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Lee S, Choi SS, Meleppat RK, Zawadzki RJ, Doble N. High-speed, phase contrast retinal and blood flow imaging using an adaptive optics partially confocal multi-line ophthalmoscope. BIOMEDICAL OPTICS EXPRESS 2024; 15:1815-1830. [PMID: 38495707 PMCID: PMC10942708 DOI: 10.1364/boe.507449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/18/2023] [Accepted: 01/14/2024] [Indexed: 03/19/2024]
Abstract
High-speed, phase contrast retinal and blood flow imaging using an adaptive optics partially confocal multi-line ophthalmosocope (AO-pcMLO) is described. It allows for simultaneous confocal and phase contrast imaging with various directional multi-line illumination by using a single 2D camera and a digital micromirror device (DMD). Both vertical and horizontal line illumination directions were tested, for photoreceptor and vascular imaging. The phase contrast imaging provided improved visualization of retinal structures such as cone inner segments, vessel walls and red blood cells with images being acquired at frame rates up to 500 Hz. Blood flow velocities of small vessels (<40 µm in diameter) were measured using kymographs for capillaries and cross-correlation between subsequent images for arterioles or venules. Cardiac-related pulsatile patterns were observed with normal resting heart-beat rate, and instantaneous blood flow velocities from 0.7 to 20 mm/s were measured.
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Affiliation(s)
- Soohyun Lee
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, Ohio 43210, USA
| | - Stacey S. Choi
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, Ohio 43210, USA
- Department of Ophthalmology and Visual Sciences, Havener Eye Institute, The Ohio State University, 915 Olentangy River Road, Suite 5000, Ohio 43212, USA
| | - Ratheesh K. Meleppat
- UC Davis Eye Center, Department of Ophthalmology and Vision Science, University of California, Davis, 4860 Y Street, Suite 2400, Sacramento, California 95817, USA
- UC Davis EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California, Davis, 4320 Tupper Hall, Davis, California 95616, USA
| | - Robert J. Zawadzki
- UC Davis Eye Center, Department of Ophthalmology and Vision Science, University of California, Davis, 4860 Y Street, Suite 2400, Sacramento, California 95817, USA
- UC Davis EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California, Davis, 4320 Tupper Hall, Davis, California 95616, USA
| | - Nathan Doble
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, Ohio 43210, USA
- Department of Ophthalmology and Visual Sciences, Havener Eye Institute, The Ohio State University, 915 Olentangy River Road, Suite 5000, Ohio 43212, USA
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Mujat M, Sampani K, Patel AH, Zambrano R, Sun JK, Wollstein G, Ferguson RD, Schuman JS, Iftimia N. Motion Contrast, Phase Gradient, and Simultaneous OCT Images Assist in the Interpretation of Dark-Field Images in Eyes with Retinal Pathology. Diagnostics (Basel) 2024; 14:184. [PMID: 38248061 PMCID: PMC10814023 DOI: 10.3390/diagnostics14020184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 01/04/2024] [Accepted: 01/08/2024] [Indexed: 01/23/2024] Open
Abstract
The cellular-level visualization of retinal microstructures such as blood vessel wall components, not available with other imaging modalities, is provided with unprecedented details by dark-field imaging configurations; however, the interpretation of such images alone is sometimes difficult since multiple structural disturbances may be present in the same time. Particularly in eyes with retinal pathology, microstructures may appear in high-resolution retinal images with a wide range of sizes, sharpnesses, and brightnesses. In this paper we show that motion contrast and phase gradient imaging modalities, as well as the simultaneous acquisition of depth-resolved optical coherence tomography (OCT) images, provide additional insight to help understand the retinal neural and vascular structures seen in dark-field images and may enable improved diagnostic and treatment plans.
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Affiliation(s)
- Mircea Mujat
- Physical Sciences, Inc., 20 New England Business Center, Andover, MA 01810, USA; (A.H.P.); (R.D.F.); (N.I.)
| | - Konstantina Sampani
- Beetham Eye Institute, Joslin Diabetes Center, Boston, MA 02115, USA; (K.S.); (J.K.S.)
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Ankit H. Patel
- Physical Sciences, Inc., 20 New England Business Center, Andover, MA 01810, USA; (A.H.P.); (R.D.F.); (N.I.)
| | - Ronald Zambrano
- Department of Ophthalmology, New York University School of Medicine, New York, NY 10017, USA; (R.Z.); (G.W.)
| | - Jennifer K. Sun
- Beetham Eye Institute, Joslin Diabetes Center, Boston, MA 02115, USA; (K.S.); (J.K.S.)
- Department of Ophthalmology, Harvard Medical School, Boston, MA 02115, USA
| | - Gadi Wollstein
- Department of Ophthalmology, New York University School of Medicine, New York, NY 10017, USA; (R.Z.); (G.W.)
| | - R. Daniel Ferguson
- Physical Sciences, Inc., 20 New England Business Center, Andover, MA 01810, USA; (A.H.P.); (R.D.F.); (N.I.)
| | | | - Nicusor Iftimia
- Physical Sciences, Inc., 20 New England Business Center, Andover, MA 01810, USA; (A.H.P.); (R.D.F.); (N.I.)
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Mujat M, Akula JD, Fulton AB, Ferguson RD, Iftimia N. Non-Rigid Registration for High-Resolution Retinal Imaging. Diagnostics (Basel) 2023; 13:2285. [PMID: 37443679 PMCID: PMC10341150 DOI: 10.3390/diagnostics13132285] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/15/2023] Open
Abstract
Adaptive optics provides improved resolution in ophthalmic imaging when retinal microstructures need to be identified, counted, and mapped. In general, multiple images are averaged to improve the signal-to-noise ratio or analyzed for temporal dynamics. Image registration by cross-correlation is straightforward for small patches; however, larger images require more sophisticated registration techniques. Strip-based registration has been used successfully for photoreceptor mosaic alignment in small patches; however, if the deformations along strips are not simple displacements, averaging can degrade the final image. We have applied a non-rigid registration technique that improves the quality of processed images for mapping cones over large image patches. In this approach, correction of local deformations compensates for local image stretching, compressing, bending, and twisting due to a number of causes. The main result of this procedure is improved definition of retinal microstructures that can be better identified and segmented. Derived metrics such as cone density, wall-to-lumen ratio, and quantification of structural modification of blood vessel walls have diagnostic value in many retinal diseases, including diabetic retinopathy and age-related macular degeneration, and their improved evaluations may facilitate early diagnostics of retinal diseases.
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Affiliation(s)
- Mircea Mujat
- Physical Sciences, Inc., 20 New England Business Center, Andover, MA 01810, USA; (R.D.F.); (N.I.)
| | - James D. Akula
- Department of Ophthalmology, Boston Children’s Hospital, Boston, MA 02115, USA; (J.D.A.); (A.B.F.)
- Department of Ophthalmology, Harvard Medical School, Boston, MA 02115, USA
| | - Anne B. Fulton
- Department of Ophthalmology, Boston Children’s Hospital, Boston, MA 02115, USA; (J.D.A.); (A.B.F.)
- Department of Ophthalmology, Harvard Medical School, Boston, MA 02115, USA
| | - R. Daniel Ferguson
- Physical Sciences, Inc., 20 New England Business Center, Andover, MA 01810, USA; (R.D.F.); (N.I.)
| | - Nicusor Iftimia
- Physical Sciences, Inc., 20 New England Business Center, Andover, MA 01810, USA; (R.D.F.); (N.I.)
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Young LK, Smithson HE. Emulated retinal image capture (ERICA) to test, train and validate processing of retinal images. Sci Rep 2021; 11:11225. [PMID: 34045507 PMCID: PMC8160341 DOI: 10.1038/s41598-021-90389-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 05/04/2021] [Indexed: 12/13/2022] Open
Abstract
High resolution retinal imaging systems, such as adaptive optics scanning laser ophthalmoscopes (AOSLO), are increasingly being used for clinical research and fundamental studies in neuroscience. These systems offer unprecedented spatial and temporal resolution of retinal structures in vivo. However, a major challenge is the development of robust and automated methods for processing and analysing these images. We present ERICA (Emulated Retinal Image CApture), a simulation tool that generates realistic synthetic images of the human cone mosaic, mimicking images that would be captured by an AOSLO, with specified image quality and with corresponding ground-truth data. The simulation includes a self-organising mosaic of photoreceptors, the eye movements an observer might make during image capture, and data capture through a real system incorporating diffraction, residual optical aberrations and noise. The retinal photoreceptor mosaics generated by ERICA have a similar packing geometry to human retina, as determined by expert labelling of AOSLO images of real eyes. In the current implementation ERICA outputs convincingly realistic en face images of the cone photoreceptor mosaic but extensions to other imaging modalities and structures are also discussed. These images and associated ground-truth data can be used to develop, test and validate image processing and analysis algorithms or to train and validate machine learning approaches. The use of synthetic images has the advantage that neither access to an imaging system, nor to human participants is necessary for development.
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Affiliation(s)
- Laura K Young
- Biosciences Institute, Newcastle University, Newcastle, NE2 4HH, UK.
| | - Hannah E Smithson
- Department of Experimental Psychology, University of Oxford, Oxford, OX2 6GG, UK
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Kalra G, Pichi F, Kumar Menia N, Shroff D, Phasukkijwatana N, Aggarwal K, Agarwal A. Recent advances in wide field and ultrawide field optical coherence tomography angiography in retinochoroidal pathologies. Expert Rev Med Devices 2021; 18:375-386. [PMID: 33724126 DOI: 10.1080/17434440.2021.1902301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Introduction: With the advent of wide field (WF) and ultra-wide field (UWF) imaging in color fundus photography and fluorescein angiography (FA), the importance of an expanded field-of-view (FOV) has been illustrated for early detection of several chorioretinal disorders. The need to bring similar utility to optical coherence tomography angiography (OCTA) is imperative.Areas covered: For this review, we explored all research items with WF or UWF on Pubmed Central and Google Scholar. Software-based methods included algorithms for motion correction, artifact reduction, image pre-processing, post-processing and montage protocols while hardware methods included swept-source OCTA, faster scanning sources, hardware-based motion tracking and image registration, scanning sources with faster speeds and lower resolution. For various disorders such as diabetic retinopathy, uveitis, vascular disorders, among others, the increased FOV showed demonstrably increased detection rates and diagnostic yield.Expert opinion: Increased FOV in OCTA imaging is a meaningful and impactful step in ophthalmic imaging. Overcoming the hardware-based limitations can potentially yield higher FOV without loss of important details. In addition to improvements in the hardware and available equipment, better software tools and image processing algorithms may greatly enhance the utility of UWF OCTA in care of patients with various retinochoroidal diseases.
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Affiliation(s)
- Gagan Kalra
- Advanced Eye Center, Department of Ophthalmology, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Francesco Pichi
- Eye Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates.,Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Nitin Kumar Menia
- Advanced Eye Center, Department of Ophthalmology, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Daraius Shroff
- Shroff Eye Center, Department of Vitreoretina and Uveitis, New Delhi, India
| | | | - Kanika Aggarwal
- Advanced Eye Center, Department of Ophthalmology, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Aniruddha Agarwal
- Advanced Eye Center, Department of Ophthalmology, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
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Luo T, Warner RL, Sapoznik KA, Walker BR, Burns SA. Template free eye motion correction for scanning systems. OPTICS LETTERS 2021; 46:753-756. [PMID: 33577506 PMCID: PMC8447858 DOI: 10.1364/ol.415285] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 12/31/2020] [Indexed: 05/18/2023]
Abstract
Scanning imaging systems are susceptible to image warping in the presence of target motion occurring within the time required to acquire an individual image frame. In this Letter, we introduce the use of a dual raster scanning approach to correct for motion distortion without the need for prior knowledge of the undistorted image. In the dual scanning approach, the target is imaged simultaneously with two imaging beams from the same imaging system. The two imaging beams share a common pupil but have a spatial shift between the beams on the imaging plane. The spatial shift can be used to measure high speed events, because it measures an identical region at two different times within the time required for acquisition of a single frame. In addition, it provides accurate spatial information, since two different regions on the target are imaged simultaneously, providing an undistorted estimate of the spatial relation between regions. These spatial and temporal relations accurately measure target motion. Data from adaptive optics scanning laser ophthalmoscope (AOSLO) imaging of the human retina are used to demonstrate this technique. We apply the technique to correct the shearing of retinal images produced by eye motion. Three control subjects were measured while imaging different retinal layers and retinal locations to qualify the effectiveness of the algorithm. Since the time shift between channels is readily adjustable, this method can be tuned to match different imaging situations. The major requirement is the need to separate the two images; in our case, we used different near infrared spectral regions and dichroic filters.
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Affiliation(s)
- Ting Luo
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
| | - Raymond L. Warner
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
| | - Kaitlyn A Sapoznik
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
| | - Brittany R. Walker
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
| | - Stephen A. Burns
- Optometry School, Indiana University Bloomington, 800 Atwater Ave., Bloomington, IN 47045
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Burns SA, Elsner AE, Sapoznik KA, Warner RL, Gast TJ. Adaptive optics imaging of the human retina. Prog Retin Eye Res 2019; 68:1-30. [PMID: 30165239 PMCID: PMC6347528 DOI: 10.1016/j.preteyeres.2018.08.002] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/22/2018] [Accepted: 08/24/2018] [Indexed: 12/18/2022]
Abstract
Adaptive Optics (AO) retinal imaging has provided revolutionary tools to scientists and clinicians for studying retinal structure and function in the living eye. From animal models to clinical patients, AO imaging is changing the way scientists are approaching the study of the retina. By providing cellular and subcellular details without the need for histology, it is now possible to perform large scale studies as well as to understand how an individual retina changes over time. Because AO retinal imaging is non-invasive and when performed with near-IR wavelengths both safe and easily tolerated by patients, it holds promise for being incorporated into clinical trials providing cell specific approaches to monitoring diseases and therapeutic interventions. AO is being used to enhance the ability of OCT, fluorescence imaging, and reflectance imaging. By incorporating imaging that is sensitive to differences in the scattering properties of retinal tissue, it is especially sensitive to disease, which can drastically impact retinal tissue properties. This review examines human AO retinal imaging with a concentration on the use of the Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO). It first covers the background and the overall approaches to human AO retinal imaging, and the technology involved, and then concentrates on using AO retinal imaging to study the structure and function of the retina.
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Affiliation(s)
- Stephen A Burns
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States.
| | - Ann E Elsner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Kaitlyn A Sapoznik
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Raymond L Warner
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
| | - Thomas J Gast
- 800E. Atwater S, School of Optometry, Indiana University, Bloomington, IN, United States
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Lu J, Gu B, Wang X, Zhang Y. High speed adaptive optics ophthalmoscopy with an anamorphic point spread function. OPTICS EXPRESS 2018; 26:14356-14374. [PMID: 29877476 PMCID: PMC6005671 DOI: 10.1364/oe.26.014356] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 05/11/2018] [Indexed: 05/04/2023]
Abstract
Retinal imaging working with a line scan mechanism and a line camera has the potential to image the eye with a near-confocal performance at the high frame rate, but this regime has difficulty to collect sufficient imaging light while adequately digitize the optical resolution in adaptive optics imaging. To meet this challenge, we have developed an adaptive optics line scan ophthalmoscope with an anamorphic point spread function. The instrument uses a high-speed line camera to acquire the retinal image and act as a confocal gate. Meanwhile, it employs a digital micro-mirror device to modulate the imaging light into a line of point sources illuminating the retina. The anamorphic mechanism ensures adequate digitization of the optical resolution and increases light collecting efficiency. We demonstrate imaging of the living human retina with cellular level resolution at a frame rate of 200 frames/second (FPS) with a digitization of 512 × 512 pixels over a field of view of 1.2° × 1.2°. We have assessed cone photoreceptor structure in images acquired at 100, 200, and 800 FPS in 2 normal human subjects, and confirmed that retinal images acquired at high speed rendered macular cone mosaic with improved measurement repeatability.
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Litts KM, Cooper RF, Duncan JL, Carroll J. Photoreceptor-Based Biomarkers in AOSLO Retinal Imaging. Invest Ophthalmol Vis Sci 2017; 58:BIO255-BIO267. [PMID: 28873135 PMCID: PMC5584616 DOI: 10.1167/iovs.17-21868] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 07/28/2017] [Indexed: 01/08/2023] Open
Abstract
Improved understanding of the mechanisms underlying inherited retinal degenerations has created the possibility of developing much needed treatments for these relentless, blinding diseases. However, standard clinical indicators of retinal health (such as visual acuity and visual field sensitivity) are insensitive measures of photoreceptor survival. In many retinal degenerations, significant photoreceptor loss must occur before measurable differences in visual function are observed. Thus, there is a recognized need for more sensitive outcome measures to assess therapeutic efficacy as numerous clinical trials are getting underway. Adaptive optics (AO) retinal imaging techniques correct for the monochromatic aberrations of the eye and can be used to provide nearly diffraction-limited images of the retina. Many groups routinely are using AO imaging tools to obtain in vivo images of the rod and cone photoreceptor mosaic, and it now is possible to monitor photoreceptor structure over time with single cell resolution. Highlighting recent work using AO scanning light ophthalmoscopy (AOSLO) across a range of patient populations, we review the development of photoreceptor-based metrics (e.g., density/geometry, reflectivity, and size) as candidate biomarkers. Going forward, there is a need for further development of automated tools and normative databases, with the latter facilitating the comparison of data sets across research groups and devices. Ongoing and future clinical trials for inherited retinal diseases will benefit from the improved resolution and sensitivity that multimodal AO retinal imaging affords to evaluate safety and efficacy of emerging therapies.
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Affiliation(s)
- Katie M. Litts
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Robert F. Cooper
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Jacque L. Duncan
- Department of Ophthalmology, University of California, San Francisco, California, United States
| | - Joseph Carroll
- Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
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Salmon AE, Cooper RF, Langlo CS, Baghaie A, Dubra A, Carroll J. An Automated Reference Frame Selection (ARFS) Algorithm for Cone Imaging with Adaptive Optics Scanning Light Ophthalmoscopy. Transl Vis Sci Technol 2017; 6:9. [PMID: 28392976 PMCID: PMC5381332 DOI: 10.1167/tvst.6.2.9] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 02/28/2017] [Indexed: 01/12/2023] Open
Abstract
PURPOSE To develop an automated reference frame selection (ARFS) algorithm to replace the subjective approach of manually selecting reference frames for processing adaptive optics scanning light ophthalmoscope (AOSLO) videos of cone photoreceptors. METHODS Relative distortion was measured within individual frames before conducting image-based motion tracking and sorting of frames into distinct spatial clusters. AOSLO images from nine healthy subjects were processed using ARFS and human-derived reference frames, then aligned to undistorted AO-flood images by nonlinear registration and the registration transformations were compared. The frequency at which humans selected reference frames that were rejected by ARFS was calculated in 35 datasets from healthy subjects, and subjects with achromatopsia, albinism, or retinitis pigmentosa. The level of distortion in this set of human-derived reference frames was assessed. RESULTS The average transformation vector magnitude required for registration of AOSLO images to AO-flood images was significantly reduced from 3.33 ± 1.61 pixels when using manual reference frame selection to 2.75 ± 1.60 pixels (mean ± SD) when using ARFS (P = 0.0016). Between 5.16% and 39.22% of human-derived frames were rejected by ARFS. Only 2.71% to 7.73% of human-derived frames were ranked in the top 5% of least distorted frames. CONCLUSION ARFS outperforms expert observers in selecting minimally distorted reference frames in AOSLO image sequences. The low success rate in human frame choice illustrates the difficulty in subjectively assessing image distortion. TRANSLATIONAL RELEVANCE Manual reference frame selection represented a significant barrier to a fully automated image-processing pipeline (including montaging, cone identification, and metric extraction). The approach presented here will aid in the clinical translation of AOSLO imaging.
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Affiliation(s)
- Alexander E Salmon
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Robert F Cooper
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA ; Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, USA
| | - Christopher S Langlo
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Ahmadreza Baghaie
- Department of Electrical Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Alfredo Dubra
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA ; Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA ; Current affiliation: Department of Ophthalmology, Stanford University, 2452 Watson Court, Palo Alto, CA, USA
| | - Joseph Carroll
- Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA ; Department of Ophthalmology & Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA
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Liu C, Thapa D, Yao X. Digital adaptive optics confocal microscopy based on iterative retrieval of optical aberration from a guidestar hologram. OPTICS EXPRESS 2017; 25:8223-8236. [PMID: 28380937 PMCID: PMC5810909 DOI: 10.1364/oe.25.008223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/07/2017] [Accepted: 03/13/2017] [Indexed: 06/07/2023]
Abstract
Guidestar hologram based digital adaptive optics (DAO) is one recently emerging active imaging modality. It records each complex distorted line field reflected or scattered from the sample by an off-axis digital hologram, measures the optical aberration from a separate off-axis digital guidestar hologram, and removes the optical aberration from the distorted line fields by numerical processing. In previously demonstrated DAO systems, the optical aberration was directly retrieved from the guidestar hologram by taking its Fourier transform and extracting the phase term. For the direct retrieval method (DRM), when the sample is not coincident with the guidestar focal plane, the accuracy of the optical aberration retrieved by DRM undergoes a fast decay, leading to quality deterioration of corrected images. To tackle this problem, we explore here an image metrics-based iterative method (MIM) to retrieve the optical aberration from the guidestar hologram. Using an aberrated objective lens and scattering samples, we demonstrate that MIM can improve the accuracy of the retrieved aberrations from both focused and defocused guidestar holograms, compared to DRM, to improve the robustness of the DAO.
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Affiliation(s)
- Changgeng Liu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Damber Thapa
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Xincheng Yao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
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12
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Lu J, Gu B, Wang X, Zhang Y. High-speed adaptive optics line scan confocal retinal imaging for human eye. PLoS One 2017; 12:e0169358. [PMID: 28257458 PMCID: PMC5336222 DOI: 10.1371/journal.pone.0169358] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 12/15/2016] [Indexed: 01/03/2023] Open
Abstract
Purpose Continuous and rapid eye movement causes significant intraframe distortion in adaptive optics high resolution retinal imaging. To minimize this artifact, we developed a high speed adaptive optics line scan confocal retinal imaging system. Methods A high speed line camera was employed to acquire retinal image and custom adaptive optics was developed to compensate the wave aberration of the human eye’s optics. The spatial resolution and signal to noise ratio were assessed in model eye and in living human eye. The improvement of imaging fidelity was estimated by reduction of intra-frame distortion of retinal images acquired in the living human eyes with frame rates at 30 frames/second (FPS), 100 FPS, and 200 FPS. Results The device produced retinal image with cellular level resolution at 200 FPS with a digitization of 512×512 pixels/frame in the living human eye. Cone photoreceptors in the central fovea and rod photoreceptors near the fovea were resolved in three human subjects in normal chorioretinal health. Compared with retinal images acquired at 30 FPS, the intra-frame distortion in images taken at 200 FPS was reduced by 50.9% to 79.7%. Conclusions We demonstrated the feasibility of acquiring high resolution retinal images in the living human eye at a speed that minimizes retinal motion artifact. This device may facilitate research involving subjects with nystagmus or unsteady fixation due to central vision loss.
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Affiliation(s)
- Jing Lu
- Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Boyu Gu
- Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Xiaolin Wang
- Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Yuhua Zhang
- Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail:
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Liu C, Cao H, Choma MA. Coherent artifact suppression in line-field reflection confocal microscopy using a low spatial coherence light source. OPTICS LETTERS 2016; 41:4775-4778. [PMID: 28005890 DOI: 10.1364/ol.41.004775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Line-field reflection confocal microscopy (LF-RCM) has the potential to add a dimension of parallelization to traditional confocal microscopy while reducing the need for two-axis beam scanning. LF-RCM systems often employ light sources with a high degree of spatial coherence. This high degree of spatial coherence potentially leads to unwanted coherent artifact in the setting of nontrivial sample scattering. Here, we (a) confirm that a coherent artifact is a nontrivial problem in LF-RCM when using spatially coherent light, and (b) demonstrate that such a coherent artifact can be mitigated through the use of reduced spatial coherence line-field sources. We demonstrate coherent noise suppression in a full-pupil line-field confocal microscope using a large number of mutually incoherent emitters from a vertical-cavity surface-emitting lasers (VCSEL) array. The coherent noise from a highly scattering sample is significantly suppressed by the use of this synthesized reduced spatial coherence light source compared to a fully coherent light source. Lastly, with scattering samples, the axial confocality of line-field confocal microscopy is compromised independent of the source spatial coherence, as demonstrated by our experimental result. Our results highlight the importance of spatial coherence engineering in parallelized reflection confocal microscopy.
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Lu J, Gu B, Wang X, Zhang Y. Adaptive optics parallel near-confocal scanning ophthalmoscopy. OPTICS LETTERS 2016; 41:3852-5. [PMID: 27519106 PMCID: PMC5218998 DOI: 10.1364/ol.41.003852] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We present an adaptive optics parallel near-confocal scanning ophthalmoscope (AOPCSO) using a digital micromirror device (DMD). The imaging light is modulated to be a line of point sources by the DMD, illuminating the retina simultaneously. By using a high-speed line camera to acquire the image and using adaptive optics to compensate the ocular wave aberration, the AOPCSO can image the living human eye with cellular level resolution at the frame rate of 100 Hz. AOPCSO has been demonstrated with improved spatial resolution in imaging of the living human retina compared with adaptive optics line scan ophthalmoscopy.
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15
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Liu C, Knitter S, Cong Z, Sencan I, Cao H, Choma MA. High-speed line-field confocal holographic microscope for quantitative phase imaging. OPTICS EXPRESS 2016; 24:9251-65. [PMID: 27137541 PMCID: PMC5025226 DOI: 10.1364/oe.24.009251] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/10/2016] [Accepted: 04/11/2016] [Indexed: 05/22/2023]
Abstract
We present a high-speed and phase-sensitive reflectance line-scanning confocal holographic microscope (LCHM). We achieved rapid confocal imaging using a fast line-scan CCD camera and quantitative phase imaging using off-axis digital holography (DH) on a 1D, line-by-line basis in our prototype experiment. Using a 20 kHz line scan rate, we achieved a frame rate of 20 Hz for 512x512 pixels en-face confocal images. We realized coherent holographic detection two different ways. We first present a LCHM using off-axis configuration. By using a microscope objective of a NA 0.65, we achieved axial and lateral resolution of ~3.5 micrometers and ~0.8 micrometers, respectively. We demonstrated surface profile measurement of a phase target at nanometer precision and the digital refocusing of a defocused confocal en-face image. Ultrahigh temporal resolution M mode is demonstrated by measuring the vibration of a PZT-actuated mirror driven by a sine wave at 1 kHz. We then report our experimental work on a LCHM using an in-line configuration. In this in-line LCHM, the coherent detection is enabled by moving the reference arm at a constant speed, thereby introducing a Doppler frequency shift that leads to spatial interference fringes along the scanning direction. Lastly, we present a unified formulation that treats off-axis and in-line LCHM in a unified joint spatiotemporal modulation framework and provide a connection between LCHM and the traditional off-axis DH. The presented high-speed LCHM may find applications in optical metrology and biomedical imaging.
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Affiliation(s)
- Changgeng Liu
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut 06520,
USA
| | - Sebastian Knitter
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520,
USA
| | - Zhilong Cong
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut 06520,
USA
| | - Ikbal Sencan
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut 06520,
USA
| | - Hui Cao
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520,
USA
| | - Michael A. Choma
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut 06520,
USA
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520,
USA
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut 06520,
USA
- Department of Pediatrics, Yale School of Medicine, New Haven, Connecticut 06520,
USA
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16
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Salas M, Drexler W, Levecq X, Lamory B, Ritter M, Prager S, Hafner J, Schmidt-Erfurth U, Pircher M. Multi-modal adaptive optics system including fundus photography and optical coherence tomography for the clinical setting. BIOMEDICAL OPTICS EXPRESS 2016; 7:1783-96. [PMID: 27231621 PMCID: PMC4871081 DOI: 10.1364/boe.7.001783] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/21/2016] [Accepted: 04/01/2016] [Indexed: 05/03/2023]
Abstract
We present a new compact multi-modal imaging prototype that combines an adaptive optics (AO) fundus camera with AO-optical coherence tomography (OCT) in a single instrument. The prototype allows acquiring AO fundus images with a field of view of 4°x4° and with a frame rate of 10fps. The exposure time of a single image is 10 ms. The short exposure time results in nearly motion artifact-free high resolution images of the retina. The AO-OCT mode allows acquiring volumetric data of the retina at 200kHz A-scan rate with a transverse resolution of ~4 µm and an axial resolution of ~5 µm. OCT imaging is acquired within a field of view of 2°x2° located at the central part of the AO fundus image. Recording of OCT volume data takes 0.8 seconds. The performance of the new system is tested in healthy volunteers and patients with retinal diseases.
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Affiliation(s)
- Matthias Salas
- Center of Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Wolfgang Drexler
- Center of Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Xavier Levecq
- Imagine Eyes, 18 Rue Charles de Gaulle 91400 Orsay, France
| | - Barbara Lamory
- Imagine Eyes, 18 Rue Charles de Gaulle 91400 Orsay, France
| | - Markus Ritter
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Sonja Prager
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Julia Hafner
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Ursula Schmidt-Erfurth
- Department of Ophthalmology and Optometry, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
| | - Michael Pircher
- Center of Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20 A-1090 Vienna, Austria
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Huang G, Luo T, Gast TJ, Burns SA, Malinovsky VE, Swanson WH. Imaging Glaucomatous Damage Across the Temporal Raphe. Invest Ophthalmol Vis Sci 2015; 56:3496-504. [PMID: 26047040 DOI: 10.1167/iovs.15-16730] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To image and analyze anatomical differences at the temporal raphe between normal and glaucomatous eyes using adaptive optics scanning laser ophthalmoscopy (AOSLO) and optical coherence tomography (OCT), and to relate these differences to visual field measurements. METHODS Nine glaucomatous eyes of 9 patients (age 54-78 years, mean deviation of visual field [MD] -5.03 to -0.20 dB) and 10 normal eyes of 10 controls (age 54-81, MD -1.13 to +1.39 dB) were enrolled. All the participants were imaged in a region that was centered approximately 9° temporal to the fovea. The size of imaging region was at least 10° vertically by 4° horizontally. The raphe gap, defined as the distance between the superior and inferior retinal nerve fiber layer (RNFL) bundles, was measured. A bundle index was computed to quantify the relative reflectivity and density of the nerve fiber bundles. We also measured thickness of the ganglion cell complex (GCC) and RNFL. RESULTS The raphe gap was larger in glaucomatous eyes than control eyes. Specifically, eight glaucomatous eyes with local averaged field loss no worse than -3.5 dB had larger raphe gaps than all control eyes. The bundle index, GCC thickness, and RNFL thickness were on average reduced in glaucomatous eyes, with the first two showing statistically significant differences between the two groups. CONCLUSIONS Structural changes in the temporal raphe were observed and quantified even when local functional loss was mild. These techniques open the possibility of using the raphe as a site for glaucoma research and clinical assessment.
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18
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Liu C, Kim MK. Digital adaptive optics line-scanning confocal imaging system. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:111203. [PMID: 26140334 PMCID: PMC4572096 DOI: 10.1117/1.jbo.20.11.111203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 06/05/2015] [Indexed: 05/30/2023]
Abstract
A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.
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Affiliation(s)
- Changgeng Liu
- University of South Florida, Department of Physics, Digital Holography and Microscopy Laboratory, Tampa, Florida 33620, United States
| | - Myung K. Kim
- University of South Florida, Department of Physics, Digital Holography and Microscopy Laboratory, Tampa, Florida 33620, United States
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19
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Liu C, Marchesini S, Kim MK. Quantitative phase-contrast confocal microscope. OPTICS EXPRESS 2014; 22:17830-17839. [PMID: 25089404 PMCID: PMC4162347 DOI: 10.1364/oe.22.017830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/06/2014] [Accepted: 07/07/2014] [Indexed: 05/30/2023]
Abstract
We present a quantitative phase-contrast confocal microscope (QPCCM) by combining a line-scanning confocal system with digital holography (DH). This combination can merge the merits of these two different imaging modalities. High-contrast intensity images with low coherent noise, and the optical sectioning capability are made available due to the confocality. Phase profiles of the samples become accessible thanks to DH. QPCCM is able to quantitatively measure the phase variations of optical sections of the opaque samples and has the potential to take high-quality intensity and phase images of non-opaque samples such as many biological samples. Because each line scan is recorded by a hologram that may contain the optical aberrations of the system, it opens avenues for a variety of numerical aberration compensation methods and development of full digital adaptive optics confocal system to emulate current hardware-based adaptive optics system for biomedical imaging, especially ophthalmic imaging. Preliminary experiments with a microscope objective of NA 0.65 and 40 × on opaque samples are presented to demonstrate this idea. The measured lateral and axial resolutions of the intensity images from the current system are ~0.64μm and ~2.70μm respectively. The noise level of the phase profile by QPCCM is ~2.4nm which is better than the result by DH.
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Affiliation(s)
- Changgeng Liu
- Digital Holography and Microscopy Laboratory, Department of Physics, University of South Florida, Tampa, FL 33620,
USA
| | - Stefano Marchesini
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720,
USA
| | - Myung K. Kim
- Digital Holography and Microscopy Laboratory, Department of Physics, University of South Florida, Tampa, FL 33620,
USA
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20
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Chiu SJ, Lokhnygina Y, Dubis AM, Dubra A, Carroll J, Izatt JA, Farsiu S. Automatic cone photoreceptor segmentation using graph theory and dynamic programming. BIOMEDICAL OPTICS EXPRESS 2013; 4:924-37. [PMID: 23761854 PMCID: PMC3675871 DOI: 10.1364/boe.4.000924] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/13/2013] [Accepted: 05/17/2013] [Indexed: 05/18/2023]
Abstract
Geometrical analysis of the photoreceptor mosaic can reveal subclinical ocular pathologies. In this paper, we describe a fully automatic algorithm to identify and segment photoreceptors in adaptive optics ophthalmoscope images of the photoreceptor mosaic. This method is an extension of our previously described closed contour segmentation framework based on graph theory and dynamic programming (GTDP). We validated the performance of the proposed algorithm by comparing it to the state-of-the-art technique on a large data set consisting of over 200,000 cones and posted the results online. We found that the GTDP method achieved a higher detection rate, decreasing the cone miss rate by over a factor of five.
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Affiliation(s)
- Stephanie J. Chiu
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
| | - Yuliya Lokhnygina
- Department of Biostatistics & Bioinformatics, Duke University, Durham, North Carolina 27708, USA
| | - Adam M. Dubis
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Alfredo Dubra
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - Joseph Carroll
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
| | - Joseph A. Izatt
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Sina Farsiu
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina 27710, USA
- Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA
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21
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Glazowski C, Rajadhyaksha M. Optimal detection pinhole for lowering speckle noise while maintaining adequate optical sectioning in confocal reflectance microscopes. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:085001. [PMID: 23224184 PMCID: PMC3412991 DOI: 10.1117/1.jbo.17.8.085001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 07/02/2012] [Accepted: 07/16/2012] [Indexed: 05/21/2023]
Abstract
Coherent speckle influences the resulting image when narrow spectral line-width and single spatial mode illumination are used, though these are the same light-source properties that provide the best radiance-to-cost ratio. However, a suitable size of the detection pinhole can be chosen to maintain adequate optical sectioning while making the probability density of the speckle noise more normal and reducing its effect. The result is a qualitatively better image with improved contrast, which is easier to read. With theoretical statistics and experimental results, we show that the detection pinhole size is a fundamental parameter for designing imaging systems for use in turbid media.
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22
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Yamaguchi T, Mihashi T, Kitaguchi Y, Kanda H, Morimoto T, Fujikado T. Adaptive optics dioptric scanning ophthalmoscope with a wider field of view similar to those of normal ophthalmoscopes. OPTICS LETTERS 2012; 37:2496-2498. [PMID: 22743433 DOI: 10.1364/ol.37.002496] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We introduce a newly developed adaptive optics dioptric scanning ophthalmoscope (AO-DSO) in which all powered optical parts were refractive lenses instead of concave or convex mirrors. By designing dioptric optics, we were able to achieve a compact instrument with a 10 deg field of view (FOV10) and 1.5 deg field of view (FOV1.5) high-resolution imaging. Although the resolution of FOV10 was sacrificed because of the variation of aberrations of the eye over the 10 deg field, our system works with AO in the case of FOV1.5 and can be used as a scanning laser ophthalmoscope with good optical slicing in the case of FOV10. To test the ability of the AO-DSO, we performed imaging on a normal subject and on a patient with occult macular dystrophy.
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Affiliation(s)
- Tatsuo Yamaguchi
- Optics Lab, Topcon Corp., 75-1Hasunumacho, Itabashi, 174-8580, Japan
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23
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Huang H, Inoue T, Tanaka H. Stabilized high-accuracy correction of ocular aberrations with liquid crystal on silicon spatial light modulator in adaptive optics retinal imaging system. OPTICS EXPRESS 2011; 19:15026-15040. [PMID: 21934864 DOI: 10.1364/oe.19.015026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We studied the long-term optical performance of an adaptive optics scanning laser ophthalmoscope that uses a liquid crystal on silicon spatial light modulator to correct ocular aberrations. The system achieved good compensation of aberrations while acquiring images of fine retinal structures, excepting during sudden eye movements. The residual wavefront aberrations collected over several minutes in several situations were statistically analyzed. The mean values of the root-mean-square residual wavefront errors were 23-30 nm, and for around 91-94% of the effective time the errors were below the Marechal criterion for diffraction limited imaging. The ability to axially shift the imaging plane to different retinal depths was also demonstrated.
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Affiliation(s)
- Hongxin Huang
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita-Ku, Hamamatsu-City, Shizuoka 434-8601, Japan.
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Godara P, Dubis AM, Roorda A, Duncan JL, Carroll J. Adaptive optics retinal imaging: emerging clinical applications. Optom Vis Sci 2010; 87:930-41. [PMID: 21057346 PMCID: PMC3017557 DOI: 10.1097/opx.0b013e3181ff9a8b] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The human retina is a uniquely accessible tissue. Tools like scanning laser ophthalmoscopy and spectral domain-optical coherence tomography provide clinicians with remarkably clear pictures of the living retina. Although the anterior optics of the eye permit such non-invasive visualization of the retina and associated pathology, the same optics induce significant aberrations that obviate cellular-resolution imaging in most cases. Adaptive optics (AO) imaging systems use active optical elements to compensate for aberrations in the optical path between the object and the camera. When applied to the human eye, AO allows direct visualization of individual rod and cone photoreceptor cells, retinal pigment epithelium cells, and white blood cells. AO imaging has changed the way vision scientists and ophthalmologists see the retina, helping to clarify our understanding of retinal structure, function, and the etiology of various retinal pathologies. Here, we review some of the advances that were made possible with AO imaging of the human retina and discuss applications and future prospects for clinical imaging.
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Affiliation(s)
- Pooja Godara
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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25
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Yang Q, Arathorn DW, Tiruveedhula P, Vogel CR, Roorda A. Design of an integrated hardware interface for AOSLO image capture and cone-targeted stimulus delivery. OPTICS EXPRESS 2010; 18:17841-58. [PMID: 20721171 PMCID: PMC3408953 DOI: 10.1364/oe.18.017841] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 07/27/2010] [Accepted: 07/28/2010] [Indexed: 05/18/2023]
Abstract
We demonstrate an integrated FPGA solution to project highly stabilized, aberration-corrected stimuli directly onto the retina by means of real-time retinal image motion signals in combination with high speed modulation of a scanning laser. By reducing the latency between target location prediction and stimulus delivery, the stimulus location accuracy, in a subject with good fixation, is improved to 0.15 arcminutes from 0.26 arcminutes in our earlier solution. We also demonstrate the new FPGA solution is capable of delivering stabilized large stimulus pattern (up to 256 x 256 pixels) to the retina.
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Affiliation(s)
- Qiang Yang
- Montana State University, Bozeman, MT 59717, USA.
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26
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Li KY, Tiruveedhula P, Roorda A. Intersubject variability of foveal cone photoreceptor density in relation to eye length. Invest Ophthalmol Vis Sci 2010; 51:6858-67. [PMID: 20688730 DOI: 10.1167/iovs.10-5499] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
PURPOSE Adaptive optics scanning laser ophthalmoscopy (AOSLO) under optimized wavefront correction allows for routine imaging of foveal cone photoreceptors. The intersubject variability of foveal cone density was measured and its relation to eye length evaluated. METHODS AOSLO was used to image 18 healthy eyes with axial lengths from 22.86 to 28.31 mm. Ocular biometry and an eye model were used to estimate the retinal magnification factor. Individual cones in the AOSLO images were labeled, and the locations were used to generate topographic maps representing the spatial distribution of density. Representative retinal (cones/mm(2)) and angular (cones/deg(2)) cone densities at specific eccentricities were calculated from these maps. RESULTS The entire foveal cone mosaic was resolved in four eyes, whereas the cones within 0.03 mm eccentricity remained unresolved in most eyes. The preferred retinal locus deviated significantly (P < 0.001) from the point of peak cone density for all except one individual. A significant decrease in retinal density (P < 0.05) with increasing axial length was observed at 0.30 mm eccentricity but not closer. Longer, more myopic eyes generally had higher angular density near the foveal center than the shorter eyes, but by 1°, this difference was nullified by retinal expansion, and so angular densities across all eyes were similar. CONCLUSIONS The AOSLO can resolve the smallest foveal cones in certain eyes. Although myopia causes retinal stretching in the fovea, its effect within the foveola is confounded by factors other than cone density that have high levels of intersubject variability.
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Affiliation(s)
- Kaccie Y Li
- School of Optometry, University of California, Berkeley, CA 94720-2020, USA
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27
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Abstract
Adaptive optics (AO) describes a set of tools to correct or control aberrations in any optical system. In the eye, AO allows for precise control of the ocular aberrations. If used to correct aberrations over a large pupil, for example, cellular level resolution in retinal images can be achieved. AO systems have been demonstrated for advanced ophthalmoscopy as well as for testing and/or improving vision. In fact, AO can be integrated to any ophthalmic instrument where the optics of the eye is involved, with a scope of applications ranging from phoropters to optical coherence tomography systems. In this article, I discuss the applications and advantages of using AO in a specific system, the AO scanning laser ophthalmoscope. Since the Borish award was, in part, awarded to me because of this effort, I felt it appropriate to select this as the topic for this article. Furthermore, users of AO scanning laser ophthalmoscope continue to appreciate the benefits of the technology, some of which were not anticipated at the time of development, and so it is time to revisit this topic and summarize them in a single article.
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28
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Mujat M, Ferguson RD, Patel AH, Iftimia N, Lue N, Hammer DX. High resolution multimodal clinical ophthalmic imaging system. OPTICS EXPRESS 2010; 18:11607-21. [PMID: 20589021 PMCID: PMC2958093 DOI: 10.1364/oe.18.011607] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 04/29/2010] [Accepted: 05/08/2010] [Indexed: 05/18/2023]
Abstract
We developed a multimodal adaptive optics (AO) retinal imager which is the first to combine high performance AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. Such systems are becoming ever more essential to vision research and are expected to prove their clinical value for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa. The SSOCT channel operates at a wavelength of 1 microm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. This AO system is designed for use in clinical populations; a dual deformable mirror (DM) configuration allows simultaneous low- and high-order aberration correction over a large range of refractions and ocular media quality. The system also includes a wide field (33 deg.) line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation, an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of lateral eye motion, and a high-resolution LCD-based fixation target for presentation of visual cues. The system was tested in human subjects without retinal disease for performance optimization and validation. We were able to resolve and quantify cone photoreceptors across the macula to within approximately 0.5 deg (approximately 100-150 microm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve features deep into the choroid. The prototype presented here is the first of a new class of powerful flexible imaging platforms that will provide clinicians and researchers with high-resolution, high performance adaptive optics imaging to help guide therapies, develop new drugs, and improve patient outcomes.
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Affiliation(s)
- Mircea Mujat
- Physical Sciences Inc., 20 New England Business Center, Andover MA 01810, USA.
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29
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Abstract
Many important eye diseases as well as systemic diseases manifest themselves in the retina. While a number of other anatomical structures contribute to the process of vision, this review focuses on retinal imaging and image analysis. Following a brief overview of the most prevalent causes of blindness in the industrialized world that includes age-related macular degeneration, diabetic retinopathy, and glaucoma, the review is devoted to retinal imaging and image analysis methods and their clinical implications. Methods for 2-D fundus imaging and techniques for 3-D optical coherence tomography (OCT) imaging are reviewed. Special attention is given to quantitative techniques for analysis of fundus photographs with a focus on clinically relevant assessment of retinal vasculature, identification of retinal lesions, assessment of optic nerve head (ONH) shape, building retinal atlases, and to automated methods for population screening for retinal diseases. A separate section is devoted to 3-D analysis of OCT images, describing methods for segmentation and analysis of retinal layers, retinal vasculature, and 2-D/3-D detection of symptomatic exudate-associated derangements, as well as to OCT-based analysis of ONH morphology and shape. Throughout the paper, aspects of image acquisition, image analysis, and clinical relevance are treated together considering their mutually interlinked relationships.
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Affiliation(s)
- Michael D Abràmoff
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA 52242, USA
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30
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Abstract
Many important eye diseases as well as systemic diseases manifest themselves in the retina. While a number of other anatomical structures contribute to the process of vision, this review focuses on retinal imaging and image analysis. Following a brief overview of the most prevalent causes of blindness in the industrialized world that includes age-related macular degeneration, diabetic retinopathy, and glaucoma, the review is devoted to retinal imaging and image analysis methods and their clinical implications. Methods for 2-D fundus imaging and techniques for 3-D optical coherence tomography (OCT) imaging are reviewed. Special attention is given to quantitative techniques for analysis of fundus photographs with a focus on clinically relevant assessment of retinal vasculature, identification of retinal lesions, assessment of optic nerve head (ONH) shape, building retinal atlases, and to automated methods for population screening for retinal diseases. A separate section is devoted to 3-D analysis of OCT images, describing methods for segmentation and analysis of retinal layers, retinal vasculature, and 2-D/3-D detection of symptomatic exudate-associated derangements, as well as to OCT-based analysis of ONH morphology and shape. Throughout the paper, aspects of image acquisition, image analysis, and clinical relevance are treated together considering their mutually interlinked relationships.
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Affiliation(s)
- Michael D Abràmoff
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA 52242, USA
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