Recently, a device has been created to determine molecular interactions that occur in the nucleus of the lens, called Dynamic Light Scattering Device (DLS). Preliminary studies have shown its potential in the detection of the earliest changes occurring in cataract, at the stage where anticataract treatment would theoretically be most effective in reversing, delaying or preventing cataracts. A new miniaturized version of this device has been developed by NASA using lower energy lasers and offered for further development and testing at the NEI. We recently conducted a pilot study to evaluate the usefulness and reproducibility of this instrument for quantitating lens changes, and found good reproducibility. We also determined that the most useful parameter to use is mean particle size derived from particle size distribution. We therefore propose to conduct a study on changes on the lens due to aging (age related changes), as well as on the three representative types of cataracts (nuclear, cortical and PSC).