More than 250,000 Canadians have chronic open-angle glaucoma, the most common form of the disease. Glaucoma occurs due to damage to the optic nerve. While it is not known exactly how this occurs, there is an association between damage to the optic nerve and pressure within the eye due to build up of excess fluid within the eye. Over time the disease develops into a loss of peripheral (side) vision.
A cataract is a cloudy area over the lens of the eye. Cataracts can affect one or both eyes. Childhood cataracts are rare: they occur in one to three in 10,000 children.