There are many causes of blindness. In children, vision impairment may be due to birth defects, often a result of prematurity. Optic nerve damage, injury of the eye(s), and trauma to the part of the brain that controls vision may also result in blindness.
Magnitude. Corneal Opacity accounts for 3.46% of global blindness and 1.65% of global blindness and visual impairment (IAPB Vision Atlas). As a leading cause of blindness in children (Solomon, 2005) and within developing nations, Corneal blindness affects all age groups.
By percentage, DR caused 2.6% of all cases of blindness and 1.9% of all visual impairment in 2010, up from 2.1% and 1.3%, respectively, in 1990. The percentage of blindness caused by DR in 2010 ranged from less than 2% in Southeast Asia and Oceania to 5.5% or greater in southern Latin America.
Refractive errors are eye disorders caused by irregularity in the shape of the eye. This makes it difficult for the eyes to focus images clearly, and vision can become blurred and impaired. Refractive errors include eye problems such as myopia (short-sightedness), hyperopia (long-sightedness) and astigmatism (caused by an irregularly curved cornea).
Trachoma, an eye infection affecting both eyes, is the world’s leading cause of preventable blindness. According to the World Health Organization (WHO), trachoma is responsible for the visual impairment of 2.2 million people, of whom 1.2 million are irreversibly blind.