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Ultraviolet (UV) light protection and eyes

Posted on 11 June 2014

UV protection for the eyes


What is UV radiation?

UV stands for ultraviolet light and refers to the electromagnetic radiation that emits from the sun. It provides humans with much needed Vitamin D and provides happiness and comfort for many. The downside is that too much exposure to UV radiation can cause sunburn, skin cancer and eye damage.

How does UV damage the eyes?

The body is designed with its own inbuilt eye protection against UV radiation. The design of the human face gives a certain amount of protection through the hooded eyebrow ridge and eyelashes covering the eyes. We also have an intrinsic reflex of squinting or closing the eyes when exposed to particularly harsh or bright light like when you look at the sun, your body automatically squints or an arm will lift to shield the eyes.

Unfortunately these naturally occurring protections are not always enough when dealing with excessive UV radiation.  UV radiation is stronger when reflected from certain surfaces including sand, water and snow. None of our natural defences can assist in these more extreme conditions. Furthermore, UV radiation still exists on cloudy days when reflexes such as squinting will not occur. The result is that eyes need more protection than our natural mechanisms offer.


What are the effects of UV on the eyes?

Excessive UV exposure increases the risk of various eye diseases including:

         Growths

         Cataracts

         Cancer

         Snow blindness

Growths on the eye often appear at a young age for surfers, skiers, farmers and anyone else who has excessive exposure to sun. UV radiation is heightened around more extreme conditions near rivers, oceans and mountainous areas. Any activity that regularly places a person in these conditions will increase their chances of eye damage.

Growth types vary but the most common is called a pterygium. This is literally a growth that grows on the surface of the eye, extending from the white part of the eye across to involve the cornea. They can be harmless but vision loss can occur if the growth extends and expands across the cornea to involve the pupillary area. In these cases, surgery is required for removal.


Cataracts may take a long time to develop but UV exposure increases the risk of developing cataracts later in life. Cataracts are one of the leading eye diseases in Australia. According to the Australian Institute of Health and Welfare, over 31% of people aged over 55 suffer from cataracts. This increases to over 70% in the age group over 80. If the cataracts are not affecting the vision too much, they may be treated with an adjusted prescription to eyeglasses and bifocals or multifocal contact lenses. If the vision is excessively obscured, the cataract may need to be surgically removed whereby the lens of the eye is replaced with an artificial one. 


Cancer of the eye can include a melanoma in the eyeball or basal cell carcinoma on the eyelid. While researchers continue to understand cancer, eye cancer may be related to long term UV exposure. Cancer is generally addressed by surgery.


Snow blindness is also known as photokeratitis, which is a temporary blindness caused by excessive UV light reflecting from the snow. It is usually experienced by skiers or people moving around in extremely high altitudes in the snow. Recovery usually takes no more than 48 hours but the victim will experience discomfort and the eyes may even swell shut. The reason is that the cornea has inflamed from too much UV exposure and limited protection. Sunglasses do not always provide enough UV protection because they allow light to enter through the sides. 


How do contact lenses protect against UV radiation?

Contact technology has advanced to include UV protection that is built into the lens. The interesting fact is that contact lenses can now offer the most comprehensive protection from UV radiation to the eye even more so than sunglasses or eyeglasses with UV protection. The reason is that the contact lens is able to protect from UV rays coming in the periphery, or through the sides of the glasses. The following diagram depicts the areas that glasses are not able to protect and how the contact lens provides fuller coverage.



 

Contact lenses provide a range of UV protection and are labelled as Class 1 and Class 2 to differentiate.


Class

UV protection

Class 1

90 - 96% UVA

 

99 -100% UVB

Class 2

70% UVA

 

95% UVB

 

UVA rays are long-wave rays. UVB rays are short-wave rays. Research continues to develop regarding which radiation causes what damage to the eyes and skin but both have the capacity to cause harm when overexposed.


When buying contact lenses it pays to check that they have a UV protection component. The Acuvue Oasys brand of contact lenses offers both Class 1 and Class 2 UV protection across their entire range.


Contact your contact lens practitioner to discuss which type of lens best suits your eyes to ensure adequate protection from the harmful effects of the sun.


It is important to remember that it is still essential to wear sunglasses to protect your eyes and surrounding tissue from UV light.