Extent of the Visual Field

Dynamic and tachistoscopic perimetric field tests on more than 400 normal individuals between 16 and 91 years of age showed a shrinkage of the visual field as a function of age. Up to age 60, sensitivity changes are only slight but then become appreciably greater. The sensitivity loss, especially in the parafoveal and peripheral retina, is similar to that produced by reducing the oxygen tension of respiratory gas mixtures. Reducing the oxygen tension in the breathing air of young individuals can lower their retinal sensitivity to the same level measured in individuals 30 to 50 years older. Changes in peripheral retinal sensitivity in the aged may be due to reduced retinal metabolism. Also, lattice degeneration and retinal breaks are more frequently seen in patients with chronic pulmonary diseases than in patients with normal lungs.