Dr. James A. Crowell Profile

Dr. James A. Crowell

at Indiana Univ

SPIE Involvement:

Author

Publications (17)

Proceedings Article | 13 March 2024 Presentation

In vivo AO-OCT spectral sensitivity and photopigment density measurements of human cone and rod photoreceptors

Marcel Bernucci, Yan Liu, James Crowell, Qiuzhi Ji, Donald Miller

Proceedings Volume PC12824, PC128240N (2024) https://doi.org/10.1117/12.3003331

KEYWORDS: Adaptive optics optical coherence tomography, Cones, Rods, Spectral density, In vivo imaging, Visible radiation, Video, Retina, High power lasers, Eye

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Proceedings Article | 13 March 2024 Presentation + Paper

An integrated fixation and stimulus channel for adaptive optics ophthalmoscopy with a large working distance, steering field, dioptric range, and light efficiency

Yan Liu, Marcel Bernucci, Qiuzhi Ji, James Crowell, Kristen Bowles-Johnson, Matthew Keller, Donald Miller

Proceedings Volume 12824, 1282402 (2024) https://doi.org/10.1117/12.3003262

KEYWORDS: Eye, Adaptive optics, Adaptive optics optical coherence tomography, Retina, Design, Ophthalmoscopy, Dichroic mirrors, Imaging systems

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Proceedings Article | 13 March 2024 Presentation + Paper

Method for assessing structure and function of cone photoreceptors with multiple outer segment reflections in healthy and diseased eyes

Qiuzhi Ji, Yan Liu, Marcel Bernucci, James Crowell, Donald Miller

Proceedings Volume 12824, 1282407 (2024) https://doi.org/10.1117/12.3003241

KEYWORDS: Reflection, Cones, Adaptive optics optical coherence tomography, Control systems, Retina, Spectral response, Image segmentation, Optical coherence tomography, Adaptive optics, Eye

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Proceedings Article | 5 January 2024 Open Access

Photopigment density variation of individual cone photoreceptors revealed by phase-sensitive AO-OCT (Erratum)

Marcel Bernucci, Yan Liu, James Crowell, Kazuhiro Kurokawa, Qiuzhi Ji, Donald Miller

Proceedings Volume 12360, 1236010 (2024) https://doi.org/10.1117/12.3025262

KEYWORDS: Adaptive optics optical coherence tomography, Cones, Retina

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Proceedings Article | 15 March 2023 Presentation + Paper

Low-latency, photon-efficient wavefront sensing for ultrafast adaptive optics imaging of the human retina

Yan Liu, James Crowell, Kazuhiro Kurokawa, Marcel Bernucci, Qiuzhi Ji, Ayoub Lassoued, Hae Won Jung, Donald Miller

Proceedings Volume 12360, 123600A (2023) https://doi.org/10.1117/12.2650674

KEYWORDS: Adaptive optics, Wavefront sensors, Wavefront errors, Photons, Eye, Wavefront aberrations, Cameras, Adaptive optics optical coherence tomography, Optical coherence tomography

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Proceedings Article | 15 March 2023 Presentation + Paper

S-cone identification using AO-OCT cone structural measurements and support vector machine classifier

Qiuzhi Ji, Marcel Bernucci, Yan Liu, James Crowell, Davin Miller, Donald Miller

Proceedings Volume 12360, 1236005 (2023) https://doi.org/10.1117/12.2650609

KEYWORDS: Cones, Adaptive optics optical coherence tomography, Reflection, Image segmentation, Reflectivity, Retina, Support vector machines, Eye, Adaptive optics, Video

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Proceedings Article | 15 March 2023 Presentation + Paper

Photopigment density variation of individual cone photoreceptors revealed by phase-sensitive AO-OCT

Marcel Bernucci, Yan Liu, James Crowell, Kazuhiro Kurokawa, Qiuzhi Ji, Donald Miller

Proceedings Volume 12360, 1236006 (2023) https://doi.org/10.1117/12.2649489

KEYWORDS: Cones, Adaptive optics optical coherence tomography, Spectral density, Spectral response, Histograms, Visible radiation, Retina, Retinal diseases, Resolution enhancement technologies, In vivo imaging

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Numerous retinal pathologies affect cone photoreceptor photopigment density, making it a potentially attractive functional biomarker for detecting and tracking disease progression. Conventional methods to measure photopigment density include psychophysical color matching, microspectrophotometry, and retinal densitometry, but these are either subjective, measure the aggregate response/change of thousands of cones, or are performed ex vivo. Recently, we have developed a method to measure spectral sensitivities of individual human cone photoreceptors objectively, non-invasively, and in vivo with adaptive optics optical coherence tomography (AO-OCT). In preliminary results we have observed variability in the spectral sensitivities of individual cones of the same type (S, M or L) that we hypothesize attributes to inter-cone variations in photopigment density. If correct, this may be of significant clinical interest. Here, we test this hypothesis by (1) deriving an expression for the relative photopigment densities of individual cone photoreceptors based on a theoretical model of the cone absorption process and (2) using this expression to estimate photopigment density from our AO-OCT measurements of spectral sensitivity. Our mean spectral sensitivity measurements align well to Stockman & Sharpe’s well-recognized cone fundamentals with a total least-squared error of 0.12 and confidence intervals (CI) <0.36, <0.025 and <0.017 for S, M, and L cones, respectively. The substantive variability in individual cone spectral sensitivities once related to photopigment density exhibits a distribution of standard deviation=0.177 for a group of 703 cones. This indicates a two-fold difference in light sensitivity between the least sensitive cone (least amount of photopigment) and the most sensitive cone (largest amount of photopigment) for 95% of the cones measured. Furthermore, we found relative photopigment density decreased with increasing retinal eccentricity from nasal to temporal retina at 3.8° eccentricity with a slope of -0.24/° (p < .001). Both density distribution and eccentricity dependence are consistent with the literature.

Proceedings Article | 5 March 2021 Presentation

Noninvasive method to objectively measure the spectral sensitivity of individual cone photoreceptors using AO-OCT

Marcel Bernucci, Kazuhiro Kurokawa, Furu Zhang, Yan Liu, James Crowell, Donald Miller

Proceedings Volume 11623, 1162312 (2021) https://doi.org/10.1117/12.2578429

KEYWORDS: Cones, Adaptive optics optical coherence tomography, Visible radiation, Spectral resolution, Retina, In vivo imaging, Eye, Color vision

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Proceedings Article | 5 March 2021 Presentation

Multiple-reference global registration in adaptive optics OCT retina images

Kazuhiro Kurokawa, James Crowell, Nhan Do, John Lee, Donald Miller

Proceedings Volume 11623, 116230A (2021) https://doi.org/10.1117/12.2578886

KEYWORDS: Image registration, Eye, Retina, Optical coherence tomography, Adaptive optics optical coherence tomography, Adaptive optics, Cones, Signal to noise ratio, Video, Tissues

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Proceedings Article | 5 March 2021 Presentation

Ultrafast adaptive optics for imaging the living human retina

Yan Liu, James Crowell, Kazuhiro Kurokawa, Ayoub Lassoued, Hae Won Jung, Marcel Bernucci, Donald Miller

Proceedings Volume 11623, 1162307 (2021) https://doi.org/10.1117/12.2578701

KEYWORDS: Adaptive optics

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SPIE Journal Paper | 25 January 2021 Open Access

Multi-reference global registration of individual A-lines in adaptive optics optical coherence tomography retinal images (Publisher’s Note)

Kazuhiro Kurokawa, James Crowell, Nhan Do, John Lee, Donald Miller

JBO, Vol. 26, Issue 01, 019803, (January 2021) https://doi.org/10.1117/12.10.1117/1.JBO.26.1.019803

KEYWORDS: Image registration, Adaptive optics optical coherence tomography

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SPIE Journal Paper | 6 January 2021 Open Access

Multi-reference global registration of individual A-lines in adaptive optics optical coherence tomography retinal images

Kazuhiro Kurokawa, James Crowell, Nhan Do, John Lee, Donald Miller

JBO, Vol. 26, Issue 01, 016001, (January 2021) https://doi.org/10.1117/12.10.1117/1.JBO.26.1.016001

KEYWORDS: Image registration, Eye, Adaptive optics optical coherence tomography, 3D acquisition, Cones, Detection and tracking algorithms, Video, 3D image processing, Image quality, Distortion

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Significance: Adaptive optics optical coherence tomography (AO-OCT) technology enables non-invasive, high-resolution three-dimensional (3D) imaging of the retina and promises earlier detection of ocular disease. However, AO-OCT data are corrupted by eye-movement artifacts that must be removed in post-processing, a process rendered time-consuming by the immense quantity of data. Aim: To efficiently remove eye-movement artifacts at the level of individual A-lines, including those present in any individual reference volume. Approach: We developed a registration method that cascades (1) a 3D B-scan registration algorithm with (2) a global A-line registration algorithm for correcting torsional eye movements and image scaling and generating global motion-free coordinates. The first algorithm corrects 3D translational eye movements to a single reference volume, accelerated using parallel computing. The second algorithm combines outputs of multiple runs of the first algorithm using different reference volumes followed by an affine transformation, permitting registration of all images to a global coordinate system at the level of individual A-lines. Results: The 3D B-scan algorithm estimates and corrects 3D translational motions with high registration accuracy and robustness, even for volumes containing microsaccades. Averaging registered volumes improves our image quality metrics up to 22 dB. Implementation in CUDA™ on a graphics processing unit registers a 512 × 512 × 512 volume in only 10.6 s, 150 times faster than MATLAB™ on a central processing unit. The global A-line algorithm minimizes image distortion, improves regularity of the cone photoreceptor mosaic, and supports enhanced visualization of low-contrast retinal cellular features. Averaging registered volumes improves our image quality up to 9.4 dB. It also permits extending the imaging field of view (∼2.1 × ) and depth of focus (∼5.6 × ) beyond what is attainable with single-reference registration. Conclusions: We can efficiently correct eye motion in all 3D at the level of individual A-lines using a global coordinate system.

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SPIE Journal Paper | 14 March 2020 Open Access

Suite of methods for assessing inner retinal temporal dynamics across spatial and temporal scales in the living human eye

Kazuhiro Kurokawa, James Crowell, Furu Zhang, Donald Miller

NPh, Vol. 7, Issue 01, 015013, (March 2020) https://doi.org/10.1117/12.10.1117/1.NPh.7.1.015013

KEYWORDS: Adaptive optics optical coherence tomography, Eye, Tissues, Speckle, Video, Retina, Neurophotonics, Reflectivity, Tissue optics, Optical coherence tomography

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Proceedings Article | 19 February 2020 Paper

Measuring dysfunction of cone photoreceptors in retinitis pigmentosa with phase-sensitive AO-OCT

Ayoub Lassoued, Furu Zhang, Kazuhiro Kurokawa, Yan Liu, James Crowell, Donald Miller

Proceedings Volume 11218, 1121815 (2020) https://doi.org/10.1117/12.2550216

KEYWORDS: Cones, Adaptive optics optical coherence tomography, Control systems, Optical coherence tomography, Image segmentation, Eye, Light emitting diodes, Retina, Video, Adaptive optics

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Proceedings Article | 28 February 2019 Paper

Method to track and measure loss of inner retinal neurons in the living human eye

Kazuhiro Kurokawa, Furu Zhang, James Crowell, Ayoub Lassoued, Donald Miller

Proceedings Volume 10858, 108580L (2019) https://doi.org/10.1117/12.2508909

KEYWORDS: Adaptive optics optical coherence tomography, Eye, Visualization, Neurons, Retina, Imaging systems, Optical inspection, Reflectivity, Optic nerve, Cell death

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