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Raman spectroscopy (RS) and Optical Coherence Tomography (OCT) are powerful tools for optical analysis of tissues with complimentary strengths. OCT excels and visualizing tissue microstructure while RS can relay tissue biochemical composition. Both instruments have significant potential to serve as valuable tools in non-invasive characterization of the rodent models of retinal disease. In this abstract we present the design and application of a common detector combined RS-OCT instrument for evaluating the morphological and biochemical differences in a rat model for oxygen induced retinopathy. Rat pups that have undergone a variable oxygen treatment are compared to rats raised in room air. Images and spectra collected at an age of 26 days postnatal demonstrate differences in both the thickness of the inner and outer nuclear layers, but also in the biochemical composition.

We present in vivo noninvasive retinal and choroidal perfusion maps with phase-variance optical coherence tomography (pvOCT). We acquired a pvOCT volumetric data set of a normal subject and visualized blood circulation in the retina and the choroid. En face projection views of the retina as well as the choroid were generated from a manually segmented volumetric data set. In addition, the processed pvOCT images were compared to current standard imaging modalities used for retinal and choroidal vasculature visualization in clinical settings, including fluorescein angiography (FA) and indocyanine green angiography (ICGA). © 2013 Copyright SPIE.

We demonstrate the feasibility of our newly developed phase stabilized high-speed (100 kHz A-scans/s) 1 μm sweptsource optical coherence tomography (SSOCT) system with the phase-variance based motion contrast method for visualization of human chorioretinal complex microcirculation. Compared to our previously reported spectral domain (spectrometer based) phase-variance (pv)-SDOCT system it has advantages of higher sensitivity, reduced fringe washout for high blood flow speeds and deeper penetration in choroid. High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. This process does not require additional calibration hardware and complex numerical procedures. Our phase stabilization method is simple and can be employed in a variety of SS-OCT systems. Examples of vasculature in the chorioretinal complex imaged by pv-SSOCT is presented and compared to retinal images of the same volunteers acquired with fluorescein angiography (FA) and indocyanine green angiography (ICGA).

We demonstrate the feasibility of our newly developed phase stabilized high-speed (100 kHz A-scans/s) 1 μm sweptsource optical coherence tomography (SSOCT) system with the phase-variance based motion contrast method for visualization of human chorioretinal complex microcirculation. Compared to our previously reported spectral domain (spectrometer based) phase-variance (pv)-SDOCT system it has advantages of higher sensitivity, reduced fringe washout for high blood flow speeds and deeper penetration in choroid. High phase stability SSOCT imaging was achieved by using a computationally efficient phase stabilization approach. This process does not require additional calibration hardware and complex numerical procedures. Our phase stabilization method is simple and can be employed in a variety of SS-OCT systems. Examples of vasculature in the chorioretinal complex imaged by pv-SSOCT is presented and compared to retinal images of the same volunteers acquired with fluorescein angiography (FA) and indocyanine green angiography (ICGA).

We present a new design for a reflective afocal AO-OCT retinal imaging system. The optical performance of this instrument is compared to our previous multimodal AO-OCT/AO-SLO retinal imaging system. The feasibility of new instrumentation for improved visualization of microscopic retinal structures will be discussed. Examples of images acquired with this new AO-OCT instrument will be presented. © 2013 Copyright SPIE.

Recent progress in retinal image acquisition techniques, including optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO), combined with improved performance of adaptive optics (AO) instrumentation, has resulted in improvement in the quality of in vivo images of cellular structures in the outer layers of the human retina. Despite the significant progress in imaging cone and rod photoreceptor mosaics, visualization of cellular structures in the inner retina has been achieved only with extrinsic contrast agents that have not been approved for use with humans. In this paper we describe the main limiting factors in visualizing inner retinal cells and the methods we implemented to reduce their effects on images acquired with AO-OCT. These include improving the system point spread function (AO performance), monitoring of motion artifacts (retinal motion tracking), and speckle pattern reduction (temporal and spatial averaging). Results of imaging inner retinal morphology and the improvement offered by the new UC Davis AOOCT system with spatio-temporal image averaging are presented. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

We demonstrate an intensity-based motion sensitive method, called differential logarithmic intensity variance (DLOGIV), for 3D microvasculature imaging and foveal avascular zone (FAZ) visualization in the in vivo human retina using swept source optical coherence tomog. (SS-OCT) at 1060 nm. A motion sensitive SS-OCT system was developed operating at 50,000 A-lines/s with 5.9 μm axial resoln., and used to collect 3D images over 4 mm^2 in a normal subject eye. Multiple B-scans were acquired at each individual slice through the retina and the variance of differences of logarithmic intensities as well as the differential phase variances (DPV) was calcd. to identify regions of motion (microvasculature). En face DLOGIV image were capable of capturing the microvasculature through depth with an equal performance compared to the DPV.

None of currently used tonometers produce estimated IOP values that are free of errors. Measurement incredibility arises from indirect measurement of corneal deformation and the fact that pressure calculations are based on population averaged parameters of anterior segment. Reliable IOP values are crucial for understanding and monitoring of number of eye pathologies e.g. glaucoma. We have combined high speed swept source OCT with air-puff chamber. System provides direct measurement of deformation of cornea and anterior surface of the lens. This paper describes in details the performance of air-puff ssOCT instrument. We present different approaches of data presentation and analysis. Changes in deformation amplitude appears to be good indicator of IOP changes. However, it seems that in order to provide accurate intraocular pressure values an additional information on corneal biomechanics is necessary. We believe that such information could be extracted from data provided by air-puff ssOCT.

Eye movements present during acquisition of a retinal image with optical coherence tomography (OCT) introduce motion artifacts into the image, complicating analysis and registration. This effect is especially pronounced in highresolution data sets acquired with adaptive optics (AO)-OCT instruments. Several retinal tracking systems have been introduced to correct retinal motion during data acquisition. We present a method for correcting motion artifacts in AOOCT volume data after acquisition using simultaneously captured adaptive optics-scanning laser ophthalmoscope (AOSLO) images. We extract transverse eye motion data from the AO-SLO images, assign a motion adjustment vector to each AO-OCT A-scan, and re-sample from the scattered data back onto a regular grid. The corrected volume data improve the accuracy of quantitative analyses of microscopic structures. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

We present recent developments from a phase variance based motion contrast method of retinal vascular OCT imaging, called phase variance contrast optical coherence tomography (PV-OCT). Using a 25 kHz spectral domain optical coherence tomography (SDOCT) system, the vascular visualization capabilities of this contrast method are demonstrated with composite images created from multiple data sets. Wide field vascular images extending over the fovea and optic nerve head are presented as well as microvascular retinal images over the fovea to demonstrate the trade-offs between imaging speed and vascular visualization.

Optical-resolution photoacoustic microscopy (OR-PAM) provides superb optical absorption contrast for red blood cells (RBCs), which makes it ideal for in vivo microvasculature imaging. In comparison, optical coherence tomography (OCT), widely used for tissue microstructure imaging, provides high optical scattering contrast. The two contrast mechanisms are highly complementary. In this work, we combined OR-PAM and OCT into a single, dual-modality imaging instrument for in vivo mouse eye imaging. We demonstrated in vivo dual-modality imaging of the anterior segment of mouse eyes with laser pulse energy within the ANSI laser safety standard.

An accurate solid eye model (with volumetric retinal morphology) has many applications in the field of ophthalmology, including evaluation of ophthalmic instruments and optometry/ophthalmology training. We present a method that uses volumetric OCT retinal data sets to produce an anatomically correct representation of three-dimensional (3D) retinal layers. This information is exported to a laser scan system to re-create it within solid eye retinal morphology of the eye used in OCT testing. The solid optical model eye is constructed from PMMA acrylic, with equivalent optical power to that of the human eye (∼58D). Additionally we tested a water bath eye model from Eyetech Ltd. with a customized retina consisting of five layers of ∼60 μm thick biaxial polypropylene film and hot melt rubber adhesive. © 2010 SPIE.

We describe results of retinal imaging with a novel instrument that combines adaptive optics - Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning laser ophthalmoscope (AO-SLO). One of the benefits of combining Fd-OCT with SLO includes automatic co-registration between the two imaging modalities and the potential for correcting lateral and transversal eye motion resulting in motion artifact-free volumetric retinal imaging. Additionally this allows for direct comparison between retinal structures that can be imaged with both modalities (e.g., photoreceptor mosaics or microvasculature maps). This dual imaging modality could provide insight into some retinal properties that could not be accessed by a single imaging system. Additionally, extension of OCT and SLO beyond structural imaging may open new avenues for diagnostics and testing in ophthalmology. In particular, non-invasive vasculature mapping with these modalities holds promise of replacing fluorescein angiography in vascular identification. Several new improvements of our system are described, including results of testing a novel 97-actuator deformable mirror and AO-SLO light intensity modulation. © 2010 SPIE.

We report first observations of the three-dimensional morphology of cone photoreceptors in the living human retina. Images were acquired with a high-speed adaptive optics (AO) spectral domain optical coherence tomography (SD-OCT) camera. The AO system consists of a Shack-Hartmann wavefront sensor and bimorph deformable mirror (AOptix) that measure and correct the ocular and system aberrations at a closed-loop rate of 12 Hz. Unlike previous AO-OCT and AOSLO instruments, the bimorph mirror was strategically positioned between the XY mechanical scanners and the subject's eye so as to avoid beam distortion at the pupil plane, which is created when the mirror compensates for the refractive error of the eye. This new configuration is evaluated empirically and with commercial ray tracing software. The SDOCT system consists of a superluminescent diode and a 512 pixel line scan charge-coupled device (CCD) that acquires 75,000 A-scans/sec. This rate is more than two times faster than that previously reported. Retina motion artifiacts were minimized by quickly acquiring small volume images of the retina with and without AO compensation. Camera sensitivity was sufficient to detect reflections from all major retinal layers. The distribution of bright spots observed within C-scans at the inner segment / outer segment (IS/OS) junction and at the posterior tips of the OS were found to be highly correlated with one another and with the expected cone spacing. No correlation was found between the IS/OS junction and either the plexiform layers or the layers immediately behind the OS posterior tips.

The acquisition speed of current FD-OCT (Fourier Domain - Optical Coherence Tomography) instruments allows rapid screening of three-dimensional (3D) volumes of human retinas in clinical settings. To take advantage of this ability requires software used by physicians to be capable of displaying and accessing volumetric data as well as supporting post processing in order to access important quantitative information such as thickness maps and segmented volumes. We describe our clinical FD-OCT system used to acquire 3D data from the human retina over the macula and optic nerve head. B-scans are registered to remove motion artifacts and post-processed with customized 3D visualization and analysis software. Our analysis software includes standard 3D visualization techniques along with a machine learning support vector machine (SVM) algorithm that allows a user to semi-automatically segment different retinal structures and layers. Our program makes possible measurements of the retinal layer thickness as well as volumes of structures of interest, despite the presence of noise and structural deformations associated with retinal pathology. Our software has been tested successfully in clinical settings for its efficacy in assessing 3D retinal structures in healthy as well as diseased cases. Our tool facilitates diagnosis and treatment monitoring of retinal diseases.