ANTERIOR ZONULAR SHIFTS WITH AGE

The anterior and equatorial zonular insertions of 17 normal suspended lenses were studied with respect to age (17 to 90 years) by scanning electron microscopy. From our observations, with the normal lens growth, the distance between the lens zonular insertion and the equator (insertion-equatorial distance) increases; the distance between the insertion ring and the ciliary body (insertion-cb distance) remains relatively constant; and the circumlental space (equator-cb distance) decreases. These changes are most pronounced in the fifth decade and continue with age. Between ages 17 and 46, there are numerous equatorial zonules, while the older eyes are devoid of zonules in this region. However, in these older eyes fine zonules with the same morphology are seen anterior to the equator. Since the zonules are laid down early in development and their position on the capsule is fixed, these observations show a capsular shift resulting in a movement of zonules onto the anterior lens face. These findings show definitive changes with age in the architecture of the lens suspensory system which must be considered a factor in the failure of the lens to accommodate with advancing age (presbyopia). © 1979.