Ultraviolet (UV) radiation is one component of solar radiation. It is progressively filtered as sunlight passes through the atmosphere, in particular by the ozone layer. As the ozone layer is depleted, the protective filter activity of the atmosphere is reduced and more harmful UVA and UVB rays reach the Earth's surface. Sustained ozone depletion and enhanced levels of UV radiation will aggravate UV effects on the human skin, eyes and immune system.

The Global Solar UV Index (UVI) is a simple measure of the UV radiation level at the Earth's surface. It has been designed to indicate the potential for adverse health effects and to encourage people to protect themselves. The values of the index range from 0 upward and the higher the index value, the greater the potential for damage to the skin and eye, and the less time it takes for harm to occur.

New Zealand and Australia have the highest UVA and UVB levels in the world, and for that reason it's always been really important that we protect our skin and eyes from the sun. UV exposure of the eye depends on many factors: ground reflection, the degree of brightness in the sky leading to activation of the squint reflex, the amount of atmospheric reflection and the use of eyewear.

The acute effects of UV on the eye include the development of photokeratitis and photoconjunctivitis, which are like sunburn of the delicate skin-like tissue on the surface of the eyeball (cornea) and eyelids. While painful, they are reversible, easily prevented by protective eyewear.

Chronic effects include the possible development of pterygium (a white or cream colored opaque growth attached to the cornea), squamous cell cancer of the conjunctiva , cataracts and age related macular degeneration. Some 20 million people are blind around the world as a result of cataract. Of these, World Health Organization estimates that as many as 20% may be due to UV exposure.

The basic sun protective measures:

• Limit exposure during midday hours.
• Seek shade.
• Wear protective clothing. Wear a wide brimmed hat to protect the eyes, face and neck.
• Protect the eyes with wrap-around-design sunglasses or sun glasses with side panels. Up to 35% of UV light can come around the edges of ordinary spectacle frames.
• Use and reapply broad spectrum sunscreen of sun protection factor (SPF) 15+ liberally.
• Protect babies and young children as they are particularly sensitive to UV radiation.

Staying out of sun, either indoors or in shaded areas, during the four hour period around solar noon when UV radiation levels are highest is an effective mean of protection . It should be combined with using clothing, hats and sunglasses.

There is no need to buy very expensive sunglasses, $20 glasses are as good as any other as long as they are 100% UV light protective. Ideally, the lenses should cut out 100 percent of UV light, 85% of glare and 75% of infrared light or heat.