CATARACT accounts for approximately 16 million cases of blindness worldwide. In most countries of Africa and Asia, it accounts for approximately half of all blindness.

A cataract results from a change of transparency of the normal crystalline lens in the eye. When the lens becomes opaque, it impedes the light from entering the eye. This condition causes gradual loss of vision and blindness. Cataract may have different origins: some children can be born with it and some cataracts develop after eye injuries. However, cataracts are largely related to the ageing process.

The older a person, the more chance there is of developing a cataract. The majority of people with cataracts are over 50 years of age. This means that, as life expectancy increases, more people will develop cataract and the number of blind will increase. By 2020, there will be some 1.2 billion people aged 60 years and over in the world with three-quarters living in developing countries. At present, the causes of ageing-related cataracts are not well known and prevention is therefore not generally possible. However, it seems that protection against excessive UV-irradiation may help prevent at least one form of cataract.

Usually, ageing-related cataract can be treated with a relatively simple operation to remove the opaque lens. Increasingly, even in developing countries, cataract surgery includes the use of intraocular lens implantation, which, however, requires sophisticated technology and adequately trained personnel. In the USA alone there are some 1.35 million cataract operations performed each year at a cost of US$ 3.4 billion.

While efforts are being made to increase access to intra ocular lens implantation through low-cost technology and training of personnel, simple cataract extraction with provision of spectacles is still practiced in the rural areas of many developing countries, where almost 90% of cataract-related blindness occurs.