What should you know about Sunlight?

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Exposure to sunlight has its benefits. It helps regulate our sleeping patterns and reduce childrens’ risk of developing nearsightedness. Sunlight also aids in Vitamin D production and supports physiological processes. But exposure to harmful types of sunlight can cause lasting damage to the human body – including the eyes. 

Not all of the Sun’s Rays are the Same

The earth’s sun emits different types of radiation – from visible light to radio waves. Arranged upon the electromagnetic spectrum, the most significant types of sun radiation are categorized as visible and invisible light.

Invisible Light

Like the name implies, invisible light cannot be seen by the naked eye. Ultra-violet (UV) light is the invisible high-energy radiation portion of the electromagnetic spectrum.

  • UV-C (200-280 nm) – The highest energy level and is the most dangerous. Exposure to this type of light can cause mutations in plants and animals. The ozone layer of the stratosphere absorbs UV-C, so it does not reach the earth’s surface. However, UVC could become a greater concern if the holes in the earth’s ozone layer at the North and South Poles get larger.
  • UV-B (280-315 nm) – The mid-energy UV level is the most damaging to the body and has the greatest impact to the eyes. Exposure to UVB plays a key role in the development of skin cancer and is the main cause of sunburn and skin blistering. Also, it is closely lined with photokeratisis, cataracts, pterygium, and eye cancers.
  • UV-A (315-380 nm) – The majority of humans are exposed to large amounts of UVA throughout our lifetime. Accounting for 95% of the UV radiation emitted by the sun, UVA penetrates the skin more deeply than UVB and is a contributor to the aging and wrinkling of skin (also called photoaging). It also poses a significant threat to eyes and causes cataracts and Age Related Macular Degeneration.

 

While invisible light goes unseen by the naked eye, it emits the highest and most damaging radiation levels.

 

Visible Light

The portion of the electromagnetic spectrum visible to the human eyes is visible light. While much of this half of the spectrum is harmless and necessary in order for human beings to see, High Energy Visible Light (often called HEV or “Blue Light”) poses a significant risk to eye health. 

HEV Light

While HEV light has less energy than UV radiation, prolonged exposure to high-energy visible light may cause damage to the retina. Like UV light, exposure to blue light may also contribute to the premature aging of skin and Age Related Macular Degeneration (AMD). However, unlike UV radiation, exposing eyes to some blue light has a beneficial effect and is helpful in maintaining circadian rhythms, brain wave activity, hormone production, cell regeneration and other physiological processes.

 

Busting the Blue Light Myth

Blue Light has become an increasingly popular topic in last decade as digital devices and LED lighting become more common. But while it’s true the sources of blue light include things like laptop screens, smartphones and fluorescent lighting, the largest source of blue light of occurs outdoors and from the sun. In fact, a person has to spend 13 hours on a computer to expose the eye to the same amount blue light eyes are exposed to during 15 minutes in the sun.

Learn more about the hazards of blue light and download our CE Course

Take steps to protect eyes from light across the spectrum

Overall, the best way to protect eyes for a lifetime of healthy sight is to prescribe sunglasses that block 100% UV rays and the appropriate amount of HEV rays and clear, everyday lens solutions that block the most damaging light rays – indoors as well as outdoors.

 

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