UV radiation and its harmful effects

Wide-brimmed hats and sunglasses will provide protection against the sun's rays.
Wide-brimmed hats and sunglasses will provide protection against the sun's rays.ST FILE PHOTO

Overexposure to ultraviolet (UV) light can damage the skin and lead to freckling, sunburn and an increased risk of certain forms of skin cancer, said Dr Eugene Tay, medical director and ophthalmologist at Singapore Vision Centre.

UV light is present in sunlight and can also be produced by lighting equipment such as sun lamps.

Of the three types of UV radiation, short-wavelength UVC is the most damaging, but it is filtered by the earth's ozone layer and does not reach the earth's surface, according to the World Health Organisation (WHO). Medium-wavelength UVB accelerates skin ageing and significantly promotes the development of skin cancer.

UVB is the cause of sunburn and snow blindness (photokeratitis), and is absorbed by the cornea, said Dr Tay.

It is also linked to the development of pterygia - benign growths that can cause discomfort and blurry vision.

Long-wavelength UVA, which accounts for approximately 95 per cent of the UV radiation reaching the earth's surface, can penetrate the deeper layers of the skin and is responsible for a tanning effect, said WHO.

It is the most harmful type of UV radiation, said Dr Tay, as it is transmitted to the crystalline lens and retina of the human eye, which may increase the risk of cataracts and macular degeneration.

He offers some tips on how to protect your eyes.

•Wear sunglasses that can block 100 per cent of UV radiation, especially when you have to spend long periods in the sun.

•Choose sunglasses with large lenses or those that wrap around the face, as these give better protection.

•Wear a hat with at least a three-inch brim all around. This helps to shield your eyes and eyelids - where the skin is extremely thin - from the sun.

•Seek shade whenever you are outdoors, especially between 10am and 4pm.

Joyce Teo

A version of this article appeared in the print edition of The Straits Times on November 17, 2015, with the headline 'UV radiation and its harmful effects'. Print Edition | Subscribe