The leading causes of blindness are cataract, glaucoma, age-related macular degeneration, corneal opacities, diabetic retinopathy, trachoma, and eye conditions in children such as that caused by vitamin A deficiency.

Age-related and diabetes-induced blindness is increasing throughout the world. However, blindness caused by infection is decreasing as a result of the initiatives of public health. Three-quarters of all blindness can be prevented or treated.

Anatomy of the Eye
The cornea, at the front of the eye, is the transparent film through which light first passes before traveling through the opening called the pupil. The cornea, which has a curved shape, acts like a camera to focus images on the retina, at the back of the eye.

The pupil monitors the amount of light that enters the eye. If the amount of light available is very little, the pupil widens and if it is too much, it constricts.

The iris, which appears as the coloured part of the eye, is responsible for regulating the size of the pupil.

The retina, at the back of the eye, is a multilayered structure which receives visual stimuli.

The optic nerve transmits information from the retina to the brain.