Observational Clinical Studies of Human Lens Transparency Using the Vision Index Pen.

Purpose: Preventing or delaying the onset of presbyopia and cataract formation remains a challenge. The goal of this study was to establish the utility of the Vision Index Pen (VIP), designed to measure in vivo dynamic light scattering (DLS) from the crystalline lens, in the detection of early cataract or loss of accommodation and to show reproducibility through trials at two independent sites. The gradual loss of transparency of the lens was characterized by the lens crystallin aggregation index (LCX) derived from measured DLS data.

Homodyne fiber optic backscatter dynamic light scattering.

Optical homodyne detection in the backscatter direction is achieved through a pair of collinearly located fibers in a cylindrical probe body. One fiber illuminates the scattering solution while the other fiber provides optical mixing of the backscattered optical field with a local oscillator derived from the Fresnel reflections at the glass interfaces of the sample container. Homodyne detection is possible over a broad range of particle size and sample concentration with a single probe design.

A dual detector capillary waveguide biosensor for detection and quantification of hybridized target.

We describe a novel technique for improving the sensitivity of analytical instruments based on the measurement of fluorescent intensity. Independent measurement of the Rayleigh scattered intensity component by means of a second photodetector leads to normalized data, which are independent of various experimental parameters. Incorporation of this technique into a fully automated capillary waveguide biosensor improved the instrument sensitivity by a factor of three.

In vivo dynamic light scattering characterization of a human lens: cataract index.

Purpose: To characterize the cataractous state of the living lens by a single parameter, derived from in vivo dynamic light scattering measurements.

Methods: Dynamic light scattering, in conjunction, with a fiber optic transmitter/receiver, was used for measuring the intensity autocorrelation of the light scattered in the backward direction from the living human lens. The fiber optic transreceiver provided a rapid means for active positioning and collection of the back scattered light from any point inside the lens.

Multi-capillary optical waveguides for DNA sequencing.

Cylindrical capillaries can be used as optical elements in a waveguide, where refraction will confine an appropriately focused light beam to pass through the interiors of successive capillaries in a flat parallel array. Such a capillary waveguide allows efficient illumination of samples in multiple capillaries with relatively little laser power. Analytical expressions derived under paraxial and thin-lens approximations provide guidance in selecting the capillary sizes and the refractive indices that will produce the waveguiding effect, but accurate predictions require exact ray tracing.