Global Patterns of Eye Disease

According to the World Health Organization (WHO), there are about 135 million people who are visually impaired and 45 million people who are blind throughout the world. WHO reports that of the estimated 1.4 million children worldwide who are blind, 320,000 of them live in sub-Saharan Africa. Not only is the economic burden of global blindness high, but eye diseases such as cataracts, trachoma, glaucoma and onchocerciasis can result in death. In many cases, eye disease, blindness and the resulting fatalities could be prevented.

• Human Eye

Cataract

• Cataract is the No. 1 cause of blindness in the world. According to WHO, in 1998, more than 20 million people throughout the world were going blind because of cataracts. This is mainly because people living in poor economic conditions are unable to gain access to cataract surgery that would restore their sight. The biggest challenge is to be able to reduce the cost of the surgery as well as creating ways to provide it to people living in remote and impoverished areas. Cataract is also a significant problem in wealthier countries due to the cost of operations. Preventing the disease requires significant study into the risk factors.

Trachoma

• According to the National Council of Ophthalmology, trachoma is the second most prevalent cause of avoidable blindness and visual disorder. Trachoma (both active and blinding), occurs among impoverished populations. One of its main causes is recurrent and persistent infection with Chlamydia trachomatis, yet what is puzzling is that trachoma has completely vanished in certain areas of the world such as the Appalachian region of the U.S., India, Pakistan and Finland. Methods of preventing the disease include improving hygiene. Corrective surgery can correct trachiasis and also reduce scarring of the eyelids. Improvements in environmental sanitation can reduce the risk of recurrence.

Onchocerciasis

• The prevalence of onchocerciasis (also known as river blindness), and its progression to blindness has been dramatically reduced due to global programs, according to the National Council of Ophthalmology, yet it is still mostly concentrated in Africa. This is the third most common cause of preventable blindness. Environmental interventions such as cleaning polluted water sources and widespread treatment may mean that by 2010, this eye disease should no longer be a major public health issue, but it will still take up to 40 more years before the distribution of the drug treatment Mectizan can be discontinued.

Xerophthalmia

• Xerophthalmia, also known as dry eye syndrome, is a condition in which the eyes are no longer able to produce tears. It is caused by a very severe deficiency of vitamin A. This is a common cause of visual disability in South Asia and Africa, particularly among children. In young women, it can also cause night blindness. Many countries have helped reduce the prevalence of xerophthalmia by promoting and distributing vitamin A. The major obstacles to this have been in developing cost-effective methods to supplement diets with vitamin A.

Glaucoma

• Optic nerve damage caused by glaucoma is the fifth highest cause of global visual impairment and blindness. According to the International Council of Ophthalmology, primary angle closure glaucoma is a major cause of blindness, though interventions are looking promising. This type of glaucoma occurs primarily in people of Asian ethnicity. Strategies for prevention include the implementation of cost-effective screening techniques and studies to evaluate preventive measures.