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Wu J. Hyperspectral imaging for non-invasive blood oxygen saturation assessment. Photodiagnosis Photodyn Ther 2024; 45:104003. [PMID: 38336148 DOI: 10.1016/j.pdpdt.2024.104003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/27/2024] [Accepted: 02/05/2024] [Indexed: 02/12/2024]
Abstract
Hyperspectral Imaging (HSI) seamlessly integrates imaging and spectroscopy, capturing both spatial and spectral data concurrently. With widespread applications in medical diagnostics, HSI serves as a noninvasive tool for gaining insights into tissue characteristics. The distinctive spectral profiles of biological tissues set HSI apart from traditional microscopy in enabling in vivo tissue analysis. Despite its potential, existing HSI techniques face challenges such as alignment issues, low light throughput, and tissue heating due to intense illumination. This study introduces an innovative HSI system featuring active sequential bandpass illumination seamlessly integrated into conventional optical instruments. The primary focus is on analyzing oxyhemoglobin and deoxyhemoglobin saturation in animal tissue samples using multivariate linear regression. This approach holds promise for enhancing noninvasive medical diagnostics. A key feature of the system, active bandpass illumination, effectively prevents tissue overheating, thereby bolstering its suitability for medical applications.
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Affiliation(s)
- Jiangbo Wu
- School of Information Science and Technology, Fudan University, Shanghai 200433, China.
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2
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Akitegetse C, Landry P, Robidoux J, Lapointe N, Brouard D, Sauvageau D. Monte-Carlo simulation and tissue-phantom model for validation of ocular oximetry. BIOMEDICAL OPTICS EXPRESS 2022; 13:2929-2946. [PMID: 35774309 PMCID: PMC9203094 DOI: 10.1364/boe.458079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 03/27/2022] [Accepted: 04/11/2022] [Indexed: 06/15/2023]
Abstract
Ocular oximetry, in which blood oxygen saturation is evaluated in retinal tissues, is a promising technique for the prevention, diagnosis and management of many diseases and conditions. However, the development of new tools for evaluating oxygen saturation in the eye fundus has often been limited by the lack of reference tools or techniques for such measurements. In this study, we describe a two-step validation method. The impact of scattering, blood volume fraction and lens yellowing on the oximetry model is investigated using a tissue phantom, while a Monte Carlo model of the light propagation in the eye fundus is used to study the effect of the fundus layered-structure. With this method, we were able to assess the performance of an ocular oximetry technique in the presence of confounding factors and to quantify the impact of the choroidal circulation on the accuracy of the measurements. The presented strategy will be useful to anyone involved in studies based on the eye fundus diffuse reflectance.
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Affiliation(s)
| | - Patricia Landry
- Affaires médicales et innovation, Héma-Québec, Québec, QC, G1V 5C3, Canada
| | - Jonathan Robidoux
- Affaires médicales et innovation, Héma-Québec, Québec, QC, G1V 5C3, Canada
| | | | - Danny Brouard
- Affaires médicales et innovation, Héma-Québec, Québec, QC, G1V 5C3, Canada
| | - Dominic Sauvageau
- Zilia inc., Québec, QC, G1K 3G5, Canada
- Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada
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3
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Khoobehi B, Wafapoor H, Eaton A, Liu R, Firn K, Kubilay T. Noninvasive Measurement of Oxygen Saturation in Human Retinal Blood Vessels and Tissues With Multispectral Confocal Imaging. Ophthalmic Surg Lasers Imaging Retina 2022; 53:275-283. [PMID: 35575738 DOI: 10.3928/23258160-20220420-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND AND OBJECTIVE Proof of concept for the first system of noninvasive human retinal vessel and tissue oxygenation measurement in axial and radial directions. MATERIALS AND METHODS A confocal imaging system capable of calculating and mapping relative retinal blood oxygenation in radial and axial directions from three eyes of two healthy subjects was built. The relationship between oxygenation and retinal depth in vivo was analyzed to illustrate application of this novel system. RESULTS The system shows capacity for measuring oxygenation along retinal depth for the first time. (1) Arteriovenous oxygenation difference decreases with blood vessel diameter. (2) Artery-tissue oxygenation difference is greater than vein-tissue oxygenation difference in the same region. (3) Intravascular-extravascular oxygenation difference decreases with blood vessel diameter. (4) Oxygenation data reported with a 95% CI are as follows: A1 91.5% ± 18.2%, V1 32.8% ± 18.6%, A2 97.3% ± 17.8%, V2 64.4% ± 11.2%, A3 73.2% ± 19.1%, V3 52.9% ± 15.3%, and Tissue 56.6% ± 00.4%. CONCLUSION This article demonstrates proof of concept for retinal oxygenation calculation in radial and axial dimensions for the first time. Initial results provide biological validity to this method. Future aims include further characterization of this system's results in healthy subjects and subsequent comparison of oxygenation between diseased and healthy retinae. [Ophthalmic Surg Lasers Imaging Retina. 2022;53:275-283.].
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In-vivo functional and structural retinal imaging using multiwavelength photoacoustic remote sensing microscopy. Sci Rep 2022; 12:4562. [PMID: 35296738 PMCID: PMC8927130 DOI: 10.1038/s41598-022-08508-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 03/08/2022] [Indexed: 11/16/2022] Open
Abstract
Many important eye diseases as well as systemic disorders manifest themselves in the retina. Retinal imaging technologies are rapidly growing and can provide ever-increasing amounts of information about the structure, function, and molecular composition of retinal tissue in-vivo. Photoacoustic remote sensing (PARS) is a novel imaging modality based on all-optical detection of photoacoustic signals, which makes it suitable for a wide range of medical applications. In this study, PARS is applied for in-vivo imaging of the retina and estimating oxygen saturation in the retinal vasculature. To our knowledge, this is the first time that a non-contact photoacoustic imaging technique is applied for in-vivo imaging of the retina. Here, optical coherence tomography is also used as a well-established retinal imaging technique to navigate the PARS imaging beams and demonstrate the capabilities of the optical imaging setup. The system is applied for in-vivo imaging of both microanatomy and the microvasculature of the retina. The developed system has the potential to advance the understanding of the ocular environment and to help in monitoring of ophthalmic diseases.
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Ivanova EV, Volodin PL, Guskov AV. Determination of Micropulse Modes with Targeted Damage to the Retinal Pigment Epithelium Using Computer Modeling for the Development of Selective Individual Micropulse Retinal Therapy. Curr Eye Res 2021; 47:107-114. [PMID: 34607475 DOI: 10.1080/02713683.2021.1962360] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE When using a serial laser system for selective impact on the retinal pigment epithelium (RPE), there is a challenge to determine the optimal range of micropulse parameters which result in targeted damage to the RPE. This study proposes a computer model that has identified the optimal parameters to be applied. METHODS This study was conducted on 18 patients who were diagnosed with acute central serous chorioretinopathy and transparent optical media, aged 35 to 46 years old, and type 2 and 3 on the Fitzpatrick scale. Testing of the micropulse mode was performed on the Navilas 577s laser system; 864 spots were analyzed in total. Considering the probability of damage visualization at different laser power, the computer simulation of tissue heating and protein denaturation was performed to determine the micropulse modes which resulted in selective damage to the RPE. RESULTS The computer model parameter ΔE = 3.34 × 105 J/mol was determined from fitting the model predictions to the autofluorescence test results. The micropulse modes with a micropulse duration of 50-100 µs, duty cycle 2.4-4.8%, 10 ms-pulse envelope (5 micropulses), and spot diameter of 100 µm have efficiency and selectivity above 67% and correspond to the optimal therapeutic window for targeted RPE damage at a certain power. Increasing the micropulse duration, number of micropulses, and duty cycle leads to a decrease in the selective effect on the RPE and higher damage to adjacent tissues. CONCLUSION The concepts of efficiency and selectivity have been introduced to quantify the amount of damage caused. The optimal range of micropulse parameters which result in effective and selective damage on the RPE has been determined for the Navilas 577s laser system. The proposed method can be used for any other serial laser system. A comparison of the different micropulse modes, as well as the CW modes, has been performed.
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Affiliation(s)
- Elena V Ivanova
- Department of Laser Retinal Surgery, Fyodorov Eye Microsurgery Federal State Institution, Moscow, Russian Federation
| | - Pavel L Volodin
- Department of Laser Retinal Surgery, Fyodorov Eye Microsurgery Federal State Institution, Moscow, Russian Federation
| | - Alexey V Guskov
- Department of Colliding Beams Physics, Joint Institute for Nuclear Research, Moscow, Russia
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Abstract
Similar to other organs, the retina relies on tightly regulated perfusion and oxygenation. Previous studies have demonstrated that retinal blood flow is affected in a variety of eye and systemic diseases, including diabetic retinopathy, age-related macular degeneration, and glaucoma. Although measurement of peripheral oxygen saturation has become a standard clinical measurement through the development of pulse oximetry, developing a noninvasive technique to measure retinal oxygen saturation has proven challenging, and retinal oximetry technology currently remains inadequate for reliable clinical use. Here, we review current strategies and approaches, as well as several newer technologies in development, and discuss the future of retinal oximetry.
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Affiliation(s)
- Anupam K Garg
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.,School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Darren Knight
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Leonardo Lando
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Daniel L Chao
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.,School of Medicine, University of California San Diego, La Jolla, CA, USA.,Janssen Research and Development, Raritan, NJ, USA
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7
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Nadal J, Deverdun J, Champfleur NM, Carriere I, Creuzot‐Garcher C, Delcourt C, Chiquet C, Kawasaki R, Villain M, Ritchie K, Le Bars E, Daien V. Retinal vascular fractal dimension and cerebral blood flow, a pilot study. Acta Ophthalmol 2020; 98:e63-e71. [PMID: 31545560 DOI: 10.1111/aos.14232] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 08/07/2019] [Indexed: 01/12/2023]
Abstract
PURPOSE Ocular and brain microcirculation share embryological and histological similarities. The retinal vascular fractal dimension (FD) is a marker of retinal vascular complexity of the vascular tree. The purpose of this study was to explore the relationship between cerebral blood flow (CBF), retinal vascular FD and other retinal vascular markers. METHODS Cross-sectional analysis comprising 26 individuals ≥65 years old from the Cognitive REServe and Clinical ENDOphenotype (CRESCENDO) cohort of relative healthy older adults. Retinal vascular FD was measured from fundus photographs by using the semi-automated Singapore Eye Vessel Assessment (SIVA) software. CBF was estimated using a 2D pulsed ASL MRI sequence. Associations between blood flow and retinal parameters were analysed using linear regression models adjusted for age and sex. RESULTS Cerebral blood flow was positively associated with venular FD (R2 = 0.32, p = 0.03). This association was stronger in the anterior versus posterior brain territories (R2 = 0.35 [p = 0.001] versus R2 = 0.16 [p = 0.07], respectively). Global CBF was correlated with arteriolar branching angle (R2 = 0.23, p = 0.01) and tortuosity (R2 = 0.20, p = 0.02). Global CBF was not correlated with other SIVA parameters. CONCLUSIONS Retinal venular complexity summarized by the FD was associated with cerebral blood flow as well as retinal arteriolar tortuosity and branching angle. Larger prospective clinical studies are needed to confirm these results.
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Affiliation(s)
- Jeremy Nadal
- Department of Ophthalmology Nîmes University Hospital Nîmes Cedex 9 France
- I2FH Institut d'Imagerie Fonctionnelle Humaine Montpellier University Hospital Center Gui de Chauliac Hospital Montpellier France
| | - Jeremy Deverdun
- I2FH Institut d'Imagerie Fonctionnelle Humaine Montpellier University Hospital Center Gui de Chauliac Hospital Montpellier France
| | - Nicolas Menjot Champfleur
- I2FH Institut d'Imagerie Fonctionnelle Humaine Montpellier University Hospital Center Gui de Chauliac Hospital Montpellier France
- Department of Neuroradiology Montpellier University Hospital Center Gui de Chauliac Hospital Montpellier France
- Laboratoire Charles Coulomb University of Montpellier Montpellier France
- Department of Medical Imaging Caremeau University Hospital Center Nimes France
| | - Isabelle Carriere
- Neuropsychiatry: Epidemiological and Clinical Research INSERM Université de Montpellier Montpellier France
| | - Catherine Creuzot‐Garcher
- Department of Ophthalmology Dijon University Hospital Dijon France
- Eye and Nutrition Research Group CSGA UMR 1324 INRA 6265 CNRS Burgundy University Dijon France
| | - Cécile Delcourt
- Bordeaux Population Health Research Center Team LEHA Inserm UMR 1219 Univ. Bordeaux Bordeaux France
| | - Christophe Chiquet
- Grenoble Alpes University Grenoble France
- Department of Ophthalmology University Hospital Grenoble France
| | - Ryo Kawasaki
- Department of Public Health Faculty of Medicine Yamagata University Yamagata Japan
- Osaka University Graduate School of Medicine Osaka Japan
| | - Max Villain
- Department of Ophthalmology Gui De Chauliac Hospital Montpellier France
| | - Karen Ritchie
- Neuropsychiatry: Epidemiological and Clinical Research INSERM Université de Montpellier Montpellier France
- Centre for Clinical Brain Sciences University of Edinburgh Edinburgh UK
| | - Emmanuelle Le Bars
- I2FH Institut d'Imagerie Fonctionnelle Humaine Montpellier University Hospital Center Gui de Chauliac Hospital Montpellier France
- Department of Neuroradiology Montpellier University Hospital Center Gui de Chauliac Hospital Montpellier France
| | - Vincent Daien
- Neuropsychiatry: Epidemiological and Clinical Research INSERM Université de Montpellier Montpellier France
- Department of Ophthalmology Gui De Chauliac Hospital Montpellier France
- The Save Sight Institute Sydney Medical School The University of Sydney Sydney NSW Australia
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8
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Convolutional Neural Networks for Spectroscopic Analysis in Retinal Oximetry. Sci Rep 2019; 9:11387. [PMID: 31388136 PMCID: PMC6684811 DOI: 10.1038/s41598-019-47621-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 06/20/2019] [Indexed: 01/06/2023] Open
Abstract
Retinal oximetry is a non-invasive technique to investigate the hemodynamics, vasculature and health of the eye. Current techniques for retinal oximetry have been plagued by quantitatively inconsistent measurements and this has greatly limited their adoption in clinical environments. To become clinically relevant oximetry measurements must become reliable and reproducible across studies and locations. To this end, we have developed a convolutional neural network algorithm for multi-wavelength oximetry, showing a greatly improved calculation performance in comparison to previously reported techniques. The algorithm is calibration free, performs sensing of the four main hemoglobin conformations with no prior knowledge of their characteristic absorption spectra and, due to the convolution-based calculation, is invariable to spectral shifting. We show, herein, the dramatic performance improvements in using this algorithm to deduce effective oxygenation (SO2), as well as the added functionality to accurately measure fractional oxygenation (\documentclass[12pt]{minimal}
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\begin{document}$${{\bf{SO}}}_{{\bf{2}}}^{{\boldsymbol{f}}{\boldsymbol{r}}}$$\end{document}SO2fr). Furthermore, this report compares, for the first time, the relative performance of several previously reported multi-wavelength oximetry algorithms in the face of controlled spectral variations. The improved ability of the algorithm to accurately and independently measure hemoglobin concentrations offers a high potential tool for disease diagnosis and monitoring when applied to retinal spectroscopy.
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Xie D, Li Q, Gao Q, Song W, Zhang HF, Yuan X. In vivo blind-deconvolution photoacoustic ophthalmoscopy with total variation regularization. JOURNAL OF BIOPHOTONICS 2018; 11:e201700360. [PMID: 29577625 DOI: 10.1002/jbio.201700360] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 03/22/2018] [Indexed: 06/08/2023]
Abstract
Photoacoustic ophthalmoscopy (PAOM) is capable of noninvasively imaging anatomic and functional information of the retina in living rodents. However, the strong ocular aberration in rodent eyes and limited ultrasonic detection sensitivity affect PAOM's spatial resolution and signal-to-noise ratio (SNR) in in vivo eyes. In this work, we report a computational approach to combine blind deconvolution (BD) algorithm with a regularizing constraint based on total variation (BDTV) for PAOM imaging restoration. We tested the algorithm in retinal and choroidal microvascular images in albino rat eyes. The algorithm improved PAOM's lateral resolution by around 2-fold. Moreover, it enabled the improvement in imaging SNR for both major vessels and capillaries, and realized the well-preserved blood vessels' edges simultaneously, which surpasses conventional Richardson-Lucy BD algorithm. The reported results indicate that the BDTV algorithm potentially facilitate PAOM in extracting retinal pathophysiological information by enhancing in vivo imaging quality without physically modifying PAOM's optical configuration.
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Affiliation(s)
- Deyan Xie
- State Key Laboratory of Integrated Services Networks, School of Telecommunications Engineering, Xidian University, Xi'an, China
| | - Qin Li
- School of Software Engineering, Shenzhen Institute of Information Technology, Shenzhen, China
| | - Quanxue Gao
- State Key Laboratory of Integrated Services Networks, School of Telecommunications Engineering, Xidian University, Xi'an, China
| | - Wei Song
- Nanophotonics Research Centre, Shenzhen University, Shenzhen, China
| | - Hao F Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois
- Department of Ophthalmology, Northwestern University, Chicago, Illinois
| | - Xiaocong Yuan
- Nanophotonics Research Centre, Shenzhen University, Shenzhen, China
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10
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Damodaran M, Amelink A, de Boer JF. Optimal wavelengths for subdiffuse scanning laser oximetry of the human retina. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-15. [PMID: 30152203 DOI: 10.1117/1.jbo.23.8.086003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 08/02/2018] [Indexed: 06/08/2023]
Abstract
Retinal blood vessel oxygenation is considered to be an important marker for numerous eye diseases. Oxygenation is typically assessed by imaging the retinal vessels at different wavelengths using multispectral imaging techniques, where the choice of wavelengths will affect the achievable measurement accuracy. Here, we present a detailed analysis of the error propagation of measurement noise in retinal oximetry, to identify optimal wavelengths that will yield the lowest uncertainty in saturation estimation for a given measurement noise level. In our analysis, we also investigate the effect of hemoglobin packing in discrete blood vessels (pigment packaging), which may result in a nonnegligible bias in saturation estimation if unaccounted for under specific geometrical conditions, such as subdiffuse sampling of smaller blood vessels located deeper within the retina. Our analyses show that using 470, 506, and 592 nm, a fairly accurate estimation of the whole oxygen saturation regime [0 1] can be realized, even in the presence of the pigment packing effect. To validate the analysis, we developed a scanning laser ophthalmoscope to produce high contrast images with a maximum pixel rate of 60 kHz and a maximum 30-deg imaging field of view. Confocal reflectance measurements were then conducted on a tissue-mimicking scattering phantom with optical properties similar to retinal tissue including narrow channels filled with absorbing dyes to mimic blood vessels. By imaging at three optimal wavelengths, the saturation of the dye combination was calculated. The experimental values show good agreement with our theoretical derivations.
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Affiliation(s)
- Mathi Damodaran
- Vrije Universiteit Amsterdam, LaserLaB, Department of Physics and Astronomy, Amsterdam, The Netherlands
| | - Arjen Amelink
- Netherlands Organisation for Applied Scientific Research TNO, Department of Optics, Delft, The Netherlands
| | - Johannes F de Boer
- Vrije Universiteit Amsterdam, LaserLaB, Department of Physics and Astronomy, Amsterdam, The Netherlands
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11
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Abramoff MD, Fort PE, Han IC, Jayasundera KT, Sohn EH, Gardner TW. Approach for a Clinically Useful Comprehensive Classification of Vascular and Neural Aspects of Diabetic Retinal Disease. Invest Ophthalmol Vis Sci 2018; 59:519-527. [PMID: 29372250 PMCID: PMC5786342 DOI: 10.1167/iovs.17-21873] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 10/08/2017] [Indexed: 11/24/2022] Open
Abstract
The Early Treatment Diabetic Retinopathy Study (ETDRS) and other standardized classification schemes have laid a foundation for tremendous advances in the understanding and management of diabetic retinopathy (DR). However, technological advances in optics and image analysis, especially optical coherence tomography (OCT), OCT angiography (OCTa), and ultra-widefield imaging, as well as new discoveries in diabetic retinal neuropathy (DRN), are exposing the limitations of ETDRS and other classification systems to completely characterize retinal changes in diabetes, which we term diabetic retinal disease (DRD). While it may be most straightforward to add axes to existing classification schemes, as diabetic macular edema (DME) was added as an axis to earlier DR classifications, doing so may make these classifications increasingly complicated and thus clinically intractable. Therefore, we propose future research efforts to develop a new, comprehensive, and clinically useful classification system that will identify multimodal biomarkers to reflect the complex pathophysiology of DRD and accelerate the development of therapies to prevent vision-threatening DRD.
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Affiliation(s)
- Michael D. Abramoff
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa, United States
- Department of Electrical and Computer Engineering, University of Iowa, Iowa City, Iowa, United States
- Iowa City VA Health Care System, Iowa City, Iowa, United States
- Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States
| | - Patrice E. Fort
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Ian C. Han
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa, United States
| | - K. Thiran Jayasundera
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States
| | - Elliott H. Sohn
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, Iowa, United States
| | - Thomas W. Gardner
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States
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Shu X, Beckmann L, Zhang HF. Visible-light optical coherence tomography: a review. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-14. [PMID: 29218923 PMCID: PMC5745673 DOI: 10.1117/1.jbo.22.12.121707] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/13/2017] [Indexed: 05/03/2023]
Abstract
Visible-light optical coherence tomography (vis-OCT) is an emerging imaging modality, providing new capabilities in both anatomical and functional imaging of biological tissue. It relies on visible light illumination, whereas most commercial and investigational OCTs use near-infrared light. As a result, vis-OCT requires different considerations in engineering design and implementation but brings unique potential benefits to both fundamental research and clinical care of several diseases. Here, we intend to provide a summary of the development of vis-OCT and its demonstrated applications. We also provide perspectives on future technology improvement and applications.
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Affiliation(s)
- Xiao Shu
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
| | - Lisa Beckmann
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
| | - Hao F. Zhang
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
- Northwestern University, Department of Ophthalmology, Chicago, Illinois, United States
- Address all correspondence to: Hao F. Zhang, E-mail:
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13
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Carles G, Muyo G, van Hemert J, Harvey AR. Combined high contrast and wide field of view in the scanning laser ophthalmoscope through dual detection of light paths. JOURNAL OF BIOMEDICAL OPTICS 2017; 22:1-10. [PMID: 29098812 DOI: 10.1117/1.jbo.22.11.116002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/11/2017] [Indexed: 06/07/2023]
Abstract
We demonstrate a multimode detection system in a scanning laser ophthalmoscope (SLO) that enables simultaneous operation in confocal, indirect, and direct modes to permit an agile trade between image contrast and optical sensitivity across the retinal field of view to optimize the overall imaging performance, enabling increased contrast in very wide-field operation. We demonstrate the method on a wide-field SLO employing a hybrid pinhole at its image plane, to yield a twofold increase in vasculature contrast in the central retina compared to its conventional direct mode while retaining high-quality imaging across a wide field of the retina, of up to 200 deg and 20 μm on-axis resolution.
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Affiliation(s)
- Guillem Carles
- University of Glasgow, School of Physics and Astronomy, Glasgow, United Kingdom
| | | | | | - Andrew R Harvey
- University of Glasgow, School of Physics and Astronomy, Glasgow, United Kingdom
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14
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Liu W, Wang S, Soetikno B, Yi J, Zhang K, Chen S, Linsenmeier RA, Sorenson CM, Sheibani N, Zhang HF. Increased Retinal Oxygen Metabolism Precedes Microvascular Alterations in Type 1 Diabetic Mice. Invest Ophthalmol Vis Sci 2017; 58:981-989. [PMID: 28535269 PMCID: PMC5308771 DOI: 10.1167/iovs.16-20600] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose To investigate inner retinal oxygen metabolic rate (IRMRO2) during early stages of type 1 diabetes in a transgenic mouse model. Methods In current study, we involved seven diabetic mice (Akita/+, TSP1−/−) and seven control mice (TSP1−/−), and applied visible-light optical coherence tomography (vis-OCT) to image functional parameters including retinal blood flow rate, oxygen saturation (sO2) and the IRMRO2 value longitudinally from 5 weeks of age to 13 weeks of age. After imaging at 13 weeks of age, we analyzed the imaging results, and examined histology of mouse retina. Results Between diabetic mice and the control group, we observed significant differences in venous sO2 from 9 weeks of age (P = 0.006), and significant increment in IRMRO2 from 11 weeks of age (P = 0.001) in diabetic mice compared with control group. We did not find significant differences in retinal blood flow rate as well as arterial sO2 during imaging between diabetic and control mice. Histologic examination of diabetic and control mice at 13 weeks of age also revealed no anatomical retinal alternations. Conclusions In diabetic retinopathy, complications in retinal oxygen metabolism may occur before changes of retinal anatomical structure.
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Affiliation(s)
- Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States
| | - Shoujian Wang
- Departments of Ophthalmology and Visual Science, University of Wisconsin, Madison, Wisconsin, United States
| | - Brian Soetikno
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States
| | - Ji Yi
- Department of Medicine, Boston University, Boston, Massachusetts, United States
| | - Kevin Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States
| | - Siyu Chen
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States
| | - Robert A Linsenmeier
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States 4Department of Ophthalmology, Northwestern University, Chicago, Illinois, United States 5Department of Neurobiology, Northwestern University, Evanston, Illinois, United States
| | - Christine M Sorenson
- Department of Pediatrics, University Wisconsin, Madison, Wisconsin, United States
| | - Nader Sheibani
- Departments of Ophthalmology and Visual Science, University of Wisconsin, Madison, Wisconsin, United States
| | - Hao F Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States 4Department of Ophthalmology, Northwestern University, Chicago, Illinois, United States
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15
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Li H, Liu W, Dong B, Kaluzny JV, Fawzi AA, Zhang HF. Snapshot hyperspectral retinal imaging using compact spectral resolving detector array. JOURNAL OF BIOPHOTONICS 2017; 10:830-839. [PMID: 27434875 PMCID: PMC5063234 DOI: 10.1002/jbio.201600053] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 05/17/2016] [Accepted: 06/14/2016] [Indexed: 05/07/2023]
Abstract
Hyperspectral retinal imaging captures the light spectrum from each imaging pixel. It provides spectrally encoded retinal physiological and morphological information, which could potentially benefit diagnosis and therapeutic monitoring of retinal diseases. The key challenges in hyperspectral retinal imaging are how to achieve snapshot imaging to avoid motions between the images from multiple spectral bands, and how to design a compact snapshot imager suitable for clinical use. Here, we developed a compact, snapshot hyperspectral fundus camera for rodents using a novel spectral resolving detector array (SRDA), on which a thin-film Fabry-Perot cavity filter was monolithically fabricated on each imaging pixel. We achieved hyperspectral retinal imaging with 16 wavelength bands (460 to 630 nm) at 20 fps. We also demonstrated false-color vessel contrast enhancement and retinal oxygen saturation (sO2 ) measurement through spectral analysis. This work could potentially bring hyperspectral retinal imaging from bench to bedside.
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Affiliation(s)
- Hao Li
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Biqin Dong
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Joel V. Kaluzny
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
| | - Amani A. Fawzi
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
- Corresponding authors: ;
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
- Corresponding authors: ;
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16
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Chen S, Shu X, Nesper PL, Liu W, Fawzi AA, Zhang HF. Retinal oximetry in humans using visible-light optical coherence tomography [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:1415-1429. [PMID: 28663838 PMCID: PMC5480553 DOI: 10.1364/boe.8.001415] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 02/01/2017] [Accepted: 02/01/2017] [Indexed: 05/18/2023]
Abstract
We measured hemoglobin oxygen saturation (sO2) in the retinal circulation in healthy humans using visible-light optical coherence tomography (vis-OCT). The measurements showed clear oxygenation differences between central retinal arteries and veins close to the optic nerve head. Spatial variations at different vascular branching levels were also revealed. In addition, we presented theoretical and experimental results to establish that noises in OCT intensity followed Rice distribution. We used this knowledge to retrieve unbiased estimation of true OCT intensity to improve the accuracy of vis-OCT oximetry, which had inherently lower signal-to-nose ratio from human eyes due to safety and comfort limitations. We demonstrated that the new statistical-fitting sampling strategy could reduce the estimation error in sO2 by three percentage points (pp). The presented work aims to provide a foundation for using vis-OCT to achieve accurate retinal oximetry in clinical settings.
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Affiliation(s)
- Siyu Chen
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Xiao Shu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Peter L. Nesper
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
| | - Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Currently with Opticent Health, Evanston, IL 60208, USA
| | - Amani A. Fawzi
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
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17
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Linsenmeier RA, Zhang HF. Retinal oxygen: from animals to humans. Prog Retin Eye Res 2017; 58:115-151. [PMID: 28109737 DOI: 10.1016/j.preteyeres.2017.01.003] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 01/13/2017] [Accepted: 01/17/2017] [Indexed: 10/20/2022]
Abstract
This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O2 in the retina: measurements of PO2 with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O2 concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO2 in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory.
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Affiliation(s)
- Robert A Linsenmeier
- Biomedical Engineering Department, Northwestern University, 2145 Sheridan Road, Evanston 60208-3107, IL, USA; Neurobiology Department, Northwestern University, 2205 Tech Drive, Evanston 60208-3520, IL, USA; Ophthalmology Department, Northwestern University, 645 N. Michigan Ave, Suite 440, Chicago 60611, IL, USA.
| | - Hao F Zhang
- Biomedical Engineering Department, Northwestern University, 2145 Sheridan Road, Evanston 60208-3107, IL, USA; Ophthalmology Department, Northwestern University, 645 N. Michigan Ave, Suite 440, Chicago 60611, IL, USA.
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18
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Kaluzny J, Li H, Liu W, Nesper P, Park J, Zhang HF, Fawzi AA. Bayer Filter Snapshot Hyperspectral Fundus Camera for Human Retinal Imaging. Curr Eye Res 2016; 42:629-635. [PMID: 27767345 DOI: 10.1080/02713683.2016.1221976] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE To demonstrate the versatility and performance of a compact Bayer filter snapshot hyperspectral fundus camera for in-vivo clinical applications including retinal oximetry and macular pigment optical density measurements. METHODS 12 healthy volunteers were recruited under an Institutional Review Board (IRB) approved protocol. Fundus images were taken with a custom hyperspectral camera with a spectral range of 460-630 nm. We determined retinal vascular oxygen saturation (sO2) for the healthy population using the captured spectra by least squares curve fitting. Additionally, macular pigment optical density was localized and visualized using multispectral reflectometry from selected wavelengths. RESULTS We successfully determined the mean sO2 of arteries and veins of each subject (ages 21-80) with excellent intrasubject repeatability (1.4% standard deviation). The mean arterial sO2 for all subjects was 90.9% ± 2.5%, whereas the mean venous sO2 for all subjects was 64.5% ± 3.5%. The mean artery-vein (A-V) difference in sO2 varied between 20.5% and 31.9%. In addition, we were able to reveal and quantify macular pigment optical density. CONCLUSIONS We demonstrated a single imaging tool capable of oxygen saturation and macular pigment density measurements in vivo. The unique combination of broad spectral range, high spectral-spatial resolution, rapid and robust imaging capability, and compact design make this system a valuable tool for multifunction spectral imaging that can be easily performed in a clinic setting.
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Affiliation(s)
- Joel Kaluzny
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Hao Li
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Peter Nesper
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Justin Park
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Hao F Zhang
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Amani A Fawzi
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
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19
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Liu W, Zhang HF. Photoacoustic imaging of the eye: A mini review. PHOTOACOUSTICS 2016; 4:112-123. [PMID: 27761410 PMCID: PMC5063360 DOI: 10.1016/j.pacs.2016.05.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 04/15/2016] [Accepted: 05/17/2016] [Indexed: 05/04/2023]
Abstract
The eye relies on the synergistic cooperation of many different ocular components, including the cornea, crystalline lens, photoreceptors, and retinal neurons, to precisely sense visual information. Complications with a single ocular component can degrade vision and sometimes cause blindness. Immediate treatment and long-term monitoring are paramount to alleviate symptoms, restore vision, and cure ocular diseases. However, successful treatment requires understanding ocular pathological mechanisms, precisely detecting and monitoring the diseases. The investigation and diagnosis of ocular diseases require advanced medical tools. In this mini review, we discuss non-invasive photoacoustic (PA) imaging as a potential research tool and medical screening device. In the research setting, PA imaging can provide valuable information on the disease progression. In the clinical setting, PA imaging can potentially aid in disease detection and treatment monitoring.
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Affiliation(s)
- Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208,USA
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208,USA
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
- Corresponding author at: Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA.
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20
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Liu W, Zhang HF. Noninvasive in vivo imaging of oxygen metabolic rate in the retina. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:3865-8. [PMID: 25570835 DOI: 10.1109/embc.2014.6944467] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Precise and noninvasive measurement of retinal oxygen metabolic rate is important for retinal pathological investigations as well as retinal disease detection, which has not been achieved until recently. Here, we quantified retinal oxygen metabolic rate in rats by combining photoacoustic ophthalmoscopy with spectral domain-optical coherence tomography. We employed multi-wavelength photoacoustic ophthalmoscopy for oxygen saturation measurement and applied dual-ring scanning Doppler spectral domain-optical coherence tomography to image retinal blood flow. With retinal oxygen saturation and blood flow being measured, we determined the retinal oxygen metabolic rate in a typical rat to be 373.41 ± 88.04 ng/minute.
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21
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Abstract
Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 μl/min during baseline and decreased to 18.7 ± 4.2 μl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 μl(O2)/min to 0.88 ± 0.14 μl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy.
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22
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Shu X, Liu W, Zhang HF. Monte Carlo investigation on quantifying the retinal pigment epithelium melanin concentration by photoacoustic ophthalmoscopy. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:106005. [PMID: 26469564 PMCID: PMC4881288 DOI: 10.1117/1.jbo.20.10.106005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 09/04/2015] [Indexed: 05/20/2023]
Abstract
The retinal pigment epithelium (RPE) melanin plays an important role in maintaining normal visual functions. A decrease in the RPE melanin concentration with aging is believed to be associated with several blinding diseases, including age-related macular degeneration. Quantifying the RPE melanin noninvasively is therefore important in evaluating the retinal health and aging conditions. Photoacoustic ophthalmoscopy (PAOM), as an optical absorption-based imaging technology, can potentially be applied to measure variations in the RPE melanin if the relationship between the detected photoacoustic (PA) signal amplitudes and the RPE melanin concentrations can be established. In this work, we tested the feasibility of using PA signals from retinal blood vessels as references to measure RPE melanin variation using Monte Carlo (MC) simulation. The influences from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness were examined. We proposed a calibration scheme by relating detected PA signals to the RPE melanin concentrations, and we found that the scheme is robust to these tested parameters. This study suggests that PAOM has the capability of quantitatively measuring the RPE melanin in vivo.
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Affiliation(s)
- Xiao Shu
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois 60208
| | - Wenzhong Liu
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois 60208
| | - Hao F. Zhang
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois 60208
- Northwestern University, Department of Ophthalmology, Chicago, Illinois 60611
- Address all correspondence to: Hao F. Zhang, E-mail:
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23
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Chen S, Yi J, Liu W, Backman V, Zhang HF. Monte Carlo Investigation of Optical Coherence Tomography Retinal Oximetry. IEEE Trans Biomed Eng 2015; 62:2308-15. [PMID: 25955984 DOI: 10.1109/tbme.2015.2424689] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Optical coherence tomography (OCT) oximetry explores the possibility to measure retinal hemoglobin oxygen saturation level (sO2). We investigated the accuracy of OCT retinal oximetry using Monte Carlo simulation in a commonly used four-layer retinal model. After we determined the appropriate number of simulated photon packets, we studied the effects of blood vessel diameter, signal sampling position, physiological sO2 level, and the blood packing factor on the accuracy of sO2 estimation in OCT retinal oximetry. The simulation results showed that a packing factor between 0.2 and 0.4 yields a reasonably accurate estimation of sO2 within a 5% error tolerance, which is independent of vessel diameter and sampling position, when visible-light illumination is used in OCT. We further explored the optimal optical spectral range for OCT retinal oximetry. The simulation results suggest that visible spectral range around 560 nm is better suited than near-infrared spectral range around 800 nm for OCT oximetry to warrant accurate measurements.
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24
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Song W, Wei Q, Liu W, Liu T, Yi J, Sheibani N, Fawzi AA, Linsenmeier RA, Jiao S, Zhang HF. A combined method to quantify the retinal metabolic rate of oxygen using photoacoustic ophthalmoscopy and optical coherence tomography. Sci Rep 2014; 4:6525. [PMID: 25283870 PMCID: PMC4185377 DOI: 10.1038/srep06525] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 09/15/2014] [Indexed: 11/25/2022] Open
Abstract
Quantitatively determining physiological parameters at a microscopic level in the retina furthers the understanding of the molecular pathways of blinding diseases, such as diabetic retinopathy and glaucoma. An essential parameter, which has yet to be quantified noninvasively, is the retinal oxygen metabolic rate (rMRO2). Quantifying rMRO2 is challenging because two parameters, the blood flow rate and hemoglobin oxygen saturation (sO2), must be measured together. We combined photoacoustic ophthalmoscopy (PAOM) with spectral domain-optical coherence tomography (SD-OCT) to tackle this challenge, in which PAOM measured the sO2 and SD-OCT mapped the blood flow rate. We tested the integrated system on normal wild-type rats, in which the measured rMRO2 was 297.86 ± 70.23 nl/minute. This quantitative method may shed new light on both fundamental research and clinical care in ophthalmology in the future.
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Affiliation(s)
- Wei Song
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Physics, Harbin Institute of Technology, 92 West Da-Zhi Street Nangang District, Harbin, Heilongjiang 150080, China
- These authors contributed equally to this work
| | - Qing Wei
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- These authors contributed equally to this work
| | - Wenzhong Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- These authors contributed equally to this work
| | - Tan Liu
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Ji Yi
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Nader Sheibani
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, WI 53792, USA
| | - Amani A. Fawzi
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
| | - Robert A. Linsenmeier
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
- Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208, USA
| | - Shuliang Jiao
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL 60611, USA
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25
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Liu T, Li H, Song W, Jiao S, Zhang HF. Fundus camera guided photoacoustic ophthalmoscopy. Curr Eye Res 2013; 38:1229-34. [PMID: 24131226 DOI: 10.3109/02713683.2013.815219] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE To demonstrate the feasibility of fundus camera guided photoacoustic ophthalmoscopy (PAOM) system and its multimodal imaging capabilities. METHODS We integrated PAOM and a fundus camera consisting of a white-light illuminator and a high-sensitivity, high-speed CCD. The fundus camera captures both retinal anatomy and PAOM illumination at the same time to provide a real-time feedback when we position the PAOM illuminating light. We applied the integrated system to image rat eyes in vivo and used full-spectrum, visible (VIS), and near infrared (NIR) illuminations in fundus photography. RESULTS Both albino and pigmented rat eyes were imaged in vivo. During alignment, different trajectories of PAOM laser scanning were successfully visualized by the fundus camera, which reduced the PAOM alignment time from several minutes to 30 s. In albino eyes, in addition to retinal vessels, main choroidal vessels were observed using VIS-illumination, which is similar to PAOM images. In pigmented eyes, the radial striations of retinal nerve fiber layer were visualized by fundus photography using full-spectrum illumination; meanwhile, PAOM imaged both retinal vessels and the retinal pigmented epithelium melanin distribution. CONCLUSIONS The results demonstrated that PAOM can be well-integrated with fundus camera without affecting its functionality. The fundus camera guidance is faster and easier comparing with our previous work. The integrated system also set the stage for the next-step verification between oximetry methods based on PAOM and fundus photography.
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Affiliation(s)
- Tan Liu
- Department of Biomedical Engineering, Northwestern University , Evanston, IL , USA
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