Common refractive errors include short sightedness (myopia), long sightedness (hyperopia) irregular curvature of the cornea (astigmatism) and age related lack of ability to refocus the lens of the eye (presbyopia).
Refractive errors are those that can usually be corrected with the use of glasses.
Childhood blindness is due to many conditions. Included in the are congenital conditions such as cataracts and congenital rubella, acquired infections and vitamin A deficiency. In addition to it's potential to cause blindness, vitamin A deficiency results in the death, annually, of an estimated 2 million children worldwide.
Trachoma is the the result of repeated infection by Chlamydia trachomitis usually occuring as a result of repeated transmission between children and their mothers.
It is the leading infectious cause of blindness world wide. Repeated infections cause scarring of the upper lid resulting in the eyelashes rubbing against the eye. This leads to abrasions eventually scarring and blindness. Infection is prevented by facial washing and good hygiene.
Current infection is treated with a single dose of a common antibiotic. Scarring of the lids is amenable to surgery to prevent the lashes from rubbing the eye. The SAFE strategy is the strategy of the International Trachoma Initiative and aimed at the elimination of trachoma worldwide by 2020.
Onchocerciasis, also known as river blindness, is caused by Onchocerca volvulus a parasitic infection transmitted by black flies. In the past control of the disease relied on trying to control the black fly populations in endemic areas. Now the disease may be effectively controlled by once annual treatment with an anti-parasitic drug.
The Vision 2020 World Health Organization inititive has prevented millions from going blind from onchocerciasis.