Glaucoma is a series of diseases which damage the optic nerve. Damage to the optic nerve and retina causes blind spots in the field of vision. If the entire nerve is destroyed, blindness will occur. When light enters the eye, an image is focused onto the retina, the delicate nerve layer lining the inside back wall of the eye. The retina then transforms the light images into electrical impulses which are carried to the brain by the optic nerve.