UV radiation: The damaging effects on your eyes

What is UV radiation?

Ultraviolet (UV) radiation is a form of electromagnetic radiation that originates from the sun and man-made sources.  Most of the different types of electromagnetic radiation emitted by the sun are visible (HEV) light, UV rays and infrared rays. While UV rays make up only a very small portion of the sun’s rays, they are the main cause of the sun’s damaging effects on the eyes. UV rays are an overload of energy that creates an imbalance in the chemical structure of the body’s molecules. This causes cell damage and abnormalities.  As UV rays travel with sunlight, the rays are able to pierce through the thin layer of skin of the eyelids when the eyes are closed or partially closed, making it possible for the rays to reach the eye despite being closed.

If direct sunlight therefore continuously reaches the eyes, it could lead to serious eye problems over time and put eyesight at risk.

Three types of UV radiation

  • UVA rays have the least energy among UV rays. UVA rays can pass through the cornea and overexposure can cause cataracts. They can affect your central vision if the macula (a part of the retina at the back of your eye) is damaged.
  • UVB rays have marginally more energy than UVA rays. With overexposure, UVB rays also cause sunburn and can damage the DNA in skin cells. They are believed to be responsible for most skin cancers.  Wrinkles and other signs of premature aging of the skin are also thought to be caused by UVB rays. Overexposure to the sun’s UVB radiation is associated with a number of eye problems, including pterygia, pingueculae, photokeratitis and cataracts.
  • UVC rays have more energy than the other types of UV rays. Fortunately, the atmosphere’s ozone layer blocks nearly all the sun’s UVC rays. UVC rays can however come from some man-made sources.

Eye problems from UV exposure

  1. Macular Degeneration

UV rays may lead to macular degeneration (AMD), a leading cause of vision loss for older people. AMD is one of the results of the sun’s high-energy visible (HEV) radiation, also known as blue light. Unlike UV radiation, HEV rays are visible and people with low levels of vitamin C and other antioxidants are more likely to suffer from retinal damage as well as AMD from HEV radiation.

  • Cataracts

A cataract is a clouding of the eye’s natural lens, the part of the eye that focuses the light we see. Apart from age-related cataracts that develop slowly, there are other causes for an earlier onset in younger people. One factor that may lead to cataracts and that can be controlled, is spending too much time in the sun without appropriate ultraviolet ray (UV) protection. UVB rays are responsible for causing cataracts.

  • Eye melanoma

This is a type of cancer that can develop inside the eye or on the conjunctiva.  It will develop in the cells that produce colour pigment.  Ocular or eye melanoma is rare, although it is the most common eye cancer in adults. Eye melanomas can be difficult to detect as they form in the part of the eye which isn’t visible when looking in a mirror.  It doesn’t present early signs or symptoms either – another good reason for regular eye examinations.

  • Pinguecula 

This is a yellowish, non-cancerous growth on the conjunctiva (or clear membrane over the white part of the eye) and is harmless. A pinguecula is a deposit of protein, fat, or calcium. It is usually found near the inside corner of the eye or near the nose.

  • Pterygium

Also known as surfer’s eye, a pterygium is believed to be caused by exposure to excessive amounts of UV light. It is more common in people living in sunny areas and who work outdoors. Other factors include wind, air pollution and further environmental irritants. A benign growth of tissue, it develops on the conjunctiva. The growth is often triangular in shape and if left untreated, it can extend across the pupil or cause the surface of the eye to change shape. It may also involve the cornea and eventually the growth may block vision. Pterygia are more common in males and in people older than 40 years of age.

  • Eyelid Cancers

Skin cancer around the eyelids is caused by prolonged UV exposure. The skin of the eyelid is very thin and therefore susceptible to sun damage. Basal cell carcinoma, the most common type of cancer found on eyelids, has a reddish nodule appearance. Fair skinned people and people with light coloured eyes are more at risk as they have less melanin or skin pigment. Most eyelid cancers only appear after the age of 50.

  • Corneal Sunburn

Corneal sunburn or photokeratitis is damage to the eye caused by ultraviolet (UV) rays. It can be very painful and cause vision loss for up to two days.  The inside of the eyelids, the cornea’s thin surface layer and the conjunctiva (the clear tissue covering the white part of the eye) are usually affected.

It is usually caused by exposure to UV rays when spending long hours in the sun, at the beach or snow skiing without proper eye protection. It could also occur from a man-made source such as tanning beds and welding torches. You should also never stare at the sun as this could burn the retina, causing long term damage.

Extended UV exposure results in more severe symptoms. These include pain, blurred vision, redness, tearing and light sensitivity among other.  

How to avoid UV damage to your eyes

The best solution to avoid UV damage is to protect your eyes effectively and continuously from the sun. Always choose sunglasses that have UV400 protection which can therefore block at least 99-100% of UV rays. Spectacle wearers can now also get sunglass level UVR protection in clear lenses with new Zeiss UV Protect. This blocks harmful UVR up to 400 nm in its clear plastic lens materials.

Sources: www.who.int; www.aoa.org; www.zeiss.co.za