
https://www.aao.org/eye-health/tips-prevention/should-you-be-worried-about-blue-light

https://preventblindness.org/blue-light-and-your-eyes/

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