Light scattering of normal human lens I. Application of random density and orientation fluctuation theory

Abstract

Light-scattering intensities in the I parallel and I+ mode were obtained on thin sections of three human lenses. Random density and orientation fluctuation theory, without cross correlation, was employed to evaluate light-scattering parameters. Both the density correlation distances, as well as the orientation correlation distances, were related to structural elements in the lens fiber cell that have been observed by other investigators with different techniques. The magnitude of these fluctuations were evaluated, and it was demonstrated that the density fluctuations are the main contributors to light scattering in normal human lenses. Changes in the light-scattering parameters were evaluated as a function of position within the lens. The changes observed agree with the biochemical data in the literature that reflects that an aging process occurs when one proceeds from the periphery of the lens toward the center.

Analysis of nuclear fiber cell cytoplasmic texture in advanced cataractous lenses from Indian subjects using Debye–Bueche theory

“…The correlation functions were interpreted in terms of high-molecular-weight protein aggregates dispersed in a medium of lower average refractive index. The most important findings were that the density fluctuations predominated (much larger than orientation fluctuations) and that the average size of the aggregates for aged lenses was about 300-450 nm with an average separation of about 400 to 1200 nm (Bettelheim and Paunovic, 1979). This approach was also applied to human cataractous lenses Siew et al, 1981).…”

“…Previously, Debye-Bueche analysis, referred to as the 'random fluctuation theory,' was performed on the scattering from transparent human lenses (Bettelheim and Paunovic, 1979). They included an extension of the theory for the evaluation of orientation fluctuations that might detect anisotropic structures, such as bundles of cytoskeletal elements (Bettelheim and Paunovic, 1979).…”

“…They included an extension of the theory for the evaluation of orientation fluctuations that might detect anisotropic structures, such as bundles of cytoskeletal elements (Bettelheim and Paunovic, 1979). The calculated correlation functions were determined from scattering curves of frozen-thawed sections of lenses cut at different depths perpendicular to the optic axis.…”

“…The most consistent finding was that the density fluctuations were more prominent than orientation fluctuations and that considerable variability among cataracts suggested that each cataract had distinguishing characteristics. It is worth noting that the orientation fluctuations showed rapid changes at the cortex/nucleus interface, where cell compaction is evident, and in the central nucleus where the anisotropy probably involves the membranes, because no cytoskeletal elements are present (Bettelheim and Paunovic, 1979;Bettelheim et al, 1981). In the current study we have emphasized only the density fluctuations and have imaged cytoplasm only in regions without membranes, thus avoiding anisotropic features that could contribute to the orientation fluctuations.…”

“…In the current study, we have estimated the contribution of the packing and organization of the fiber cell cytoplasm to light scattering from the in vivo lens nucleus in transparent lenses to lenses with a range of opacities. The well-established Debye-Bueche theory for inhomogeneous materials (Debye and Bueche, 1949) has been used in this analysis, as has been used in the past for characterizing scattering from the lens (Bettelheim and Paunovic, 1979;Bettelheim et al, 1981;Bettelheim and Siew, 1983), because this theory is robust and directly applicable to thin sections of densely packed amorphous proteins. The analysis indicates that the organization of the cytoplasm is altered markedly in advanced age-related nuclear cataracts and is a major contributor to the total light scattering by cataractous nuclei.…”