The glaucomatous visual field.

The characteristic visual field defect in chronic simple glauconma occurs as a result of damage to individual bundles of nerve fibres in the optic nerve head. Chronic simple glaucoma, while the most frequent cause, is not the only cause of nerve fibre bundle defects. The causes ofsuch defects were divided by Harrington (i 965) into those occurring at the disc, those resulting from lesion of the anterior nerve, and those due to lesions of the posterior nerve and chiasm (Table).