Pilot Study: Dynamic Light Scattering Device for Studying Early Changes in Cataract

Overview

This study will use a new dynamic light scattering device (DLS), developed jointly by NASA and the NEI, to study pre-senile cataracts (cataracts that develop in patients 55 years old or less). Cataract is a clouding of the lens that interferes with the passage of light to the retinal, impairing visual acuity. DLS uses a low intensity laser light (similar to that used in supermarket checkouts) to measures lens cloudiness. It detects changes in the human lens at the earliest molecular stages of cataract development, when anti-cataract treatment would be most effective in reversing, delaying or preventing cataract formation. Patients 55 years of age or younger with cataract may be eligible for this study. Candidates will be screened with the following tests and procedures: * Medical history and physical examination. * Eye examination, including measurement of visual acuity (vision chart) and eye pressure; examination of pupils and eye movements; dilation of the pupils for examination of the lens and the back of the eye (retina). * Cataract photography using a camera with a bright flash to assess the status of the cataract and evaluate future changes. * Blood drawing if necessary for clinical care. Participants will have a standard eye examination, as described above, plus DLS testing. For this procedure, the patient sits in front of the DLS device, with the chin placed on a chin rest. He or she fixes on a yellow-green target in the center of the camera lens. When the eye is properly aligned, the measurement is taken and the reddish light on the side of the camera lens turns on for 5 seconds. Measurements are taken on three layers of the lens. The procedure takes less than 30 minutes. Participants will be followed at the NIH clinic once a month for up to 1 year to follow progression of the cataract. The visits will include a repeat of some of the exams listed above.

Recently, a device has been created to determine molecular interactions that occur in the human lens in vivo and non-invasively, 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 anti-cataract treatment would theoretically be most effective in reversing, delaying or preventing cataracts. A new DLS device has been developed by NASA physicist Dr. Rafat Ansari using lower energy lasers, miniaturized and contained within a fiber optic tip, and further developed and tested under an NEI-NASA Inter Agency Agreement. 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 a useful parameter is mean particle size. We therefore propose to use the new NEI-NASA DLS device to detect and study, non-invasively and in vivo, the earliest molecular cataractous changes that develop rapidly in the lenses of patients less than 55 years of age, otherwise called pre-senile cataracts.