Retinal blood flow velocity was measured in human volunteers by a high-speed adaptive optics multi-detection mode ophthalmoscope using a digital micromirror device (DMD). Retinal vascular images under multi-line illumination were captured and post-processed to obtain differential multiply scattered images with frame acquisition rate of 500 Hz. Velocity measurements based on cross-correlation or Radon transform method showed cardiac-dependent pulsatile patterns. The peak velocity was measured in the range of 1.4 mm/s to 11 mm/s depending on the vessels size. Line illumination patterns with two directions, horizontal and vertical lines, were tested to investigate the effect of relative orientation between illumination lines and vessels on contrast of moving cells.

Doppler holography uses high-speed imaging with near-infrared laser light to reveal blood flow contrasts in the eye fundus. We estimate the velocity of blood flow, blood volume rate and resistivity changes in in-plane retinal arteries by segmenting retinal vessels and calculating the local difference in root-mean-square Doppler frequency broadening compared to the background. Our approach allows for the estimation of hemodynamics in in-plane retinal arteries throughout the cardiac cycle, offering significant potential in the diagnosis and monitoring of ocular vascular conditions.

Oxygen partial pressure (pO2) has been measured in large retinal vessels using oxygen-dependent quenching of phosphorescent probe lifetimes, but existing systems face resolution or speed limitations due to camera-based or two-photon imaging. We developed a multimodal scanning laser ophthalmoscopy (SLO) and visible light optical coherence tomography (VIS-OCT) device to image murine retinae with balanced speed and resolution and capture additional vascular structure and function information. Phosphorescence intensity images using Oxyphor 2P demonstrated improved resolution, revealing smaller vascular structures, and improved throughput (~200 µs/pixel). VIS-OCT produced high resolution structural volumes and demonstrated doppler capabilities with alternating artery and vein phase shifts.

Laser Doppler holography is a technique developed to visualize blood vessels in human eye fundus and its dynamics. Quality of images obtained is compromised due to aberrations introduced by the anterior segment of the eye as well as by lenses used for viewing. As images calculated hold information about both amplitude and the phase of the field detected, the wavefront distortion can be estimated using the numerical Shack-Hartmann method in the off-line video rendering process. In result, resolution of images obtained is considerably increased and smaller blood vessels are revealed.

Epivascular microstructures, a potential biomarker for retinal diseases, are investigated in the living human retina using adaptive optics optical coherence tomography (AO-OCT). The AO correction is driven by a four-sided pyramid wavefront sensor with a loop bandwidth of 30 Hz. In order to achieve a stable placement of the focus of the imaging beam in the desired retinal layer, a new concept for focus shifting is introduced which uses an in vivo calibration routine that is performed pre-imaging in each subject. The capability of the instrument is demonstrated by visualizing hyporeflective microstructures situated along the retinal vasculature with single volume AO-OCT images recorded at an extended 4° x 4° field of view.

The ability to measure retinal blood flow (RBF) accurately and reproducibly is crucial for diagnosing and monitoring ocular diseases such as glaucoma and hypertensive retinopathy. Impaired autoregulation of blood flow plays a key role in both the development and progression of glaucoma. Multimodal adaptive optics (mAO) using scanning laser ophthalmoscopy and optical coherence tomography offer superior spatial and temporal resolution and the ability to measure blood flow in retinal microvasculature. Here we evaluate RBF measurement reproducibility and repeatability using a mAO technique.

Structural and functional dysregulation of the retinal microvasculature have been implicated in the pathogenesis of glaucomatous optic neuropathy. To detect relative blood perfusion heterogeneity in the macular circulation in subjects with glaucoma and healthy controls, we used a commercial optical coherence tomography angiography (OCTA) system with a custom post-acquisition image processing software, involving multi-volume registration and averaging. In 10 subjects diagnosed with glaucoma and 5 control subjects, we observed differences among patient groups in retinal vasculature perfusion heterogeneity, as a potential marker for vascular dysregulation.

Retinal vascular impairments, including reduced functional responsiveness, are implicated in a number of prevalent retinal disorders. Improved depth-resolved retinal vasculature imaging is possible using optical coherence tomography angiography (OCTA) after injection of a contrast agent. Flicker stimulated OCTA imaging on C57BL/6 healthy mice was performed to evaluate functional response and vascular connections with and without additional contrast. Major retinal vessels showed an increase in vessel diameter that was more pronounced in a mouse with contrast injection than in one without. Additionally, a contrast-injected mouse showed 6 times more connecting vessels overall. Contrast-enhanced OCTA may improve quantification of hemodynamics in animal models of disease.

The demand for widefield OCTA is growing as many retinal diseases exhibit alterations in the peripheral microvascular network at the early stage. In this work, we demonstrate ultrawide-field retinal OCTA over the area spanning 20 mm in diameter in 5 seconds using a 4.74 MHz A-line rate stretched-pulse mode locking (SPML)-OCT system. A concentric-circular scanning with an automatic reference arm length adjustment enabled a wide-field and large-curvature retina imaging within a 2 GHz signal bandwidth. The automatic focal plane adjustment and the deep learning-based denoising were also utilized to enhance vessel visualization in ultrawide-field OCTA images.

Quantitative assessment of retinal microvasculature in optical coherence tomography angiography (OCTA) images is important for studying, diagnosing, monitoring, and guiding the treatment of ocular and systemic diseases. However, the OCTA user community lacks harmonized image analysis tools that provide reliable and consistent microvascular metrics from diverse datasets. We present a retinal version of the OCTA vascular analyzer (OCTAVA) that addresses the challenges of robust and reproducible analysis of retinal OCTA images. We validate OCTAVA using images collected by four commercial OCTA instruments demonstrating robust performance across datasets from different instruments acquired at different sites. We show that OCTAVA characterizes retinal microvascular metrics accurately and reduces their variation between studies. By making OCTAVA publicly available, we aim to expand standardized research and improve the reproducibility of quantitative analysis of retinal microvascular imaging.

In the last quarter century, enface OCT and adaptive optics SLO imaging have exploded the ophthalmoscopic perspective, transporting clinicians through keyholes to new dimensions of retinal visualization, inviting revolutionary advances in diagnosis and therapy. To bridge the clinic - laboratory divide we have developed custom instruments to further survey and probe pathologies captured with commercial instruments, expanding our clinical understanding along with our visualization. These vistas offer a glimpse of microworlds yet to be navigated.

Cellular-resolution imaging of the living human retina requires continuous correction of blur caused by the eye’s dynamic, living optics. Over the past twenty-five years, dozens of labs have employed adaptive optics (AO) to measure and correct this blur in conjunction with retinal imaging modalities such as fundus imaging, scanning light ophthalmoscopy, and optical coherence tomography. While the benefits of AO have become more apparent, the costs of developing AO systems has not fallen substantially. A significant fraction of the cost of an AO system is development of control and analysis software. This software is typically developed by individual investigators, and represents a significant duplication of effort and grant support. Here we present an open-source AO control application and illustrate its performance in conjunction with off-the-shelf optical components.

Carotenoid macular pigments aid human vision and protect against advanced age-related macular degeneration (AMD). Recent work has shown that visible light Optical Coherence Tomography (OCT) can form depth-resolved images of macular pigments in the human retina. Here we compare superluminescent diodes (SLDs) at a range of center wavelengths from 452 nm to 637 nm to assess their suitability to visualize and quantify macular pigments. We consider light safety, ocular transmission (image signal-to-noise ratio), and macular pigment absorption contrast. We conclude that cyan and short wavelength green central wavelengths should provide a good balance of these competing considerations.

We have developed a multispectral imaging technique for identifying chemical compounds in vivo in the retina with cellular-level resolution and without the use of contrast agents. We combined simultaneous multi-channels offset and confocal AO-SLO imaging, which provides isotropic images of retinal microstructures free of directionality artifacts, with spectral signature analysis of chemical compounds to identify such biomarkers at cellular-level. The new concept has been demonstrated in a model eye using commercially available Aβ. An animal study on a mouse Alzheimer’s model is ongoing. This technique may pave a path forward for better understanding of the onset of various neurodegenerative diseases.

Acquiring OCT images from dual sample arms at the same session is helpful in applications such as multi-directional imaging (angle independent Doppler, speckle reduction), spatially multiplexed imaging (multiple fields of view or depths), and acquisition of two separate imaging fields (whole eye or binocular imaging). However, dual sampling requires complex custom control, coordination, and processing. Vortex, an open-source OCT software library has a powerful and flexible OCT framework that accommodates custom OCT acquisitions and processing as well as support for auxiliary hardware utilized in research systems. Here we use Vortex based custom software to control interleaved B-Scan level switching between anterior segment and retinal imaging with a single OCT scanner utilizing real-time independent processing of the two samples.

We demonstrate the feasibility of a multimodal AO flood-illumination ophthalmoscope, able to provide both bright-field and dark-field images. The multimodality was made possible by integrating a digital micromirror device (DMD) at the illumination path to project a sequence of complementary high-resolution patterns into the retina. Owing to the given system, and the proposed acquisition/processing pipeline, we were able, at the same time, to: (1) obtain up to four-fold contrast improvement in bright-field modality when imaging highly scattered structures such as PRs and NFL; and (2) to visualize, through phase contrast images, translucent retinal features such as capillaries, red blood cells, vessel walls, ganglion cells, and PRs inner segment.

In this work, we implement an Adaptive Optics (AO) Time-Domain Full-Field OCT (TDFFOCT) system, giving the first successful application of sensor-based adaptive optics for wavefront correction in real-time in TDFFOCT. The results demonstrate enhanced resolution and SNR after AO correction, enabling high performance in foveal imaging and also inner retina layers in proximity to the ganglion cell layer (GCL) in a wide FOV (up to 5° x 5°) without any apparent anisoplanatism.

We presented the first clinical images generated with compact, clinical-adapted FFOCT. This was made possible thanks to the replacement of the former Adaptive Lens by a Woofer-Tweeter approach, combining a Variable Focal Lens for defocus correction, and the Phaseform’s Deformable Phase Plate for high-order aberrations correction, enabling to improve both SNR and lateral resolution when imaging patients.

Recent investigations in humans have shown that rod and cone outer segments (ROS and COS, respectively) elongate in response to visual stimuli. Specifically, in phase-based optoretinographic (ORG) the relative phases of backscattered light from photoreceptors' inner segment / outer segments (IS/OS) junction and the COS tips (COST), or ROS tips (ROST), is measured, which allows observation of stimulus-evoked, nanometer-scale changes in the OS length. In this manuscript, we used a cellular resolution AO-OCT system employing an FF-SS-OCT acquisition engine that allowed up to kHz volume acquisition rates, which greatly reduced retinal motion artifacts. ORG responses were recorded in two healthy volunteers, with photopigment bleaching levels in the range of 1-60 %, and modeled using an exponential sum. The proposed harmonic oscillator-based response model allowed us to describe the shape of the cone's ORG responses by amplitudes of deflection and relaxation times. The development of simple quantitative parameters describing the ORG response should benefit future clinical applications and help to track the progress of blinding diseases.

Coarse-scale Optoretinography (CoORG) is an ORG approach that enables quick (10min), extended-field (5 deg) assessment of retinal structure and function. This study explores the feasibility of CoORG in discerning early and sensitive changes in retinitis pigmentosa (RP). In general, diminished cone function is observed in RP compared to normals using CoORG, even in areas of normal apparent outer retinal structure. This underscores the potential of CoORG for early & sensitive detection of retinal dysfunction in diseases such as RP and AMD.

Visual stimulation-induced increase in the metabolic activity of retinal neurons leads to temporary vasodilation of retinal blood vessels and an increase in the retinal blood flow, which is often referred to as functional hyperaemia. Neurodegenerative retinal diseases such as glaucoma, age-related macular degeneration, and diabetic retinopathy have been known to cause progressive damage to the retinal morphology, blood perfusion and retinal blood flow, and eventually lead to blindness. In this study, we utilize a combined OCT+ERG system to investigate functional hyperemia in the human retina.

We report Spatio-Temporal Optical Coherence Tomography (STOC-T) for acquiring optoretinography-based comprehensive characterization of retinal tissue response to flickering light across a broad spectrum (5Hz to 45Hz). This approach involves the introduction of frequency chirp during stimulation, offering a more practical means of assessing the frequency traits of photoreceptors. Our technique unveiled notable variations in response amplitudes between two subjects, both in the context of diverse stimulus amplitudes and when comparing responses to both rectangular and sinusoidal stimuli. This innovative method establishes a path for the unbiased identification of temporal-contrast sensitivity functions, exclusively focused on photoreceptors.

We present cone spectral sensitivity and photopigment density measures in the living human eye using adaptive optics optical coherence tomography (AO-OCT) and initial results in rods. AO-OCT optoretinograms after visible light stimulation of variable intensities were acquired. Cones were classified and the mean post-stimulus response to incident retinal energy and wavelength was fit to a power law and related to spectral sensitivity and photopigment density. Individual cone sensitivities showed excellent agreement with ex vivo macaque suction electrophysiology measurements (Baylor 1987). Photopigment density variation and increasing photopigment towards the fovea were consistent with the literature. Rod mean µΔOPL responses trended in the direction of expected rod sensitivity.

The biomechanical properties of the cornea are tightly linked to its structure. Refractive procedures, including laser assisted in situ keratomileusis (LASIK), can be used to correct myopia and hyperopia through precision alteration of corneal structure. However, structural alterations undoubtedly have consequences for its biomechanical integrity. Here, we utilize optical coherence elastography (OCE) to evaluate changes in corneal biomechanical properties after LASIK in ex vivo porcine corneas using three techniques, air coupled ultrasound OCE (ACUS-OCE), heartbeat OCE (Hb-OCE), and compression OCE. The results suggest that LASIK reduces tissue stiffness. Future work will examine stiffness changes in vivo.

This research uses Brillouin Microscopy and Optical Coherence Tomography (OCT) to improve our understanding of presbyopia, an age-related condition that affects near vision. Lens thickness change during accommodation and depth-dependent Brillouin shift profile were measured in vivo in 6 subjects in the age range from 21 to 54 years. We observed an age-dependent increase in lens thickness, decrease in lens thickness change and an increase in the central plateau in the Brillouin shift, consistent with previous research. We also found that the increase in the width of the plateau is associated with a decrease in the accommodative response.

Presbyopia is a loss of the dynamic accommodation response of our vision and affects everybody as they age. Despite many static corrections available, we still do not address the underlying biomechanical cause of lens stiffness. Novel lens softening therapies are limited by no ability to assess biomechanics in vivo. To address this, we developed a multimodal OCE/Brillouin system that maps spatial-varying modulus of a lens. The lens mechanical signature was measured, and a forward model was used to demonstrate the structure-function relationship of lens stiffness on clinical accommodation. This technique has the potential for patient-specific presbyopia models and therapeutic planning.

The aim of this study was to characterize the differences in corneal dynamic response in normal, forme fruste and keratoconus eyes using high-speed air-puff OCT-based optical biometry. A prototype SS-OCT optical biometer with the air-puff system was used to measure the dynamic response of the cornea to the stimulus. 50 normal eyes (NL), 15 forme fruste eyes (FFKC) and 31 eyes with early and moderate keratoconus (KC) according to the Amsler-Krumeich classification were included. The keratoconic eyes manifest significantly different air-puff induced dynamics of the cornea. However, the defined parameters did not show significant differences between NL and FFKC eyes.

Conjunctival goblet cells (CGCs) are specialized epithelial cells that secrete mucins to form the mucous layer of the protective tear film and by suppressing inflammation. Although CGCs are an important biomarker for diagnosing ocular surface diseases, rapid and noninvasive CGC examination methods have not been available. We have developed a new imaging system, high-speed extended depth-of-field wide-field microscopy with surface tracking, to enable non-contact large-area CGC imaging in human subjects. A novel long-range surface detection method was developed for rapid large-area mosaic imaging with lateral translation. Large-area CGC imaging and density quantification in human subjects was demonstrated. This new imaging system could be useful for noninvasive CGC examination in humans, which could be valuable for precision diagnosis and optimal treatment of ocular surface diseases.

Glaucoma research benefits from studying the trabecular meshwork (TM) and associated biomarkers, which is facilitated by the functional imaging of the TM motion using optical coherence tomography (OCT). Current TM measurement methods require an external cardiac pulse recording device, adding cost and complexity. Our study replaces external pulse monitoring with anterior ciliary artery (ACA) flow velocity monitoring. We implement MB mode on OCT, where the intra M-scan phase difference is to assess the ACA flow velocity, while the inter B-scan phase difference is to quantify TM motion. This cost-effective approach was successfully demonstrated on a human subject and can be readily integrated into existing clinical OCT systems, enhancing glaucoma exploration and diagnosis.

We propose a new toolset to characterize the role of corneal nerves in ocular conditions such as dry eye disease (DED). By automating analysis (nerve segmentation, density, detection of whorl patterns and nerve beading) we quantify the nerve structure over whole ex vivo corneas in a mouse model of evaporative DED. We also created a mouse line of DED with genetically encoded calcium markers and successfully imaged neural activity over time in live corneas. This combined structural and functional quantitative approach will further our understanding of corneal nerves in disease and accelerate the development of novel therapies.

The optical design of a second generation Powell Lens-based Line-Field OCT system is presented. The new design offers improved FOV, DOF and sensitivity to allow for contactless, volumetric in-vivo imaging of the human cornea. Images acquired from healthy subjects reveal the cellular structure of the corneal epithelial and endothelial layers, sub-basal and stromal nerves. The high axial resolution allows for both visualization and morphometry of the thin corneal nerves such as the endothelium, Descemet’s membrane and pre-Descemet’s (Dua) layer. Visualization of endothelial nuclei allows for fast and easy counting of endothelial cells.

Presbyopia, a decline in near vision due to aging, is primarily linked to changes in the crystalline lens. However, the ciliary muscle also contributes to this condition. Previous OCT studies focused on measuring ciliary muscle thickness at static accommodative states to understand its age-related functional response. Yet, this approach falls short in capturing the centripetal movement of the ciliary muscle towards the lens, which anatomically represents its functional response better than thickness changes. In this study, we introduce a novel method using statistical shape analysis, enabling dynamic assessment of the ciliary muscle's centripetal movement during accommodation through transscleral OCT images. This approach serves as a novel tool to explore the ciliary muscle's role in presbyopia development and optimize accommodating implant design.

This study presents a novel method for correcting aberrations and diffraction-induced artifacts in optical coherence tomography (OCT) images. The method takes advantage of light backpropagation models in combination with non-stationary despeckling and sharpness optimization algorithms to improve the overall quality of OCT images. The algorithm's application to the eye data acquired using a Powell Lens-based Line-Field OCT (PL-LF-OCT) system with a high numerical aperture (NA) and short depth-of-focus (DOF) resulted in significant enhancements in images captured at different depths. This promising improvement signifies the potential for providing ultra-high resolution volumetric OCT data without the need for depth scanning.

In-vivo imaging of the light-evoked responses of retinal cells in rodents can provide valuable insights into the correlation between optoretinography (ORG) signals and retinal degeneration. However, interpreting outer retina dynamics in rodents is challenging due to the limited resolution of optical coherence tomography, which often results in the superposition of outer retinal layers, such as the rod outer segment (ROS), retinal pigment epithelium (RPE), and Bruch’s membrane, within speckle patterns. Here, we present an automated, unbiased approach for extracting spatially-resolved outer retinal dynamics from complicated speckle patterns. Using this approach, we revealed the light-evoked dynamics of both ROS and RPE in rodents.

Adaptive optics optical coherence tomography (AO-OCT) provides state-of-the-art volumetric cellular-level imaging of the human retina in vivo. However, when coupled to AO, the OCT system's high transverse resolution reduces the depth of focus. A proven approach to this problem is acquiring AO-OCT volumes with the system focus set on different retinal layers and stitching the resulting volumes together. We demonstrate that this approach can be simplified using computational aberration correction (CAC). CAC enables us to correct AO-OCT volumes computationally in post-processing. So, we achieved an extended depth of focus without acquiring multiple AO-OCT volumes under the variable system focus settings.

Adaptive optics optical coherence tomography (AOOCT) requires a dense sampling of the retina to visualize individual cones in the living human eye. This in turn increases the acquisition time and introduces susceptibility to eye motion artifacts. Here, we present hybrid transformer generative adversarial network (HT-GAN), an artificial intelligence technique that can improve the pixel resolution of images to better reveal cones from sparsely sampled AOOCT volumes. The method can potentially increase the speed of acquisition by four-fold while maintaining the visibility of individual cones despite a lower than ideal pixel sampling.

We present deep-learning based multi-contrast optical coherence tomography (OCT) imaging methods for the analysis of retinal tissue properties. Two modalities, synthesizing degree-of-polarization-uniformity (syn-DOPU) and scatterer density estimator (SDE), were introduced. Syn-DOPU generates DOPU images from non-polarization sensitive OCT images, and hence eliminates the need for special hardware. SDE provides robust scatterer density estimation irrespective of measurement and ocular medium conditions. The methods were applied to age-related macular degeneration cases, and revealed the detailed abnormality of the retinal pigment epithelium. Additionally, layer and sector analyses of normal cases demonstrated positional and age-related variations of DOPU and scatterer density.

We demonstrate in vivo imaging with a robotically aligned OCT (RAOCT) platform that incorporates interchangeable imaging modules with integrated pupil tracking cameras. Our OCT imaging platform consisted of a fixed scan head mounted to a cooperative robot and interchangeable cornea and retinal imaging modules with their own integrated pupil cameras. We validated pupil tracking in both imaging modules (<11 µm accuracy, <±4.5 µm precision). We utilized this platform for in vivo imaging of multiple target tissues of interest in a single imaging session. This flexible design enables the ability to develop new imaging modules for new robotically aligned applications.

Microscope-integrated intraoperative optical coherence tomography (iOCT) allows for depth-resolved volumetric imaging during ophthalmic surgery. Real-time visualization of iOCT data is conventionally displayed on an external monitor or heads-up display (HUD) optically coupled to surgical oculars. Here, we demonstrate a digital micromirror device (DMD) based HUD that overcomes contrast limitations of existing intraocular HUDs. Our DMD-HUD will enable high resolution display of iOCT data and contextual overlays for real-time intraoperative feedback and during ophthalmic surgery.

Slit lamps are a common ophthalmic instrument used for examining the ocular anterior segment by projecting a rectangular beam of light onto the eye. Conventional slit lamp configurations require the patient to stabilize themselves using a chin rest and forehead band limiting access to patients who are mobility impaired. We developed a slit lamp module for a robotic arm to allow for autonomous imaging of a slit on the eye of individuals without physical head stabilization at a working distance of 125 mm. Here we describe the optical performance of the custom slit lamp module and present autonomous aligned imaging of a corneal phantom mounted in a mannequin head.

Real-time volumetric microscope-integrated OCT (MIOCT) visualization of ophthalmic surgeries is limited by the narrow field of view of OCT relative to the movement of the surgical instruments, requiring extensive manual repositioning by a trained operator. We developed a computer vision system for instrument tracking that utilizes a microscope video camera and a deep-learning object detector trained on synthetic data, which consisted of 3D rendered models of surgical instruments alongside an eye model. This system was then tested in a clinical MIOCT platform, providing high fidelity, video-rate (>40 Hz) object tracking of a cataract surgery instrument over a model eye phantom.

Compensation of ocular refractive error is essential for obtaining high-quality OCT/OCTA retinal images for retinal diagnostics across patients with different refractive power. During point-of-care ophthalmic imaging with handheld OCT systems, the clinical ergonomics of operator-driven focal adjustments to accommodate refractive error can disrupt clinical workflow. Here, we present a closed-loop automated hands-free focus tracking method to overcome limitations of conventional manual focus adjustment, and demonstrate its performance when integrated with our handheld spectrally encoded coherence tomography and reflectometry (HH-SECTR) probe. We predict automated focus tracking will improve clinical ergonomics for more efficient point-of-care ophthalmic imaging.

We developed and tested a system for measuring the through-focus point spread function (PSF) for IOLs and converting it to the modulation transfer function (MTF). The system consists of a light source, eye model, a test IOL, a 10X magnifier, and a 16-bit CCD camera. By capturing the image of the IOL through a range of focus positions, the PSF can be found and then converted to MTF. Unlike basic monofocal lenses, multifocal IOLs can focus at two or more positions, while extended depth of field (EDOF) IOLs lenses provide a continuum of foci. These advanced IOLs are beneficial as they more closely resemble the natural range of focus of the eye. The modulation transfer function (MTF) is a standard approach for IOL characterization, but existing MTF measurement methodology is not optimized for multifocal or EDOF IOLs. As IOLs continue to evolve, using the MTF to predict image quality is vital to implanting the most appropriate lens in the patient’s eyes.

Vascular retinopathy is a leading cause of preventable blindness in diabetes. While most studies focus on individual neural or vascular structures, there remains a knowledge gap in understanding the retinal neurovascular interactions due to injury and repair. We seek to demonstrate 3-D neurovascular interactions with a multi-view light-sheet imaging system. Intact 3-D retinas from 2-month-old mice were fixed and permeabilized followed by the optical clearance. Retinal vessels and neuron cells were stained with fluorescent labels. After refractive index matching, multi-view light-sheet imaging was performed at different angles followed by 3-D registration and reconstruction. This enabled 3-D co-registration of the vasculature in relation to the neuron cells for virtualization. Therefore, the 3-D neuro-microvascular network could be revealed with both deep tissue penetration and high spatial resolution for investigating hyperoxia and diabetes-associated vascular retinopathy.

Photo-mediated ultrasound therapy (PUT) is a novel antivascular therapeutic modality based on cavitation-induced bioeffects. During PUT, concurrent, synchronized laser pulses and ultrasound bursts are used to selectively and precisely remove the targeted microvessels without harming nearby tissue. In our current study, an integrated system combining PUT and spectral domain optical coherence tomography (SD-OCT) was developed, where the SD-OCT system was used to guide PUT by detecting cavitation in real time in the retina of the eye. The performance of the integrated system in treatment of choroidal microvessels was examined. The capability of detecting cavitation on a vascular-mimicking phantom was evaluated along with rabbit eyes in vivo. The findings indicate real-time OCT monitoring can improve the safety and efficiency of PUT in removing the retinal and choroidal microvasculature.

The pathophysiology of glaucoma is still unclear, and the velocity of disease progression is hard to predict. OCT allows to quantify anatomical characteristics that can be correlated with glaucoma stage, but new dynamic biomarkers based on tissue biomechanics are actively sought. However, noise in OCT images hampers the detailed analysis of time series. Here, we present a method to stabilize and denoise OCT videos using the redundancy of the data to create single heart cycle videos, which allow a precise analysis of the movement of the tissues. This approach is computationally low-cost, simple to execute and easy to implement in a clinical setting.

Several structures of the eye can be represented by established phantoms. Those are in use for research as well as training purposes. However, none of these fulfill the requirements to investigate parameters of laser surgery in the vitreous body, such as floater ablation. Here, we present means of production of a novel transparent silicone phantom, which possesses a functional lens and an adaptable vitreous body. The resulting model is highly versatile and can be used for research, training or demonstration purposes. It is easily modifiable after production, making it suitable for retina modeling as well.

We present a binocular tracking scanning laser ophthalmoscope (BTSLO), based on a line scanning ophthalmoscope configuration. BTSLO produces images of the retina of both eyes simultaneously at a framerate of up to 200 fps. These images have fields of view from 1.5º to 3º. We successfully used the system to track fixational eye movements in healthy human subjects with a sampling rate of up to 6.4kHz, and we report tracking motion of the retina at 2kHz. This is, to the best of our knowledge, the first retinal tracking system that reports these features.

We present a novel approach for spectral domain optical coherence tomography (OCT) in this proposal. Our method incorporates a depth-multiplexing strategy by utilizing multiple reference arms, each centered at different depths within the eye. By simultaneously capturing and employing phase multiplexing during post-processing, we can effectively separate the interferograms from these arms. The primary advantage of our technique lies in its ability to measure the entire eye length in a single shot, all while ensuring a cost-effective system design.

This study investigated the daily trends in the spatial and temporal heterogeneity of cone photoreceptor reflectivity. Cones contain a high density of mitochondria in their inner segments, and metabolic rates are thought to vary on a daily cycle. To test this, both eyes from ten healthy human volunteers were imaged multiple times per day (9:00am, 11:00am, 1:00pm) with an adaptive optics flood illumination camera before and after stimulation of one eye with a uniform red light, the wavelength of which is thought to promote mitochondrial metabolism. Results indicate strong statistical relationships between time of day and cone reflectivity and spatial heterogeneity. Irrespective of red light stimulus, cone reflectivity decreased by an average of 3.08 ± 3.22% in the afternoon compared to morning, and spatial heterogeneity decreased by 6.43 ± 4.51%.

We present a novel ultrafast imaging system using Spatio-Temporal Optical Coherence Tomography (STOC-T), capable of acquiring structural images of a mouse retina at a volumetric rate of 112 Hz, aided by a calibrated fundus camera for focal plane adjustment. We extract blood pulse traces from retinal and choroidal vessels using a structural-only OCT analysis, and pulse wave-induced retinal layer displacement from differential OCT phase analysis. With both analyses, we measure hemodynamic parameters, such as the delays between arterial and venous pulsation, to provide a comprehensive suite of potential biomarkers of retinal diseases.

Several important diseases and treatments of the cornea present primarily on a micromechanical level. Here, a technique called temporal phase decorrelation OCT is used to observe micromechanical weakening in the cornea after refractive surgery. This technique uses conventional OCT systems without hardware additions and may be readily adopted to enable earlier detection of disease and optimization of treatments.

This study aims to apply a dual-channel SLO for in-vivo imaging of human retinal ganglion cell (RGC) transplantation in mice. Without adaptive optics, all three vascular layers were distinctly separated by vascular fluorescent labeling, and single capillaries were clearly resolved. RGCs were derived from human embryonic cells, express RGC specific tdTomato. After 9 and 14 days of RGC transplantation in C57BL/6J wild-type and Lama1-nmf223 mice, cell survival was robust and imaged by in-vivo SLO. Most RGC cells were found gathering near optic nerve head and grew extensive and lengthy neurites. Thus, our system can serve as a non-invasive tool for in-vivo monitoring of RGC repopulation.

Electromechanical reshaping (EMR) has the potential to change corneal shape to correct refractive errors without altering the mechanical properties of the cornea. Using acoustic radiation force (ARF) to stimulate the cornea of ex vivo New Zealand white rabbit globes and optical coherence elastography (OCE) to detect corneal response, the cornea’s elasticity was quantitatively determined pre- and post-EMR treatment. In addition, an optical coherence tomography (OCT) system was used to determine changes in corneal curvature. Ultimately, EMR treatment induced a shape change in the cornea and the elasticity of the cornea was similar before and after EMR treatment, indicating minimal damage.