Recently, a device has been created to determine molecular interactions that occur in the nucleus of the lens, called Quasi Elastic Laser Scattering Device (QLS). 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 low energy lasers and offered for further development and testing at the NEI. We therefore propose to conduct a preliminary study to evaluate the usefulness and reproducibility of this instrument for quantitating lens changes.