A major structure/function relationship in the eye lens is that between the constituent proteins, the
crystallins and the optical property of refractive index. Structural breakdown that leads to cataract has
been investigated in a number of studies; the concomitant changes in the optics, namely increases in
light attenuation have also been well documented. Specific changes in the refractive index gradient that
cause such attenuation, however, are not well studied because previous methods of measuring refractive
index require transparent samples. The X-ray Talbot interferometric method using synchrotron radiation
allows for measurement of fine changes in refractive index through lenses with opacities. The findings of
this study on older human lenses show disruptions to the refractive index gradient and in the refractive
index contours. These disruptions are linked to location in the lens and occur in polar regions, along or
close to the equatorial plane or in lamellar-like formations. The disruptions that are seen in the polar
regions manifest branching formations that alter with progression through the lens with some similarity
to lens sutures. This study shows how the refractive index gradient, which is needed to maintain image
quality of the eye, may be disturbed and that this can occur in a number of distinct ways. These findings
offer insight into functional changes to a major optical parameter in older lenses. Further studies are
needed to elicit how these may be related to structural degenerations reported in the literature.