Presbyopia - a maverick of human aging.

The aim of this study was to examine the extent to which the age-related variations of properties of the human lens may be able to account for presbyopia. Dimensionless linear regressions were calculated for age-related biological functions with special reference to ocular and lenticular ones. Their intercepts on the x-(age-)axis are compared, and their distribution is analyzed. An analysis was made of the effect of the growth of the lens on the relation between its shape and the proximal zonular anchorages on the one hand and the age-related variation of the angle between the zonule and the equatorial plane of the lens. The lens is not unusual in seeming to have evolved in support of a life-span of about 120 years. Presbyopia, however, fails to fit into the general picture and this is hypothesized to result from lenticular growth and a combination of factors which are not all governed by senescence. The potential involvement of the root of the iris throws an interesting light on the apparently worldwide variation of the condition.