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M.B. Datiles, III, R.R. Ansari, K.I. Suh, G.F. Reed, S. Vitale, J.F. King, F.L. Ferris, III; Relation of Dynamic Light Scattering (DLS) Cataract Detection Device Parameters to Clinical Nuclear Lens Grades . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4134.
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To assess the association of Dynamic Light Scattering (DLS) parameters with clinical cataract grading and to determine the reproducibility of DLS measurements.
We conducted an NEI IRB–approved cross–sectional clinical study on normal and cataract patients using the NASA–NEI DLS clinical device. Dynamic or Quasielastic Light Scattering is a noninvasive, in vivo, safe, objective method to detect molecular changes in lens proteins. It has previously been used in animal studies to detect early lens changes leading to cataracts. All subjects gave informed consent and underwent complete eye examinations including AREDS lens nuclear clinical (NUC) grading. 2–5 DLS measurements of the lens nucleus were taken to assess reproducibility. The DLS probe is mounted on a keratometer base and uses a 3–D aiming system in concert with A–scan measurements to assure that light scattering measurements are consistently taken as close to the center of the lens nucleus as possible. For each DLS measurement, a particle size distribution within the small non–invasively sampled volume of the nucleus was estimated using the exponential sampling method (Stock and Ray 1985). From the typical bimodal distribution of particle sizes, summary parameters were calculated, including median log particle diameter (MLD) and fraction of intensity contributed by the high–molecular–weight particles (Fraction Large Diameter (FLD)). The relation of DLS parameters to NUC grades was assessed using mixture models (SAS version 9.1). Reproducibility was determined by the coefficient of reproducibility (standard error of measurement divided by the mean).
212 patients (343 eyes) were included. Mean age was 57 years (range, 18–86 years). NUC grades ranged from 0.0 through 3.8 (mean 0.75, SD 0.74). DLS parameters MLD and FLD increased significantly with increasing NUC grade (0.11 units/1–step change in grade, p < 0.0001, r2 = 0.51; 0.38 units/1–step change in grade, p<0.0001, r2 = 0.67, respectively). Coefficient of reproducibility was 0.028 for MLD (2.8%) and 0.0313 (3.13%) for FLD.
DLS parameters were significantly associated with AREDS clinical lens grading and gave reproducible results. These findings support further investigation of this non–invasive, objective approach for measuring early lens changes.
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