Mr. Qiuzhi Ji Profile

Qiuzhi Ji

at Indiana Univ.

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Author

Publications (7)

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.

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