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What is Ultraviolet Light: How Does It Effect My Vision?

December 07, 2017

What is Ultraviolet Light: How Does It Effect My Vision?

Ultraviolet light or UV light is a form of electromagnetic radiation that is invisible to the eye. It is invisible to us because its wavelengths are shorter than those of visible light.

UV light make up less than 10% of the sun’s total light output and only a fraction of this 10% actually penetrates the earth’s surface. However small your exposure to UV light, it still affect the cells which make up your body, through the chemical process of ionization. This process causes electrons and atoms to react with each other in ways they generally would not, for example:

  • In plants, UV ray over exposure, may impair photosynthesis and reduce the size of the plant. Plants in fact have pigments which protect them from UV light.
  • For animals there are a few species that can physically see this light spectrum, animals such as birds, reptiles and fish. Even some mammals can see UV light, rats, bats and reindeer.
  • In humans, UV light exposure causes suntans and freckling (yeay), but over exposure causes damage such as skin cancer as well as eye care related issues like cataracts (Cataracts are the leading cause of blindness in the world), pterygiums, corneal sunburns and macular degeneration (boooo).

 

There are 3 types of UV rays:

  • UV-A - Penetrate the deeper skin layers where the connective tissue and blood vessels are affected. The lens of the eye absorbs most of the UVA rays to protect the retina, however continuous absorption results in connective tissue breakdown and degenerative changes within the lens, thus eventually affecting the retina as well.

  • UV-B - Cause more damage to the functionality of the eye because they reflect of any surfaces especially roads, water and snow, this increases the likelihood of cell damage. The cornea protects the eye against UVB but the conjunctiva (the mucous membrane that covers the front of the eye and lines the inside of the eyelids) stays exposed.

  • UV-C - These are the most threatening form of UV light as they contain the highest energy levels but luckily they are completely absorbed by the ozone layer and do not present any threat to our vision or skin at this stage.

 

    Now that we have gone through the dangers of UV light, let’s look at ways of protecting yourself from it:

      1. Be mindful of the amount of exposure you have to UV light. Avoid tanning beds or UV producing equipment.

        2. When you do spend time outdoors be sure to use protective items like:

            • Wear a wide brim hat or large peak caps which can reduce your UV exposure up to 50%;

              • We all know this one, wear sunscreen;

                • Invest in UV protective eyewear. When choosing your eyewear there are a few things to consider: 

                    • Frame: Large or wraparound frames are not only more fashionable but they also  protect the eyes and the sensitive skin around the eyes from UV light and their reflections.

                    • Lens Coatings: a UV filter is essential, you should always check the label of your purchase to make sure they provide 100% protection against UVA and B rays. You can also order UV coatings for clear spectacles from Vision Works Optometrists. 

                    • Lens Tint: Brown / tan lenses provide the best protection against blue / purple UV light because these darker colours neutralise the lighter UV rays. One added benefit is that they don’t distort other colours.

                  3. Prevention is always better than cure, so we recommend visiting an eye doctor regularly to check for UV related visual issues.

                  Check out our infographic on protecting your vision this silly season.

                   

                  Love Your Eyes:

                    Vision Works Optometrist’s perform comprehensive eye tests to check for signs of UV-induced visual conditions. Most conditions can be treated, or prevented from becoming serious with early detection.

                    Sources:

                    http://www.thevisioncompany.co.za/resource_centre/articles/uv-radiation.html

                    By Tash Casey