Scattering angle resolved optical coherence tomography measures morphological changes in colonies.

Significance: An unmet need is recognized for early detection and diagnosis of neurological diseases. Many psychological markers emerge years after disease onset. Mitochondrial dysfunction and corresponding neurodegeneration occur before onset of large-scale cell and tissue pathology.

Approaches for Monitoring Warfighter Blast-related Exposures in Training to Develop Effective Safety Standards.

Introduction: Traumatic brain injuries are of concern to the sports and military communities because of the age of the participants and costly burden to society. To markedly reduce the impact of traumatic brain injury and its sequela (TBI-S), it is necessary to determine the initial vulnerability of individuals as well as identify new technologies that indicate early signs of TBI-S.

Materials And Methods: Currently, diverse methods have been used by the authors and others in laboratory settings to reveal early signs of persistent TBI-S including simulation modeling of the effect of rapid deceleration on the deviatoric strain (shear force) imposed on specific brain regions, auditory evoked potential (AEP) measurements to determine injury to the auditory cortex optokinetic nystagmus (OKN) measures sensitive to vestibular trauma, and optical coherence tomography (OCT) measures that reveal changes in central visual function obtained noninvasively by examination of the retina.

Scattering Angle Resolved Optical Coherence Tomography Detects Early Changes in 3xTg Alzheimer's Disease Mouse Model.

Purpose: Clinical intensity-based optical coherence tomographic retinal imaging is unable to resolve some of the earliest changes to Alzheimer's disease (AD) neurons. The aim of this pilot study was to demonstrate that scattering-angle-resolved optical coherence tomography (SAROCT), which is sensitive to changes in light scattering angle, is a candidate retinal imaging modality for early AD detection. SAR-OCT signal data may be sensitive to changes in intracellular constituent morphology that are not detectable with conventional OCT.

Scattering-Angle-Resolved Optical Coherence Tomography of a Hypoxic Mouse Retina Model.

Several studies have noted a correlation between retinal degeneration and traumatic encephalopathy (TE) making the retina a leading candidate for detection and assessment. Scattering-angle-resolved optical coherence tomography (SAR-OCT) is a candidate imaging modality to detect sub-resolution changes in retinal microstructure. SAR-OCT images of murine retinas that experience a hypoxic insult-euthanasia by isoflurane overdose-are presented.

Effect of image registration on longitudinal analysis of retinal nerve fiber layer thickness of non-human primates using Optical Coherence Tomography (OCT).

Background: In this paper we determined the benefits of image registration on estimating longitudinal retinal nerve fiber layer thickness (RNFLT) changes.

Methods: RNFLT maps around the optic nerve head (ONH) of healthy primate eyes were measured using Optical Coherence Tomography (OCT) weekly for 30 weeks. One automatic algorithm based on mutual information (MI) and the other semi-automatic algorithm based on log-polar transform cross-correlation using manually segmented blood vessels (LPCC_MSBV), were used to register retinal maps longitudinally.

Fourier optics analysis of phase-mask-based path-length-multiplexed optical coherence tomography.

Optical coherence tomography (OCT) is an imaging technique that constructs a depth-resolved image by measuring the optical path-length difference between broadband light backscattered from a sample and a reference surface. For many OCT sample arm optical configurations, sample illumination and backscattered light detection share a common path. When a phase mask is placed in the sample path, features in the detected signal are observed, which suggests that an analysis of a generic common path OCT imaging system is warranted.

Degradation in the degree of polarization in human retinal nerve fiber layer.

Using a fiber-based swept-source (SS) polarization-sensitive optical coherence tomography (PS-OCT) system, we investigate the degree of polarization (DOP) of light backscattered from the retinal nerve fiber layer (RNFL) in normal human subjects. Algorithms for processing data were developed to analyze the deviation in phase retardation and intensity of backscattered light in directions parallel and perpendicular to the nerve fiber axis (fast and slow axes of RNFL). Considering superior, inferior, and nasal quadrants, we observe the strongest degradation in the DOP with increasing RNFL depth in the temporal quadrant.

Retinal nerve fiber layer reflectance for early glaucoma diagnosis.

Purpose: Compare performance of normalized reflectance index (NRI) and retinal nerve fiber layer thickness (RNFLT) parameters determined from optical coherence tomography (OCT) images for glaucoma and glaucoma suspect diagnosis.

Methods: Seventy-five eyes from 71 human subjects were studied: 33 controls, 24 glaucomatous, and 18 glaucoma-suspects. RNFLT and NRI maps were measured using 2 custom-built OCT systems and the commercial instrument RTVue.

Micro-patterned drug delivery device for light-activated drug release.

Background: The primary goal of this study was the fabrication, long-term stability, and measured release of a marker dye from a micro-patterned drug delivery device using (i) mechanical puncture and (ii) photodisruption with an ophthalmic Nd:YAG laser.

Materials And Methods: A drug delivery device was made from a transparent bio-compatible polymer. The device consisted of two 2.

Changes in morphology and optical properties of sclera and choroidal layers due to hyperosmotic agent.

Light scattering in the normally white sclera prevents diagnostic imaging or delivery of a focused laser beam to a target in the underlying choroid layer. In this study, we examine optical clearing of the sclera and changes in blood flow resulting from the application of glycerol to the sclera of rabbits. Recovery dynamics are monitored after the application of saline.

Birefringence measurement of the retinal nerve fiber layer by swept source polarization sensitive optical coherence tomography.

A Swept Source Polarization-Sensitive Optical Coherence Tomography (SS-PS-OCT) instrument has been designed, constructed, and verified to provide high sensitivity depth-resolved birefringence and phase retardation measurements of the retinal nerve fiber layer. The swept-source laser had a center wavelength of 1059 nm, a full-width-half-max spectral bandwidth of 58 nm and an A-line scan rate of 34 KHz. Power incident on the cornea was 440 µW and measured axial resolution was 17 µm in air.

Variation of fluorescence in tissue with temperature.

Background And Objective: Previous studies demonstrated a decrease in fluorescence intensity as tissue temperature increased. In vitro samples were increased from room temperature and in vivo canine liver from body temperature. This study investigated variations in fluorescence intensity with temperatures starting at 14°C and compared in vivo and in vitro results for consistency.

Perfusion in hamster skin treated with glycerol.

Background And Objective: The objective of this article is to quantify the effect of hyper-osmotic agent (glycerol) on blood velocity in hamster skin blood vessels measured with a dynamic imaging technique, laser speckle contrast imaging (LSCI).

Study Design/materials And Methods: In this study a dorsal skin-flap window was implanted on the hamster skin. The hyper-osmotic drug, that is, glycerol was delivered to the skin through the open dermal end of the window model.

Detection of Gold Nanoshells in Tumors Using Diffuse Optical Spectroscopy.

This study demonstrates the use of diffuse optical spectroscopy (DOS) for the noninvasive measurement of gold nanoshell concentrations in tumors of live mice. We measured the diffuse optical spectra (500-800 nm) using an optical fiber probe placed in contact with the tissue surface. We performed studies on tissue phantoms illustrating an accurate measurement of gold-silica nanoshell concentration within 12.