By Nigel Little 

Night contact lenses  worn only while sleeping are a new way to correct short-sightedness - once removed in the morning, the wearer enjoys clear natural vision all day long. At the same time, this means no more need to purchase expensive prescription sunglasses which otherwise often restricts people from choosing fashionable designs or changing their sunglasses more often when new ranges of designer sunglasses are released. In some cases, the costs involved mean that people do not bother wearing sunglasses at all and this lack of protection is likely to cause increasing cases of eye conditions such as cataracts, warm weather conjunctivitis and pterygium (known as ‘Surfer's Eye') due to increased exposure of the eyes to direct sunlight with its potentially harmful ultra-violet radiation (UVR).

Ozone layer depletion associated with global warming decreases the atmosphere's natural protection from the sun's harmful UVR. According to the World Health Organisation, approximately 18 million people are blind from cataracts of whom at least 1 million suffered from high UVR exposure. This is now the basis for a large study covering 5,000 people being undertaken by the All India Institute of Medical Sciences which aims to quantify the effect of environmental factors, UVR, suspended particles, environmental pollutants and aerosols on the prevalence and/or exacerbation of these eye diseases. The study expects to confirm that people take inadequate care in protecting their eyes from exposure to sunlight - often because of cost factors - which is where the introduction of night contact lenses  can at least enable short-sighted people to opt for lower cost protective eyewear.

UVR levels are influenced by a number of factors - the higher the sun in the sky, the higher the UV radiation level; the closer a person is to the equator, the higher the UV radiation levels. UV radiation levels are highest under cloudless skies but even with cloud cover, they can be high and UV levels increase by about 5% with every 1,000 metre altitude. Ozone absorbs some of the UVR from the sun but as the ozone layer is depleted, more UVR reaches the earth's surface. So regular wearing of sunglasses is strongly advised - even in countries like the UK where lower temperatures and regular cloud cover make people less conscious of the UVR risk. The availability of night contact lenses  means that being short-sighted no longer requires expensive prescription sunglasses to get protection - and you can stay fashionable too at lower cost.

Check if you are suitable for overnight ortho-k corrective contact lenses .