Change With Age of the Refractive Index Gradient of the Human Ocular Lens

Refractive index of the crystalline lens in young and aged eyes

“…The changes in refractive error and ocular dimensions for these groups have been reported previously 6,7 and are similar to those of previous studies by other workers. 1,2 While the axial length shows no significant change, an increase in the thickness of the crystalline lens was associated with a decrease in the anterior chamber depth.…”

“…16 When we modelled the crystalline lens as a gradient refractive index structure, we found the mean surface refractive index was 1.386 ± 0.007 for the young group and 1.394 ± 0.006 for the old group for an assumed refractive index at the centre of the lens of 1.406. The results from this study confirm the conclusions from the previous analysis of this data 6 and the conclusion that the decrease in power of the crystalline lens required to maintain a more or less constant refractive error in the ageing eye is due to a change in the gradient refractive index of the lens. The results of this study suggest that this change in refractive index gradient is due, in part, to a increase in the surface refractive index of the lens.…”

“…Hemenger, Garner and Ooi 6 confirmed this suggestion from biometric data 7 for 48 early adults and 48 late adults and found that there was a significant difference in the refractive index gradient for the two groups. In modelling these changes, Hemenger, Garner and Ooi 6 assumed the refractive index at the centre of the lens to be 1.406 and at the surface of the lens to be 1.386, that is, the values of the Gullstrand No 1 eye.…”

“…The basic data in this study were identical to those in previous reports. 6,7 Subjects were matched within and between groups for both sex and refractive error. The protocol of this study was approved by the University of Auckland Human Subjects Ethics Committee.…”

“…In modelling these changes, Hemenger, Garner and Ooi 6 assumed the refractive index at the centre of the lens to be 1.406 and at the surface of the lens to be 1.386, that is, the values of the Gullstrand No 1 eye. Note that while the findings of these two studies were similar, there was a major difference in methodology in that the surface refractive index used to model the changes by Pierscionek 4 was 1.34 and by Hemenger, Garner and Ooi 6 was 1.386.…”