In vivo "cataractograms" of transgenic mice using a compact backscatter dynamic light scattering (DLS) probe

Purpose. A compact fiber optic probe developed for fluid experiments in the challenging conditions of microgravity on the space shuttle orbiter has been applied to obtain "cataractograms", 3-D topographical maps, of the early onset of cataractogenesis in transgenic mice. Methods. The compact probe (about 1 cm) positioned in front of an eye, delivers a low power (50 jj\V) laser light into the eye and guides the light which is backscattered by different components of the eye through a receiving optical fiber to a avalanche photodiode (APD) detector and then to a digital correlator. Each DLS measurement is completed within 5-10 seconds. In this work cataractograms are generated using laser light to detect changes related to the earliest onset of cataractogenesis. The animals chosen for testing in vivo were anesthetized transgenic mice expressing the HIV-1 protease ranging in age from postnatal day 16 (eye opening) to day 24 (appearance of overt cataract) as well as normal mice of the same ages. Results. No cataracts were detected from day 16-21. The later cataractograms show a small opacity developing near the posterior pole on day 22 and dramatically spreading into nuclear and anterior segments of the lens on day 23. Conclusions. Good quality cataractograms can be obtained using a compact DLS probe. Preliminary results indicate that changes can be detected and quantitated in the lenses of the transgenic mice at the early stages of cataract development and this device appears to represent a significant improvement for early detection and quantitation of cataract formation.