Objective: To use dynamic light scattering to clinically assess early precataractous lens protein changes. Methods: We performed a cross-sectional study in 380 eyes of 235 patients aged 7 to 86 years with Age-Related Eye Disease Study clinical nuclear lens opacity grades 0 to 3.8. A dynamic light-scattering device was used to assess α-crystallin, a molecular chaperone protein shown to bind other damaged lens proteins, preventing their aggregation. The outcome measure was the α-crystallin index, a measure of unbound α-crystallin in each lens. The association of the α-crystallin index with increasing nuclear opacity and aging was determined. Results: Therewasa significant decrease in the α-crystallin index associated with increasing nuclear lens opacity grades (P<.001). There were significant losses of α-crystallin even in clinically clear lenses associated with aging (P<.001). The standard error of measurement was 3%. Conclusions: Dynamic light scattering clinically detects α-crystallin protein loss even in clinically clear lenses. α-Crystallin index measurements may be useful in identifying patients at high risk for cataracts and as an outcome variable in clinical lens studies. Clinical Relevance: The α-crystallin index may be a useful measure of the protective α-crystallin molecular chaperone reserve present in a lens, analogous to creatinine clearance in estimating renal function reserve.
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