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Cabral D, Bijon J, Vaz M, Naguib M, Sarraf D, Freund KB. Clinical Implications of Alternating Hypointense Bands on OCT Angiography in Retinal Vascular Occlusive Disease. Ophthalmol Retina 2024:S2468-6530(24)00225-2. [PMID: 38719189 DOI: 10.1016/j.oret.2024.04.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 04/17/2024] [Accepted: 04/29/2024] [Indexed: 06/13/2024]
Abstract
PURPOSE To demonstrate the relationship between alternating hypointense signal bands on OCT angiography (OCTA), real-time fluorescein angiography (FA), and structural OCT findings in patients with retinal vascular occlusive disease (RVOD). DESIGN Retrospective, consecutive case series. SUBJECTS Consecutive patients with a clinical diagnosis of acute RVOD and alternating bands of hypointense OCTA flow signal on en face projections. METHODS Complete ophthalmic examination and multimodal imaging, including color fundus photography, real-time FA, spectral-domain OCT, and OCTA performed with different instruments having different scan speeds and acquisition protocols. MAIN OUTCOME MEASURES The primary outcomes were: hypointense OCTA band characteristics (number, width, orientation, and location), OCTA acquisition characteristics (speed and scan direction), and FA findings including delayed arteriovenous (AV) transit and pulsatile flow. Secondary outcomes were: structural OCT changes including retinal fluid, paracentral acute middle maculopathy (PAMM) lesion, and a prominent middle limiting membrane (p-MLM) sign. RESULTS OCT angiography hypointense bands were detected in the superficial and deep vascular plexuses in 9 eyes of 9 patients with either partial central retinal vein occlusion (RVO) or nonischemic RVO. When obtained on the same device, hypointense bands were thinner and more numerous at lower (100 kHz) scan speeds compared with higher (200 kHz) scan speeds. Band orientation was parallel to the OCTA scan direction, and their extent correlated with the area of delayed AV transit on FA. Structural OCT showed multiple PAMM lesions in 78% of cases and a p-MLM sign centered in the fovea in 44% of cases. CONCLUSIONS OCT hypointense bands are a novel biomarker in RVOD indicating delayed AV transit and pulsatile filling without the need for dye angiography. Structural OCT often shows PAMM in these eyes and, less commonly, a p-MLM sign. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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Affiliation(s)
- Diogo Cabral
- Unidade Local de Saúde Almada-Seixal, Almada, Portugal; NMS Research, NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Jacques Bijon
- Vitreous Retina Macula Consultants of New York, New York, New York
| | - Mariana Vaz
- Unidade Local de Saúde Almada-Seixal, Almada, Portugal
| | - Mina Naguib
- Vitreous Retina Macula Consultants of New York, New York, New York
| | - David Sarraf
- Retinal Disorders and Ophthalmic Genetics Division, Stein Eye Institute, University of California, Los Angeles, Los Angeles, California
| | - K Bailey Freund
- Vitreous Retina Macula Consultants of New York, New York, New York; Department of Ophthalmology, NYU Grossman School of Medicine, New York, New York.
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2
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Untracht GR, Durkee MS, Zhao M, Kwok-Cheung Lam A, Sikorski BL, Sarunic MV, Andersen PE, Sampson DD, Chen FK, Sampson DM. Towards standardising retinal OCT angiography image analysis with open-source toolbox OCTAVA. Sci Rep 2024; 14:5979. [PMID: 38472220 PMCID: PMC10933365 DOI: 10.1038/s41598-024-53501-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 02/01/2024] [Indexed: 03/14/2024] Open
Abstract
Quantitative assessment of retinal microvasculature in optical coherence tomography angiography (OCTA) images is important for studying, diagnosing, monitoring, and guiding the treatment of ocular and systemic diseases. However, the OCTA user community lacks universal and transparent image analysis tools that can be applied to images from a range of OCTA instruments and provide reliable and consistent microvascular metrics from diverse datasets. We present a retinal extension to the OCTA Vascular Analyser (OCTAVA) that addresses the challenges of providing robust, easy-to-use, and transparent analysis of retinal OCTA images. OCTAVA is a user-friendly, open-source toolbox that can analyse retinal OCTA images from various instruments. The toolbox delivers seven microvascular metrics for the whole image or subregions and six metrics characterising the foveal avascular zone. We validate OCTAVA using images collected by four commercial OCTA instruments demonstrating robust performance across datasets from different instruments acquired at different sites from different study cohorts. We show that OCTAVA delivers values for retinal microvascular metrics comparable to the literature and reduces their variation between studies compared to their commercial equivalents. By making OCTAVA publicly available, we aim to expand standardised research and thereby improve the reproducibility of quantitative analysis of retinal microvascular imaging. Such improvements will help to better identify more reliable and sensitive biomarkers of ocular and systemic diseases.
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Affiliation(s)
- Gavrielle R Untracht
- Department of Health Technology, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
- School of Biosciences, The University of Surrey, Guildford, GU27XH, UK
| | | | - Mei Zhao
- Centre for Myopia Research, School of Optometry, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Andrew Kwok-Cheung Lam
- Centre for Myopia Research, School of Optometry, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Bartosz L Sikorski
- Department of Ophthalmology, Nicolaus Copernicus University, 85-090, Bydgoszcz, Poland
- International Center for Translational Eye Research (ICTER), Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland
| | - Marinko V Sarunic
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E6BT, UK
- Institute of Ophthalmology, University College London, London, EC1V2PD, UK
| | - Peter E Andersen
- Department of Health Technology, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - David D Sampson
- School of Computer Science and Electronic Engineering, The University of Surrey, Guildford, GU27XH, UK
| | - Fred K Chen
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Perth, WA, 6009, Australia
- Department of Ophthalmology, Royal Perth Hospital, Perth, WA, 6000, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, VIC, 3002, Australia
| | - Danuta M Sampson
- School of Biosciences, The University of Surrey, Guildford, GU27XH, UK.
- Institute of Ophthalmology, University College London, London, EC1V2PD, UK.
- Centre for Ophthalmology and Visual Science (Incorporating Lions Eye Institute), The University of Western Australia, Perth, WA, 6009, Australia.
- Department of Optometry, School of Allied Health, The University of Western Australia, Perth, WA, 6009, Australia.
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3
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Hong J, Tan SS, Chua J. Optical coherence tomography angiography in glaucoma. Clin Exp Optom 2024; 107:110-121. [PMID: 38266148 DOI: 10.1080/08164622.2024.2306963] [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: 10/24/2023] [Accepted: 01/11/2024] [Indexed: 01/26/2024] Open
Abstract
The use of optical coherence tomography angiography (OCTA) holds significant promise for optometrists in the diagnosis and management of glaucoma. It offers reliable differentiation of glaucomatous eyes from healthy ones and extends monitoring capabilities for advanced cases. OCTA represents a valuable addition to traditional assessment methods, particularly in complex cases. Glaucoma, a major cause of irreversible blindness, is traditionally diagnosed using structural and functional metrics. With growing interest, OCTA is being explored to diagnose, monitor, and manage glaucoma. This review focuses on the application of OCTA in glaucoma patients. A database search was carried out using Embase Elsevier (n = 664), PubMed (n = 574), and Cochrane Central Register of Controlled Trials (n = 19) on 15 August 2023. After deduplication and screening, 272 original papers were included in the narrative review. Inclusion criteria comprised English-language original studies on OCTA use in human glaucoma patients, with or without healthy controls. Exclusion criteria encompassed animal studies, in-vivo/in-vitro research, reviews, and congress abstracts. OCTA has good repeatability and reproducibility. OCTA metrics have good discriminatory power to differentiate glaucomatous eyes from healthy eyes and show strong associations with structural changes and visual field defects. OCTA can extend the monitoring of advanced glaucoma, addressing the 'floor effect' of traditional structural measurements. OCTA metrics can be affected by the choice of OCTA machine, post-image processing algorithms, systemic diseases, and ocular factors. Image artefacts can affect the accuracy of OCTA measurements, and proper scan quality evaluation is crucial to ensure reliable results. Additionally, artificial intelligence techniques offer promise for enhancing the diagnostic accuracy of OCTA by combining data from various retinal layers and regions. OCTA complements traditional methods in assessing glaucoma, especially in challenging cases, providing valuable insights for detection and management. Further research and clinical validation are needed to integrate OCTA into routine practice.
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Affiliation(s)
- Jimmy Hong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
| | - Shayne S Tan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
| | - Jacqueline Chua
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
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Schneider S, Kallab M, Murauer O, Reisinger AS, Strohmaier S, Huang AS, Bolz M, Strohmaier CA. Bleb vessel density as a predictive factor for surgical revisions after Preserflo Microshunt implantation. Acta Ophthalmol 2024. [PMID: 38306110 DOI: 10.1111/aos.16642] [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: 08/16/2023] [Revised: 12/20/2023] [Accepted: 01/15/2024] [Indexed: 02/03/2024]
Abstract
PURPOSE Bleb failure is a common complication after glaucoma filtration surgery. Different bleb classification schemes incorporating filtration bleb vascularization have been proposed, but the reported correlation with intraocular pressure (IOP) has been variable, possibly because of subjective vascularization grading. The purpose of the present study was to evaluate bleb vascularization after Preserflo Microshunt (PM) implantation using anterior segment OCT-angiography (AS-OCTA) as a biomarker for bleb failure. METHODS Twenty-three eyes of twenty-three patients underwent PM implantation. Up to 12 months after surgery PM scleral passage-centred AS-OCTA measurements (PLEX Elite 9000) for bleb-vessel density (BVD) determination were performed and IOP as well as necessity for surgical revisions (needling and open revision) were documented. After multi-step image analysis (region of interest definition, artefact removal, binarization, BVD calculation), the predictive value of early postoperative BVD for surgical revisions was assessed using logistic regression modelling. RESULTS Baseline IOP (23.57 ± 7.75 mmHg) decreased significantly to 8.30 ± 2.12, 9.17 ± 2.33 and 11.70 ± 4.40 mmHg after 1, 2 and 4 week(s), and 13.48 ± 5.83, 11.87 ± 4.49, 12.30 ± 6.65, 11.87 ± 3.11 and 13.05 ± 4.12 mmHg after 2, 3, 6, 9 and 12 month(s), respectively (p < 0.001). Nine patients (39%) needed surgical revisions after a median time of 2 months. Bleb vessel densities at 2 and 4 weeks were significantly associated with future surgical revisions upon logistic regression analysis (2 W/4 W likelihood-ratio test p-value: 0.0244/0.0098; 2 W/4 W area under the receiver operating characteristics curve: 0.796/0.909). CONCLUSION Filtration bleb vessel density can be determined using AS-OCTA in the early postoperative period and is predictive for bleb failure after PM implantation.
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Affiliation(s)
- Sophie Schneider
- Department of Ophthalmology and Optometry, Kepler University Hospital, Johannes Kepler University, Linz, Austria
| | - Martin Kallab
- Department of Ophthalmology and Optometry, Kepler University Hospital, Johannes Kepler University, Linz, Austria
| | - Olivia Murauer
- Department of Ophthalmology and Optometry, Kepler University Hospital, Johannes Kepler University, Linz, Austria
| | - Anna-Sophie Reisinger
- Department of Ophthalmology and Optometry, Kepler University Hospital, Johannes Kepler University, Linz, Austria
| | - Susanne Strohmaier
- Department of Epidemiology, Center for Public Health, Medical University of Vienna, Vienna, Austria
| | - Alex S Huang
- Hamilton Glaucoma Center, The Viterbi Family Department of Ophthalmology, Shiley Eye Institute, University of California, San Diego, California, USA
| | - Matthias Bolz
- Department of Ophthalmology and Optometry, Kepler University Hospital, Johannes Kepler University, Linz, Austria
| | - Clemens A Strohmaier
- Department of Ophthalmology and Optometry, Kepler University Hospital, Johannes Kepler University, Linz, Austria
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Schmetterer L, Scholl H, Garhöfer G, Janeschitz-Kriegl L, Corvi F, Sadda SR, Medeiros FA. Endpoints for clinical trials in ophthalmology. Prog Retin Eye Res 2023; 97:101160. [PMID: 36599784 DOI: 10.1016/j.preteyeres.2022.101160] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 12/22/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023]
Abstract
With the identification of novel targets, the number of interventional clinical trials in ophthalmology has increased. Visual acuity has for a long time been considered the gold standard endpoint for clinical trials, but in the recent years it became evident that other endpoints are required for many indications including geographic atrophy and inherited retinal disease. In glaucoma the currently available drugs were approved based on their IOP lowering capacity. Some recent findings do, however, indicate that at the same level of IOP reduction, not all drugs have the same effect on visual field progression. For neuroprotection trials in glaucoma, novel surrogate endpoints are required, which may either include functional or structural parameters or a combination of both. A number of potential surrogate endpoints for ophthalmology clinical trials have been identified, but their validation is complicated and requires solid scientific evidence. In this article we summarize candidates for clinical endpoints in ophthalmology with a focus on retinal disease and glaucoma. Functional and structural biomarkers, as well as quality of life measures are discussed, and their potential to serve as endpoints in pivotal trials is critically evaluated.
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Affiliation(s)
- Leopold Schmetterer
- Singapore Eye Research Institute, Singapore; SERI-NTU Advanced Ocular Engineering (STANCE), Singapore; Academic Clinical Program, Duke-NUS Medical School, Singapore; School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore; Department of Clinical Pharmacology, Medical University Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria; Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland.
| | - Hendrik Scholl
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland; Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University Vienna, Vienna, Austria
| | - Lucas Janeschitz-Kriegl
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland; Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Federico Corvi
- Eye Clinic, Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan, Italy
| | - SriniVas R Sadda
- Doheny Eye Institute, Los Angeles, CA, USA; Department of Ophthalmology, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Felipe A Medeiros
- Vision, Imaging and Performance Laboratory, Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
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6
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Lazăr AS, Stanca HT, Tăbăcaru B, Danielescu C, Munteanu M, Stanca S. Quantitative Parameters Relevant for Diabetic Macular Edema Evaluation by Optical Coherence Tomography Angiography. MEDICINA (KAUNAS, LITHUANIA) 2023; 59:1120. [PMID: 37374324 DOI: 10.3390/medicina59061120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/06/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023]
Abstract
Diabetic macular edema (DME) is one of the main ocular complications of diabetes mellitus (DM) that can lead to important vision loss in diabetic patients. In clinical practice, there are cases of DME with unsatisfying treatment responses, despite adequate therapeutic management. Diabetic macular ischemia (DMI) is one of the causes suggested to be associated with the persistence of fluid accumulation. Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality, able to give in-depth information about retinal vascularization in a 3-dimensional manner. The OCTA devices currently available can provide various OCTA metrics that quantitatively assess the retinal microvasculature. In this paper, we reviewed the results of multiple studies that investigated the changes in OCTA metrics in the setting of DME and their possible contribution to the diagnosis, therapeutic management, follow-up and prognosis of patients with DME. We analyzed and compared relevant studies that investigated OCTA parameters related to changes in macular perfusion in the setting of DME and we evaluated the correlations between DME and several quantitative parameters, such as vessel density (VD), perfusion density (PD), foveal avascular zone (FAZ)-related parameters, as well as complexity indices of retinal vasculature. The results of our research showed that OCTA metrics, evaluated especially at the level of the deep vascular plexus (DVP), are useful instruments that can contribute to the assessment of patients with DME.
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Affiliation(s)
- Alina-Simona Lazăr
- Doctoral School, "Carol Davila" University of Medicine and Pharmacy, Strada Dionisie Lupu No. 37, 020021 Bucharest, Romania
- Clinical Department of Ophthalmology, "Prof. Dr. Agrippa Ionescu" Emergency Hospital, Strada Ion Mincu No. 7, 011356 Bucharest, Romania
| | - Horia T Stanca
- Doctoral School, "Carol Davila" University of Medicine and Pharmacy, Strada Dionisie Lupu No. 37, 020021 Bucharest, Romania
- Clinical Department of Ophthalmology, "Prof. Dr. Agrippa Ionescu" Emergency Hospital, Strada Ion Mincu No. 7, 011356 Bucharest, Romania
| | - Bogdana Tăbăcaru
- Clinical Department of Ophthalmology, "Prof. Dr. Agrippa Ionescu" Emergency Hospital, Strada Ion Mincu No. 7, 011356 Bucharest, Romania
| | - Ciprian Danielescu
- Department of Ophthalmology, Faculty of Medicine, University of Medicine and Pharmacy "Grigore T. Popa", Strada Universitatii No. 16, 700115 Iasi, Romania
| | - Mihnea Munteanu
- Department of Ophthalmology, "Victor Babes" University of Medicine and Pharmacy, 300041 Timisoara, Romania
| | - Simona Stanca
- Clinical Department of Pediatrics, University of Medicine and Pharmacy "Carol Davila", Strada Dionisie Lupu No. 37, 020021 Bucharest, Romania
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Han L, Tan B, Schmetterer L, Bizheva K. Localized transverse flow measurement with dynamic light scattering line-scan OCT. BIOMEDICAL OPTICS EXPRESS 2023; 14:883-905. [PMID: 36874477 PMCID: PMC9979667 DOI: 10.1364/boe.484257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 01/06/2023] [Indexed: 06/18/2023]
Abstract
A novel decorrelation-based approach for measuring localized transverse flow velocity using line-scan (LS) optical coherence tomography (OCT) is proposed. The new approach allows for separation of the flow velocity component along the line-illumination direction of the imaging beam from other orthogonal velocity components, from particle diffusion motion, and from noise-induced distortion in the OCT signal's temporal autocorrelation. The new method was verified by imaging flow in a glass capillary and a microfluidic device and mapping the spatial distribution of the flow velocity within the beam's illumination plane. This method can be extended in the future to map the three-dimensional flow velocity fields for both ex-vivo and in-vivo applications.
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Affiliation(s)
- Le Han
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Bingyao Tan
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 639798, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE), 639798, Singapore
- Singapore Eye Research Institute, Singapore National Eye Center, 169856, Singapore
| | - Leopold Schmetterer
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 639798, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE), 639798, Singapore
- Singapore Eye Research Institute, Singapore National Eye Center, 169856, Singapore
- Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
- Department of Clinical Pharmacology, Medical University Vienna, Vienna, Austria
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria
| | - Kostadinka Bizheva
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Dept. of Systems Design Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- School of Optometry and Vision Sciences, Univ. of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Arrigo A, Aragona E, Battaglia Parodi M, Bandello F. Quantitative approaches in multimodal fundus imaging: State of the art and future perspectives. Prog Retin Eye Res 2023; 92:101111. [PMID: 35933313 DOI: 10.1016/j.preteyeres.2022.101111] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/16/2022] [Accepted: 07/19/2022] [Indexed: 02/01/2023]
Abstract
When it first appeared, multimodal fundus imaging revolutionized the diagnostic workup and provided extremely useful new insights into the pathogenesis of fundus diseases. The recent addition of quantitative approaches has further expanded the amount of information that can be obtained. In spite of the growing interest in advanced quantitative metrics, the scientific community has not reached a stable consensus on repeatable, standardized quantitative techniques to process and analyze the images. Furthermore, imaging artifacts may considerably affect the processing and interpretation of quantitative data, potentially affecting their reliability. The aim of this survey is to provide a comprehensive summary of the main multimodal imaging techniques, covering their limitations as well as their strengths. We also offer a thorough analysis of current quantitative imaging metrics, looking into their technical features, limitations, and interpretation. In addition, we describe the main imaging artifacts and their potential impact on imaging quality and reliability. The prospect of increasing reliance on artificial intelligence-based analyses suggests there is a need to develop more sophisticated quantitative metrics and to improve imaging technologies, incorporating clear, standardized, post-processing procedures. These measures are becoming urgent if these analyses are to cross the threshold from a research context to real-life clinical practice.
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Affiliation(s)
- Alessandro Arrigo
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy.
| | - Emanuela Aragona
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
| | - Maurizio Battaglia Parodi
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
| | - Francesco Bandello
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, via Olgettina 60, 20132, Milan, Italy
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9
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Microvascular changes in the macular and parafoveal areas of multiple sclerosis patients without optic neuritis. Sci Rep 2022; 12:13366. [PMID: 35922463 PMCID: PMC9349324 DOI: 10.1038/s41598-022-17344-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 07/25/2022] [Indexed: 02/08/2023] Open
Abstract
Retinal imaging has been proposed as a biomarker for neurological diseases such as multiple sclerosis (MS). Recently, a technique for non-invasive assessment of the retinal microvasculature called optical coherence tomography angiography (OCTA) was introduced. We investigated retinal microvasculature alterations in participants with relapsing–remitting MS (RRMS) without history of optic neuritis (ON) and compared them to a healthy control group. The study was performed in a prospective, case–control design, including 58 participants (n = 100 eyes) with RRMS without ON and 78 age- and sex-matched control participants (n = 136 eyes). OCTA images of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris (CC) were obtained using a commercial OCTA system (Zeiss Cirrus HD-5000 Spectral-Domain OCT with AngioPlex OCTA, Carl Zeiss Meditec, Dublin, CA). The outcome variables were perfusion density (PD) and foveal avascular zone (FAZ) features (area and circularity) in both the SCP and DCP, and flow deficit in the CC. MS group had on average higher intraocular pressure (IOP) than controls (P < 0.001). After adjusting for confounders, MS participants showed significantly increased PD in SCP (P = 0.003) and decreased PD in DCP (P < 0.001) as compared to controls. A significant difference was still noted when large vessels (LV) in the SCP were removed from the PD calculation (P = 0.004). Deep FAZ was significantly larger (P = 0.005) and less circular (P < 0.001) in the eyes of MS participants compared to the control ones. Neither LV, PD or FAZ features in the SCP, nor flow deficits in the CC showed any statistically significant differences between the MS group and control group (P > 0.186). Our study indicates that there are microvascular changes in the macular parafoveal retina of RRMS patients without ON, showing increased PD in SCP and decreased PD in DCP. Further studies with a larger cohort of MS patients and MRI correlations are necessary to validate retinal microvascular changes as imaging biomarkers for diagnosis and screening of MS.
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10
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Alexopoulos P, Madu C, Wollstein G, Schuman JS. The Development and Clinical Application of Innovative Optical Ophthalmic Imaging Techniques. Front Med (Lausanne) 2022; 9:891369. [PMID: 35847772 PMCID: PMC9279625 DOI: 10.3389/fmed.2022.891369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/23/2022] [Indexed: 11/22/2022] Open
Abstract
The field of ophthalmic imaging has grown substantially over the last years. Massive improvements in image processing and computer hardware have allowed the emergence of multiple imaging techniques of the eye that can transform patient care. The purpose of this review is to describe the most recent advances in eye imaging and explain how new technologies and imaging methods can be utilized in a clinical setting. The introduction of optical coherence tomography (OCT) was a revolution in eye imaging and has since become the standard of care for a plethora of conditions. Its most recent iterations, OCT angiography, and visible light OCT, as well as imaging modalities, such as fluorescent lifetime imaging ophthalmoscopy, would allow a more thorough evaluation of patients and provide additional information on disease processes. Toward that goal, the application of adaptive optics (AO) and full-field scanning to a variety of eye imaging techniques has further allowed the histologic study of single cells in the retina and anterior segment. Toward the goal of remote eye care and more accessible eye imaging, methods such as handheld OCT devices and imaging through smartphones, have emerged. Finally, incorporating artificial intelligence (AI) in eye images has the potential to become a new milestone for eye imaging while also contributing in social aspects of eye care.
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Affiliation(s)
- Palaiologos Alexopoulos
- Department of Ophthalmology, NYU Langone Health, NYU Grossman School of Medicine, New York, NY, United States
| | - Chisom Madu
- Department of Ophthalmology, NYU Langone Health, NYU Grossman School of Medicine, New York, NY, United States
| | - Gadi Wollstein
- Department of Ophthalmology, NYU Langone Health, NYU Grossman School of Medicine, New York, NY, United States
- Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY, United States
- Center for Neural Science, College of Arts & Science, New York University, New York, NY, United States
| | - Joel S. Schuman
- Department of Ophthalmology, NYU Langone Health, NYU Grossman School of Medicine, New York, NY, United States
- Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY, United States
- Center for Neural Science, College of Arts & Science, New York University, New York, NY, United States
- Department of Electrical and Computer Engineering, NYU Tandon School of Engineering, Brooklyn, NY, United States
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11
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Sampson DM, Dubis AM, Chen FK, Zawadzki RJ, Sampson DD. Towards standardizing retinal optical coherence tomography angiography: a review. LIGHT, SCIENCE & APPLICATIONS 2022; 11:63. [PMID: 35304441 PMCID: PMC8933532 DOI: 10.1038/s41377-022-00740-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 02/01/2022] [Accepted: 02/14/2022] [Indexed: 05/11/2023]
Abstract
The visualization and assessment of retinal microvasculature are important in the study, diagnosis, monitoring, and guidance of treatment of ocular and systemic diseases. With the introduction of optical coherence tomography angiography (OCTA), it has become possible to visualize the retinal microvasculature volumetrically and without a contrast agent. Many lab-based and commercial clinical instruments, imaging protocols and data analysis methods and metrics, have been applied, often inconsistently, resulting in a confusing picture that represents a major barrier to progress in applying OCTA to reduce the burden of disease. Open data and software sharing, and cross-comparison and pooling of data from different studies are rare. These inabilities have impeded building the large databases of annotated OCTA images of healthy and diseased retinas that are necessary to study and define characteristics of specific conditions. This paper addresses the steps needed to standardize OCTA imaging of the human retina to address these limitations. Through review of the OCTA literature, we identify issues and inconsistencies and propose minimum standards for imaging protocols, data analysis methods, metrics, reporting of findings, and clinical practice and, where this is not possible, we identify areas that require further investigation. We hope that this paper will encourage the unification of imaging protocols in OCTA, promote transparency in the process of data collection, analysis, and reporting, and facilitate increasing the impact of OCTA on retinal healthcare delivery and life science investigations.
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Affiliation(s)
- Danuta M Sampson
- Surrey Biophotonics, Centre for Vision, Speech and Signal Processing and School of Biosciences and Medicine, The University of Surrey, Guildford, GU2 7XH, UK.
| | - Adam M Dubis
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Trust and UCL Institute of Ophthalmology, London, EC1V 2PD, UK
| | - Fred K Chen
- Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Nedlands, Western Australia, 6009, Australia
- Department of Ophthalmology, Royal Perth Hospital, Perth, Western Australia, 6000, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, Melbourne, Victoria, 3002, Australia
| | - Robert J Zawadzki
- Department of Ophthalmology & Vision Science, University of California Davis, Sacramento, CA, 95817, USA
| | - David D Sampson
- Surrey Biophotonics, Advanced Technology Institute, School of Physics and School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH, UK
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12
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Chua J, Le T, Sim YC, Chye HY, Tan B, Yao X, Wong D, Ang BWY, Toh D, Lim H, Bryant JA, Wong TY, Chin CWL, Schmetterer L. Relationship of Quantitative Retinal Capillary Network and Myocardial Remodeling in Systemic Hypertension. J Am Heart Assoc 2022; 11:e024226. [PMID: 35253475 PMCID: PMC9075291 DOI: 10.1161/jaha.121.024226] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Background
This study examined the associations between quantitative optical coherence tomography angiography (OCTA) parameters and myocardial abnormalities as documented on cardiovascular magnetic resonance imaging in patients with systemic hypertension.
Methods and Results
We conducted a cross‐sectional study of 118 adults with hypertension (197 eyes). Patients underwent cardiovascular magnetic resonance imaging and OCTA (PLEX Elite 9000, Carl Zeiss Meditec). Associations between OCTA parameters (superficial and deep retinal capillary density) and adverse cardiac remodeling (left ventricular mass, remodeling index, interstitial fibrosis, global longitudinal strain, and presence of left ventricular hypertrophy) were studied using multivariable linear regression analysis with generalized estimating equations. Of the 118 patients with hypertension enrolled (65% men; median [interquartile range] age, 59 [13] years), 29% had left ventricular hypertrophy. After adjusting for age, sex, systolic blood pressure, diabetes, and signal strength of OCTA scans, patients with lower superficial capillary density had significantly higher left ventricular mass (β=−0.150; 95% CI, −0.290 to −0.010), higher interstitial volume (β=−0.270; 95% CI, −0.535 to −0.0015), and worse global longitudinal strain (β=−0.109; 95% CI, −0.187 to −0.032). Lower superficial capillary density was found in patients with hypertension with replacement fibrosis versus no replacement fibrosis (16.53±0.64 mm
‐1
versus 16.96±0.64 mm
‐1
;
P
=0.003).
Conclusions
We showed significant correlations between retinal capillary density and adverse cardiac remodeling markers in patients with hypertension, supporting the notion that the OCTA could provide a non‐invasive index of microcirculation alteration for vascular risk stratification in people with hypertension.
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Affiliation(s)
- Jacqueline Chua
- Singapore Eye Research InstituteSingapore National Eye Centre Singapore Singapore
- Academic Clinical Program Duke‐NUS Medical School National University of Singapore Singapore Singapore
- SERI‐NTU Advanced Ocular Engineering (STANCE) Singapore Singapore
| | - Thu‐Thao Le
- Academic Clinical Program Duke‐NUS Medical School National University of Singapore Singapore Singapore
- National Heart Research Institute SingaporeNational Heart Centre Singapore Singapore Singapore
| | - Yin Ci Sim
- Singapore Eye Research InstituteSingapore National Eye Centre Singapore Singapore
| | - Hui Yi Chye
- Singapore Eye Research InstituteSingapore National Eye Centre Singapore Singapore
| | - Bingyao Tan
- Singapore Eye Research InstituteSingapore National Eye Centre Singapore Singapore
- SERI‐NTU Advanced Ocular Engineering (STANCE) Singapore Singapore
- School of Chemical and Biomedical Engineering Nanyang Technological University Singapore
| | - Xinwen Yao
- Singapore Eye Research InstituteSingapore National Eye Centre Singapore Singapore
- SERI‐NTU Advanced Ocular Engineering (STANCE) Singapore Singapore
- School of Chemical and Biomedical Engineering Nanyang Technological University Singapore
| | - Damon Wong
- Singapore Eye Research InstituteSingapore National Eye Centre Singapore Singapore
- SERI‐NTU Advanced Ocular Engineering (STANCE) Singapore Singapore
- School of Chemical and Biomedical Engineering Nanyang Technological University Singapore
| | - Briana W. Y. Ang
- National Heart Research Institute SingaporeNational Heart Centre Singapore Singapore Singapore
| | - Desiree‐Faye Toh
- National Heart Research Institute SingaporeNational Heart Centre Singapore Singapore Singapore
| | - Huishan Lim
- National Heart Research Institute SingaporeNational Heart Centre Singapore Singapore Singapore
| | - Jennifer A. Bryant
- National Heart Research Institute SingaporeNational Heart Centre Singapore Singapore Singapore
| | - Tien Yin Wong
- Singapore Eye Research InstituteSingapore National Eye Centre Singapore Singapore
- Academic Clinical Program Duke‐NUS Medical School National University of Singapore Singapore Singapore
| | - Calvin Woon Loong Chin
- Academic Clinical Program Duke‐NUS Medical School National University of Singapore Singapore Singapore
- National Heart Research Institute SingaporeNational Heart Centre Singapore Singapore Singapore
| | - Leopold Schmetterer
- Singapore Eye Research InstituteSingapore National Eye Centre Singapore Singapore
- Academic Clinical Program Duke‐NUS Medical School National University of Singapore Singapore Singapore
- SERI‐NTU Advanced Ocular Engineering (STANCE) Singapore Singapore
- School of Chemical and Biomedical Engineering Nanyang Technological University Singapore
- Department of Clinical Pharmacology Medical University Vienna Vienna Austria
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13
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Tan B, Lim NA, Tan R, Gan ATL, Chua J, Nusinovici S, Cheung CMG, Chakravarthy U, Wong TY, Schmetterer L, Tan G. Combining retinal and choroidal microvascular metrics improves discriminative power for diabetic retinopathy. Br J Ophthalmol 2022:bjophthalmol-2021-319739. [PMID: 35140059 PMCID: PMC10359699 DOI: 10.1136/bjophthalmol-2021-319739] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 01/13/2022] [Indexed: 01/04/2023]
Abstract
PURPOSE To use optical coherence tomography angiography (OCTA) parameters from both the retinal and choroidal microvasculature to detect the presence and severity of diabetic retinopathy (DR). METHOD This is a cross-sectional case-control study. OCTA parameters from retinal vasculature, fovea avascular zone (FAZ) and choriocapillaris were evaluated from 3×3 mm2 fovea-centred scans. Areas under the receiver operating characteristic (ROC) curve were used to compare the discriminative power on the presence of diabetes mellitus (DM), the presence of DR and need for referral: group 1 (no DM vs DM no DR), group 2 (no DR vs any DR) and group 3 (non-proliferative DR (NPDR) vs proliferative DR (PDR)). RESULTS 35 eyes from 27 participants with no DM and 132 eyes from 75 with DM were included. DR severity was classified into three groups: no DR group (62 eyes), NPDR (51 eyes), PDR (19 eyes). All retinal vascular parameters, FAZ parameters and choriocapillaris parameters were strongly altered with DR stages (p<0.01), except for the deep plexus FAZ area (p=0.619). Choriocapillaris parameters allowed to better discriminate between no DM versus DM no DR group compared with retinal parameters (areas under the ROC curve=0.954 vs 0.821, p=0.006). A classification model including retinal and choroidal microvasculature significantly improved the discrimination between DR and no DR compared with each parameter separately (p=0.029). CONCLUSIONS Evaluating OCTA parameters from both the retinal and choroidal microvasculature in 3×3 mm scans improves the discrimination of DM and early DR.
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Affiliation(s)
- Bingyao Tan
- Singapore Eye Research Institute, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
| | - Nicole-Ann Lim
- Singapore Eye Research Institute, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, Singapore
| | - Rose Tan
- Singapore Eye Research Institute, Singapore.,Singapore National Eye Centre, Singapore
| | | | - Jacqueline Chua
- Singapore Eye Research Institute, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore.,Singapore National Eye Centre, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore
| | - Simon Nusinovici
- Singapore Eye Research Institute, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore
| | - Chui Ming Gemmy Cheung
- Singapore Eye Research Institute, Singapore.,Singapore National Eye Centre, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore
| | - Usha Chakravarthy
- School of Medicine, Dentistry and Biomedical Sciencens, Queen's University Belfast, Belfast, UK
| | - Tien Yin Wong
- Singapore Eye Research Institute, Singapore.,Singapore National Eye Centre, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore
| | - Leopold Schmetterer
- Singapore Eye Research Institute, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE) Program, Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore.,Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Gavin Tan
- Singapore Eye Research Institute, Singapore .,Singapore National Eye Centre, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore
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14
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Untracht GR, Matos RS, Dikaios N, Bapir M, Durrani AK, Butsabong T, Campagnolo P, Sampson DD, Heiss C, Sampson DM. OCTAVA: An open-source toolbox for quantitative analysis of optical coherence tomography angiography images. PLoS One 2021; 16:e0261052. [PMID: 34882760 PMCID: PMC8659314 DOI: 10.1371/journal.pone.0261052] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 11/24/2021] [Indexed: 12/15/2022] Open
Abstract
Optical coherence tomography angiography (OCTA) performs non-invasive visualization and characterization of microvasculature in research and clinical applications mainly in ophthalmology and dermatology. A wide variety of instruments, imaging protocols, processing methods and metrics have been used to describe the microvasculature, such that comparing different study outcomes is currently not feasible. With the goal of contributing to standardization of OCTA data analysis, we report a user-friendly, open-source toolbox, OCTAVA (OCTA Vascular Analyzer), to automate the pre-processing, segmentation, and quantitative analysis of en face OCTA maximum intensity projection images in a standardized workflow. We present each analysis step, including optimization of filtering and choice of segmentation algorithm, and definition of metrics. We perform quantitative analysis of OCTA images from different commercial and non-commercial instruments and samples and show OCTAVA can accurately and reproducibly determine metrics for characterization of microvasculature. Wide adoption could enable studies and aggregation of data on a scale sufficient to develop reliable microvascular biomarkers for early detection, and to guide treatment, of microvascular disease.
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Affiliation(s)
- Gavrielle R. Untracht
- Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth, Western Australia, Australia
- Surrey Biophotonics, Advanced Technology Institute, School of Physics and School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
- * E-mail:
| | - Rolando S. Matos
- Department of Biochemical Sciences and Department of Clinical and Experimental Medicine, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
| | | | - Mariam Bapir
- Department of Biochemical Sciences and Department of Clinical and Experimental Medicine, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
| | - Abdullah K. Durrani
- Surrey Biophotonics, Advanced Technology Institute, School of Physics and School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
| | - Teemapron Butsabong
- Department of Biochemical Sciences and Department of Clinical and Experimental Medicine, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
| | - Paola Campagnolo
- Department of Biochemical Sciences and Department of Clinical and Experimental Medicine, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
| | - David D. Sampson
- Surrey Biophotonics, Advanced Technology Institute, School of Physics and School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
| | - Christian Heiss
- Department of Biochemical Sciences and Department of Clinical and Experimental Medicine, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
- Surrey and Sussex Healthcare NHS Trust, East Surrey Hospital, Redhill, Surrey, United Kingdom
| | - Danuta M. Sampson
- Department of Biochemical Sciences and Department of Clinical and Experimental Medicine, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, United Kingdom
- Surrey Biophotonics, Centre for Vision, Speech and Signal Processing and School of Biosciences and Medicine, The University of Surrey, Guildford, United Kingdom
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15
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Short-term changes in retinal and choroidal relative flow volume after anti-VEGF treatment for neovascular age-related macular degeneration. Sci Rep 2021; 11:23723. [PMID: 34887454 PMCID: PMC8660908 DOI: 10.1038/s41598-021-03179-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 10/25/2021] [Indexed: 11/29/2022] Open
Abstract
The effects of anti-vascular endothelial growth factor (anti-VEGF) agents on the native ocular vasculature are poorly understood. This pilot study aimed to assess short-term changes in retinal and choroidal perfusion after anti-VEGF treatment for neovascular exudative age-related macular degeneration (nAMD) using the relative flow volume (RFV) parameter derived from laser speckle flowgraphy. Ten treatment-naïve nAMD patients underwent measurements of mean, maximum, minimum, and differential RFV within a retinal arteriolar segment and a choroidal vessel segment outside the neovascular area. Measurement of retinal RFV (rRFV), choroidal RFV (cRFV), and subfoveal choroidal thickness (SCT) was repeated 9 and 35 days after a single anti-VEGF injection. The treatment caused a statistically significant decrease in the mean rRFV, mean cRFV, and SCT during the follow-up (p < 0.05). At the intermediate visit, the mean cRFV and SCT were − 17.6% and − 6.4% compared to baseline, respectively. However, at the final measurement, the mean cRFV was not different from the baseline value, which indicated waning of the anti-VEGF effect. In conclusion, a single anti-VEGF injection in treatment-naïve nAMD resulted in a decrease in retinal arteriolar and choroidal perfusion, according to the RFV parameter, which is a promising tool to simultaneously assess retinal and choroidal perfusion changes in response to anti-VEGF therapy.
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16
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Kallab M, Hommer N, Schlatter A, Bsteh G, Altmann P, Popa-Cherecheanu A, Pfister M, Werkmeister RM, Schmidl D, Schmetterer L, Garhöfer G. Retinal Oxygen Metabolism and Haemodynamics in Patients With Multiple Sclerosis and History of Optic Neuritis. Front Neurosci 2021; 15:761654. [PMID: 34712117 PMCID: PMC8546107 DOI: 10.3389/fnins.2021.761654] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 09/22/2021] [Indexed: 12/20/2022] Open
Abstract
Vascular changes and alterations of oxygen metabolism are suggested to be implicated in multiple sclerosis (MS) pathogenesis and progression. Recently developed in vivo retinal fundus imaging technologies provide now an opportunity to non-invasively assess metabolic changes in the neural retina. This study was performed to assess retinal oxygen metabolism, peripapillary capillary density (CD), large vessel density (LVD), retinal nerve fiber layer thickness (RNFLT) and ganglion cell inner plexiform layer thickness (GCIPLT) in patients with diagnosed relapsing multiple sclerosis (RMS) and history of unilateral optic neuritis (ON). 16 RMS patients and 18 healthy controls (HC) were included in this study. Retinal oxygen extraction was modeled using O2 saturations and Doppler optical coherence tomography (DOCT) derived retinal blood flow (RBF) data. CD and LVD were assessed using optical coherence tomography (OCT) angiography. RNFLT and GCIPLT were measured using structural OCT. Measurements were performed in eyes with (MS+ON) and without (MS-ON) history for ON in RMS patients and in one eye in HC. Total oxygen extraction was lowest in MS+ON (1.8 ± 0.2 μl O2/min), higher in MS-ON (2.1 ± 0.5 μl O2/min, p = 0.019 vs. MS+ON) and highest in HC eyes (2.3 ± 0.6 μl O2/min, p = 0.002 vs. MS, ANOVA p = 0.031). RBF was lower in MS+ON (33.2 ± 6.0 μl/min) compared to MS-ON (38.3 ± 4.6 μl/min, p = 0.005 vs. MS+ON) and HC eyes (37.2 ± 4.7 μl/min, p = 0.014 vs. MS+ON, ANOVA p = 0.010). CD, LVD, RNFLT and GCIPL were significantly lower in MS+ON eyes. The present data suggest that structural alterations in the retina of RMS patients are accompanied by changes in oxygen metabolism, which are more pronounced in MS+ON than in MS-ON eyes. Whether these alterations promote MS onset and progression or occur as consequence of disease warrants further investigation. Clinical Trial Registration: ClinicalTrials.gov registry, NCT03401879.
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Affiliation(s)
- Martin Kallab
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Nikolaus Hommer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Andreas Schlatter
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.,Vienna Institute for Research in Ocular Surgery (VIROS), Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria
| | - Gabriel Bsteh
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Patrick Altmann
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - Alina Popa-Cherecheanu
- Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.,Department of Ophthalmology, University Emergency Hospital, Bucharest, Romania
| | - Martin Pfister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Institute of Applied Physics, Vienna University of Technology, Vienna, Austria
| | - René M Werkmeister
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Leopold Schmetterer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.,Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Singapore Eye Research Institute, Singapore, Singapore.,Nanyang Technological University, Singapore, Singapore.,Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE), Singapore, Singapore.,Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
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17
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Tan B, Sim YC, Chua J, Yusufi D, Wong D, Yow AP, Chin C, Tan ACS, Sng CCA, Agrawal R, Gopal L, Sim R, Tan G, Lamoureux E, Schmetterer L. Developing a normative database for retinal perfusion using optical coherence tomography angiography. BIOMEDICAL OPTICS EXPRESS 2021; 12:4032-4045. [PMID: 34457397 PMCID: PMC8367249 DOI: 10.1364/boe.423469] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/13/2021] [Accepted: 05/13/2021] [Indexed: 05/25/2023]
Abstract
Visualizing and characterizing microvascular abnormalities with optical coherence tomography angiography (OCTA) has deepened our understanding of ocular diseases, such as glaucoma, diabetic retinopathy, and age-related macular degeneration. Two types of microvascular defects can be detected by OCTA: focal decrease because of localized absence and collapse of retinal capillaries, which is referred to as the non-perfusion area in OCTA, and diffuse perfusion decrease usually detected by comparing with healthy case-control groups. Wider OCTA allows for insights into peripheral retinal vascularity, but the heterogeneous perfusion distribution from the macula, parapapillary area to periphery hurdles the quantitative assessment. A normative database for OCTA could estimate how much individual's data deviate from the normal range, and where the deviations locate. Here, we acquired OCTA images using a swept-source OCT system and a 12×12 mm protocol in healthy subjects. We automatically segmented the large blood vessels with U-Net, corrected for anatomical factors such as the relative position of fovea and disc, and segmented the capillaries by a moving window scheme. A total of 195 eyes were included and divided into 4 age groups: < 30 (n=24) years old, 30-49 (n=28) years old, 50-69 (n=109) years old and >69 (n=34) years old. This provides an age-dependent normative database for characterizing retinal perfusion abnormalities in 12×12 mm OCTA images. The usefulness of the normative database was tested on two pathological groups: one with diabetic retinopathy; the other with glaucoma.
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Affiliation(s)
- Bingyao Tan
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore
- NTU Institute for Health Technologies, Singapore
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Yin Ci Sim
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Jacqueline Chua
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
- Duke-NUS Medical School, Singapore
| | - Dheo Yusufi
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Damon Wong
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore
- NTU Institute for Health Technologies, Singapore
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Ai Ping Yow
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore
- NTU Institute for Health Technologies, Singapore
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Calvin Chin
- Duke-NUS Medical School, Singapore
- National Heart Centre Singapore, Singapore
| | - Anna C. S. Tan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
- Duke-NUS Medical School, Singapore
- Changi General Hospital, Singapore
| | - Chelvin C. A. Sng
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
- Department of Ophthalmology, National University Hospital, Singapore
| | - Rupesh Agrawal
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
- Tan Tock Seng Hospital, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | | | - Ralene Sim
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Gavin Tan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
- Duke-NUS Medical School, Singapore
| | - Ecosse Lamoureux
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
- Duke-NUS Medical School, Singapore
| | - Leopold Schmetterer
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore
- NTU Institute for Health Technologies, Singapore
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore
- Department of Clinical Pharmacology, Medical University of Vienna, Austria
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
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18
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Dadkhah A, Paudel D, Jiao S. Comparative study of optical coherence tomography angiography algorithms for rodent retinal imaging. Exp Biol Med (Maywood) 2021; 246:2207-2213. [PMID: 34120494 DOI: 10.1177/15353702211024572] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Optical coherence tomography angiography (OCTA) is a functional extension of optical coherence tomography for non-invasive in vivo three-dimensional imaging of the microvasculature of biological tissues. Several algorithms have been developed to construct OCTA images from the measured optical coherence tomography signals. In this study, we compared the performance of three OCTA algorithms that are based on the variance of phase, amplitude, and the complex representations of the optical coherence tomography signals for rodent retinal imaging, namely the phase variance, improved speckle contrast, and optical microangiography. The performance of the different algorithms was evaluated by comparing the quality of the OCTA images regarding how well the vasculature network can be resolved. Quantities that are widely used in ophthalmic studies including blood vessel density, vessel diameter index, vessel perimeter index, vessel complexity index were also compared. Results showed that both the improved speckle contrast and optical microangiography algorithms are more robust than phase variance, and they can reveal similar vasculature features while there are statistical differences in the calculated quantities.
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Affiliation(s)
- Arash Dadkhah
- Department of Biomedical Engineering, 5450Florida International University, Miami, FL 33174, USA
| | - Dhruba Paudel
- Department of Biomedical Engineering, 5450Florida International University, Miami, FL 33174, USA
| | - Shuliang Jiao
- Department of Biomedical Engineering, 5450Florida International University, Miami, FL 33174, USA
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19
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Wong D, Chua J, Lin E, Tan B, Yao X, Chong R, Sng C, Lau A, Husain R, Aung T, Schmetterer L. Focal Structure-Function Relationships in Primary Open-Angle Glaucoma Using OCT and OCT-A Measurements. Invest Ophthalmol Vis Sci 2021; 61:33. [PMID: 33372979 PMCID: PMC7774057 DOI: 10.1167/iovs.61.14.33] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To evaluate the focal structure-function associations among visual field (VF) loss, optical coherence tomography angiography (OCT-A) vascular measurements, and optical coherence tomography (OCT) structural measurements in glaucoma. Methods In this cross-sectional study, subjects underwent standard automated perimetry, OCT-based nerve fiber thickness measurements, and OCT-A imaging. Mappings of focal VF test locations with OCT and OCT-A measurements were defined using anatomically adjusted nerve fiber trajectories and were studied using multivariate mixed-effects analysis. Segmented regression analysis was used to determine the presence of breakpoints in the structure-function associations. Results The study included 119 eyes from 86 Chinese subjects with primary open-angle glaucoma (POAG). VF mean deviation was significantly associated with global capillary perfusion density (β = 0.13 ± 0.08) and global retinal nerve fiber layer thickness (β = 0.09 ± 0.02). Focal capillary density (FCD) was significantly associated with VF losses at 34 VF test locations (66.7% of 24-2 VF), with 24 of the 34 locations being within 20° of retinal eccentricity. Focal nerve layer (FNL) thickness was significantly associated with 16 VF test locations (31.4% of 24-2 VF; eight locations within 20° eccentricity). For VF test locations in the central 10° VF, VF losses below the breakpoint were significantly associated with FCD (slope, 0.89 ± 0.12, P < 0.001), but not with FNL thickness (slope, 0.57 ± 0.39, P = 0.15). Conclusions Focal capillary densities were significantly associated with a wider range of visual field losses and in a larger proportion of the visual field compared to nerve fiber thickness.
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Affiliation(s)
- Damon Wong
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore.,NTU Institute of Health Technologies, Singapore.,Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Jacqueline Chua
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore
| | - Emily Lin
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Bingyao Tan
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore.,NTU Institute of Health Technologies, Singapore.,Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Xinwen Yao
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore.,NTU Institute of Health Technologies, Singapore.,Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Rachel Chong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Chelvin Sng
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,Ophthalmology Department, National University Hospital, Singapore
| | - Amanda Lau
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Rahat Husain
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Tin Aung
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,Academic Clinical Program, Duke-NUS Medical School, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Leopold Schmetterer
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore.,Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.,Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.,Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
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20
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Chua J, Ke M, Tan B, Gan ATL, Lim LS, Tan GS, Lee SY, Wong E, Schmetterer L, Cheung N. Association of macular and choroidal perfusion with long-term visual outcomes after macula-off rhegmatogenous retinal detachment. Br J Ophthalmol 2021; 106:1258-1263. [PMID: 33827859 DOI: 10.1136/bjophthalmol-2021-318907] [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] [Received: 01/20/2021] [Revised: 02/27/2021] [Accepted: 03/13/2021] [Indexed: 01/07/2023]
Abstract
BACKGROUND/AIMS To examine the relationship between macular perfusion, as assessed using optical coherence tomography angiography (OCTA), and long-term visual outcome after surgical repair of macula-off rhegmatogenous retinal detachment (RRD). METHODS A prospective study of 29 patients who had undergone successful surgical repair of macula-off RRD. OCTA imaging was performed at month 3 and repeated at months 6 and 12 after surgery. Associations between OCTA parameters including, foveal avascular zone (FAZ) area, vessel density (VD) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), choriocapillaris flow deficit features and logMAR best-corrected visual acuity (VA) were assessed using a random intercept hybrid linear mixed model. RESULTS Over the 1-year follow-up, VA improved (0.025 logMAR/ month, 95% CI 0.015 to 0.035) and FAZ area decreased (-0.020 mm2/month, 95% CI -0.032 to -0.007). Better VA after surgery was significantly associated with denser superficial VD (β=0.079, 95% CI 0.026 to 0.131), lower number of choriocapillaris flow deficits (β=-0.087, 95% CI -0.154 to -0.021) and larger average size of choriocapillaris flow deficits (β=0.085, 95% CI 0.022 to 0.147), after adjusting for baseline VA, types of surgery and other factors. CONCLUSIONS OCTA measures of vascular perfusion in the macula may provide new pathophysiological insights and prognostic information related to macula-off RRD.
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Affiliation(s)
- Jacqueline Chua
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.,Ophthalmology and Visual Sciences Academic Clinical Program, Duke-National University of Singapore Medical School, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE), Singapore
| | - Mengyuan Ke
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore
| | - Bingyao Tan
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore.,Institute for Health Technologies, Nanyang Technological University, Singapore
| | | | - Laurence S Lim
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-National University of Singapore Medical School, Singapore
| | - Gavin Sw Tan
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-National University of Singapore Medical School, Singapore
| | - Shu Yen Lee
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-National University of Singapore Medical School, Singapore
| | - Edmund Wong
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-National University of Singapore Medical School, Singapore
| | - Leopold Schmetterer
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-National University of Singapore Medical School, Singapore.,SERI-NTU Advanced Ocular Engineering (STANCE), Singapore.,Institute for Health Technologies, Nanyang Technological University, Singapore.,Department of Clinical Pharmacology, Medical University Vienna, Vienna, Austria.,Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria.,Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
| | - Ning Cheung
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-National University of Singapore Medical School, Singapore
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21
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Chua J, Sim R, Tan B, Wong D, Yao X, Liu X, Ting DSW, Schmidl D, Ang M, Garhöfer G, Schmetterer L. Optical Coherence Tomography Angiography in Diabetes and Diabetic Retinopathy. J Clin Med 2020; 9:E1723. [PMID: 32503234 PMCID: PMC7357089 DOI: 10.3390/jcm9061723] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 05/24/2020] [Accepted: 06/02/2020] [Indexed: 12/21/2022] Open
Abstract
Diabetic retinopathy (DR) is a common complication of diabetes mellitus that disrupts the retinal microvasculature and is a leading cause of vision loss globally. Recently, optical coherence tomography angiography (OCTA) has been developed to image the retinal microvasculature, by generating 3-dimensional images based on the motion contrast of circulating blood cells. OCTA offers numerous benefits over traditional fluorescein angiography in visualizing the retinal vasculature in that it is non-invasive and safer; while its depth-resolved ability makes it possible to visualize the finer capillaries of the retinal capillary plexuses and choriocapillaris. High-quality OCTA images have also enabled the visualization of features associated with DR, including microaneurysms and neovascularization and the quantification of alterations in retinal capillary and choriocapillaris, thereby suggesting a promising role for OCTA as an objective technology for accurate DR classification. Of interest is the potential of OCTA to examine the effect of DR on individual retinal layers, and to detect DR even before it is clinically detectable on fundus examination. We will focus the review on the clinical applicability of OCTA derived quantitative metrics that appear to be clinically relevant to the diagnosis, classification, and management of patients with diabetes or DR. Future studies with longitudinal design of multiethnic multicenter populations, as well as the inclusion of pertinent systemic information that may affect vascular changes, will improve our understanding on the benefit of OCTA biomarkers in the detection and progression of DR.
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Affiliation(s)
- Jacqueline Chua
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore; (J.C.); (R.S.); (B.T.); (D.W.); (X.Y.); (X.L.); (D.S.W.T.); (M.A.)
- Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore 639798, Singapore
| | - Ralene Sim
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore; (J.C.); (R.S.); (B.T.); (D.W.); (X.Y.); (X.L.); (D.S.W.T.); (M.A.)
| | - Bingyao Tan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore; (J.C.); (R.S.); (B.T.); (D.W.); (X.Y.); (X.L.); (D.S.W.T.); (M.A.)
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore 639798, Singapore
- Institute of Health Technologies, Nanyang Technological University, Singapore 639798, Singapore
| | - Damon Wong
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore; (J.C.); (R.S.); (B.T.); (D.W.); (X.Y.); (X.L.); (D.S.W.T.); (M.A.)
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore 639798, Singapore
- Institute of Health Technologies, Nanyang Technological University, Singapore 639798, Singapore
| | - Xinwen Yao
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore; (J.C.); (R.S.); (B.T.); (D.W.); (X.Y.); (X.L.); (D.S.W.T.); (M.A.)
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore 639798, Singapore
- Institute of Health Technologies, Nanyang Technological University, Singapore 639798, Singapore
| | - Xinyu Liu
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore; (J.C.); (R.S.); (B.T.); (D.W.); (X.Y.); (X.L.); (D.S.W.T.); (M.A.)
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore 639798, Singapore
| | - Daniel S. W. Ting
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore; (J.C.); (R.S.); (B.T.); (D.W.); (X.Y.); (X.L.); (D.S.W.T.); (M.A.)
- Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, 1090 Vienna, Austria; (D.S.); (G.G.)
| | - Marcus Ang
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore; (J.C.); (R.S.); (B.T.); (D.W.); (X.Y.); (X.L.); (D.S.W.T.); (M.A.)
- Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, 1090 Vienna, Austria; (D.S.); (G.G.)
| | - Leopold Schmetterer
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore 169856, Singapore; (J.C.); (R.S.); (B.T.); (D.W.); (X.Y.); (X.L.); (D.S.W.T.); (M.A.)
- Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
- SERI-NTU Advanced Ocular Engineering (STANCE), Singapore 639798, Singapore
- Institute of Health Technologies, Nanyang Technological University, Singapore 639798, Singapore
- Department of Clinical Pharmacology, Medical University of Vienna, 1090 Vienna, Austria; (D.S.); (G.G.)
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria
- Institute of Molecular and Clinical Ophthalmology, CH-4031 Basel, Switzerland
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