Perimetric aspects of optic nerve aging.

Perimetry analyzes the efficiency of the entire visual system, but reveals the deterioration of even one of its components. Optic nerve changes, especially those of ischemic nature, which most frequently involve the middle and advanced age, cause typical perimetric findings. Manual kinetic perimetry is particularly indicated for the detection and definition of sectorial and global contractions. Manual static perimetry provides precise information on defect depth. Automated static perimetry quantifies the defect density in a large number of positions and also provides data on the significance of changes recorded during the follow-up. In normal subjects every type of perimetry shows a physiological decay of light sensitivity as a consequence of the aging of the visual system (about 2 dB per decade) and the reduced efficiency of the optic nerve is undoubtedly one of the components of this functional deterioration.