Adaptive optics wavefront correction using a damped transpose matrix of the influence function.

To assess the performance of adaptive optics and predict an optimal wavefront correction, we built a wavefront reconstructor with a damped transpose matrix of the influence function. Using an integral control strategy, we tested this reconstructor with four deformable mirrors in an experimental system, an adaptive optics scanning laser ophthalmoscope, and an adaptive optics near-confocal ophthalmoscope. Testing results proved that this reconstructor could ensure a stable and precise correction for wavefront aberration compared to a conventional optimal reconstructor formed by the inverse matrix of the influence function.

Spatial Assessment of Heterogeneous Tissue Natural Frequency Using Micro-Force Optical Coherence Elastography.

Analysis of corneal tissue natural frequency was recently proposed as a biomarker for corneal biomechanics and has been performed using high-resolution optical coherence tomography (OCT)-based elastography (OCE). However, it remains unknown whether natural frequency analysis can resolve local variations in tissue structure. We measured heterogeneous samples to evaluate the correspondence between natural frequency distributions and regional structural variations.

In vivo measurement of the lineal density of red blood cells in human retinal capillaries using high-speed adaptive optics ophthalmoscopy.

We present an automated method for measuring the lineal density of red blood cells (RBCs) in human retinal capillaries using adaptive optics near-confocal ophthalmoscopy (AONCO). The spatiotemporal traces of RBCs flowing in retinal capillaries were extracted from AONCO images, enhanced using the Gabor filter, the vesselness filter, and the Hough transform. A total of 43 capillary segments (each 50 µm long) were analyzed in 12 eyes of 12 subjects, and the measurement error of the automated method was 0.

Clinical Corneal Optical Coherence Elastography Measurement Precision: Effect of Heartbeat and Respiration.

Purpose: Normal physiological movements (e.g., respiration and heartbeat) induce eye motions during clinical measurements of human corneal biomechanical properties using optical coherence elastography (OCE).

An imaging system integrating optical coherence tomography and interferometry for in vivo measurement of the thickness and dynamics of the tear film.

Background: The outermost layer of the tear film consists of a thin lipid layer (LL). The lipid layer serves as a barrier against evaporation of the aqueous component of the tear film. The ability to simultaneously image both the lipid layer thickness and overall tear film thickness is novel, and will help further understandings of mechanisms of how the lipid layer assembles and interacts with the full tear film thickness.

Noninvasive characterization of erythrocyte motion in human retinal capillaries using high-speed adaptive optics near-confocal imaging.

The flow of erythrocytes in parafoveal capillaries was imaged in the living human eye with an adaptive optics near-confocal ophthalmoscope at a frame rate of 800 Hz with a low coherence near-infrared (NIR) light source. Spatiotemporal traces of the erythrocyte movement were extracted from consecutive images. Erythrocyte velocity was measured using custom software based on the Radon transform.

High speed adaptive optics ophthalmoscopy with an anamorphic point spread function.

Retinal imaging working with a line scan mechanism and a line camera has the potential to image the eye with a near-confocal performance at the high frame rate, but this regime has difficulty to collect sufficient imaging light while adequately digitize the optical resolution in adaptive optics imaging. To meet this challenge, we have developed an adaptive optics line scan ophthalmoscope with an anamorphic point spread function. The instrument uses a high-speed line camera to acquire the retinal image and act as a confocal gate.

High-speed adaptive optics line scan confocal retinal imaging for human eye.

Purpose: Continuous and rapid eye movement causes significant intraframe distortion in adaptive optics high resolution retinal imaging. To minimize this artifact, we developed a high speed adaptive optics line scan confocal retinal imaging system.

Methods: A high speed line camera was employed to acquire retinal image and custom adaptive optics was developed to compensate the wave aberration of the human eye's optics.

Adaptive optics parallel near-confocal scanning ophthalmoscopy.

We present an adaptive optics parallel near-confocal scanning ophthalmoscope (AOPCSO) using a digital micromirror device (DMD). The imaging light is modulated to be a line of point sources by the DMD, illuminating the retina simultaneously. By using a high-speed line camera to acquire the image and using adaptive optics to compensate the ocular wave aberration, the AOPCSO can image the living human eye with cellular level resolution at the frame rate of 100 Hz.

Association between MMP-12-82A/G polymorphism and cancer risk: a meta-analysis.

Background: Numerous studies have focused on the association between MMP-12-82A>G polymorphism and cancer risk, but produced inconsistent results. Therefore, we performed a meta-analysis of case-control study to evaluate the association of MMP-12-82A>G polymorphism and cancer risk.

Methods: A systematic literature search was conducted among PubMed, Web of Science, Science Direct, China National Knowledge Infrastructure (CNKI) and Wangfang databases updated on May 1st, 2015.