Fourier Analysis of Textural Variations in Human Normal and Cataractous Lens Nuclear Fiber Cell Cytoplasm

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

“…Age-related nuclear cataracts, the most common form of human cataracts (Murthy et al, 2007), begin as white hazy scattering in the nuclear core and progressively involve more of the nucleus as the cataract matures. Ultrastructural features that have been reported from our laboratory to be contributory to the scattering and opacity of human lens nuclei include enlarged extracellular spaces, extracellular space deposits (Costello et al, 1992;, distinct 1-4 µm globular particles called multilamellar bodies (Gilliland et al, 2001;Gilliland et al, 2004) and texturing of fiber cell cytoplasm seen in thin sections Taylor and Costello, 1999;Freel et al, 2002). …”

“…These images were collected with care, avoiding features that could confound calculations like membranes, compression bands, knife marks and other known variations due to sample preparation. Fourier analysis was carried out on each of these images using the fast Fourier transform algorithm of Digital Micrograph software, the basis and theory of which have been discussed in earlier publications (Taylor and Costello, 1999;Freel et al, 2002). Fourier analysis also helped detect obvious defocus or imperfections undetectable by the naked eye in these relatively low-contrast images during their collection and such images were not used in the analyses.…”

“…TEM staining intensity has been used as an indicator of protein density and refractive index by many researchers (Gisselberg et al, 1991;Vaezy and Clark, 1994;Taylor et al, 1997;Taylor and Costello, 1999;Clark, 2001). This is because heavy metal stains used in electron microscopy are generally non-specific (Glauert, 1965;Hayat, 1971) and refractive index is linearly proportional to density and relatively independent of the actual molecule (Michielsen, 1999).…”

“…The size of these presumably distinct particles, in theory, should be in the range 20-200 nm to produce significant scattering (Benedek, 1971;Bettelheim, 1985;Clark, 1994), a size range that can be visualized easily in thin-section electron micrographs. Yet, high-molecular-weight aggregate particles have not been observed within the cytoplasm of well-preserved human nuclear fiber cells (Costello et al, 1992;Taylor and Costello, 1999;Freel et al, 2002). Fourier analysis has been used to quantify cytoplasmic texturing in age-related nuclear cataracts (possibly from protein modification or redistribution) and to relate it to the scattering (Taylor et al, 1997;Taylor and Costello, 1999;Freel et al, 2002;Costello and Johnsen, 2004), as the technique is sensitive to small variations not perceived by eye.…”

“…Yet, high-molecular-weight aggregate particles have not been observed within the cytoplasm of well-preserved human nuclear fiber cells (Costello et al, 1992;Taylor and Costello, 1999;Freel et al, 2002). Fourier analysis has been used to quantify cytoplasmic texturing in age-related nuclear cataracts (possibly from protein modification or redistribution) and to relate it to the scattering (Taylor et al, 1997;Taylor and Costello, 1999;Freel et al, 2002;Costello and Johnsen, 2004), as the technique is sensitive to small variations not perceived by eye. Results from these studies show that the cytoplasm in mild age-related cataracts is similar to age-matched transparent lenses and in these instances cytoplasmic variations do not account entirely for the observed scattering.…”