Corneal blindness: a global perspective

Diseases affecting the cornea are a major cause of blindness worldwide, sec ond only to cataract in overall importance. The epidemiology of corneal bli ndness is complicated and encompasses a wide variety of infectious and infl ammatory eye diseases that cause corneal scarring, which ultimately leads t o functional blindness. In addition, the prevalence of corneal disease vari es from country to country and even from one population to another. While c ataract is responsible for nearly 20 million of the 45 million blind people in the world, the next major cause is trachoma which blinds 4.9 million in dividuals, mainly as a result of corneal scarring and vascularization. Ocul ar trauma and corneal ulceration are significant causes of corneal blindnes s that are often underreported but may be responsible for 1.5-2.0 million n ew cases of monocular blindness every year. Causes of childhood blindness ( about 1.5 million worldwide with 5 million visually disabled) include xerop hthalmia (350000 cases annually), ophthalmia neonatorum, and less frequentl y seen ocular diseases such as herpes simplex virus infections and vernal k eratoconjunctivitis. Even though the control of onchocerciasis and leprosy are public health suc cess stories, these diseases are still significant causes of blindness - af fecting a quarter of a million individuals each. Traditional eye medicines have also been implicated as a major risk factor in the current epidemic of corneal ulceration in developing countries. Because of the difficulty of t reating corneal blindness once it has occurred, public health prevention pr ogrammes are the most cost-effective means of decreasing the global burden of corneal blindness.