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Lee YJ, Hwang SY, Yun C. Flow Void Analysis Using Different Thresholding Methods on a Choriocapillaris Optical Coherence Tomography Angiography Image Complemented with a Structural En Face Image. KOREAN JOURNAL OF OPHTHALMOLOGY 2024; 38:34-41. [PMID: 38104595 PMCID: PMC10869421 DOI: 10.3341/kjo.2023.0110] [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: 09/27/2023] [Revised: 11/21/2023] [Accepted: 12/02/2023] [Indexed: 12/19/2023] Open
Abstract
PURPOSE To investigate the flow characteristics using different thresholding methods on a choriocapillaris optical coherence tomography angiography (OCTA) image complemented with a structural En Face image. METHODS The 42 choriocapillaris OCTA images from healthy subjects were obtained with swept-source OCTA device and the 3 × 3-mm area OCTA images were processed with ImageJ. Using a raw choriocapillaris OCTA image and structural En Face image, we adjusted the different structural signal intensity. Then, the raw images and adjusted images were binarized with a global threshold and an auto local threshold using the Phansalkar method at 1- or 2-intercapillary distance. Then, the mean area, number, and size of the flow void, were compared among the images using different thresholding methods. RESULTS Mean flow void area, number, and size were different according to the different binarization method both in raw and adjusted images (all p < 0.001). The mean flow void area analyzed with global threshold method were well correlated with those with auto local threshold method both in raw and adjusted images (all intraclass correlations, >0.929). CONCLUSIONS Flow void features varied according to the different binarization methods but showed good correlation. The flow void characteristics according to the different binarization methods should be considered for the analysis of the choriocapillaris OCTA images complemented with a structural En Face image.
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Affiliation(s)
- Young Joo Lee
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
| | - Soon-Young Hwang
- Department of Biostatistics, Korea University College of Medicine, Seoul, Korea
| | - Cheolmin Yun
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
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Verma A, Magesan K, Mahalingam M, T A, Sadda SR, Corradetti G, Alagorie AR, Gnanaraj R, Sen P. Age-Related Alterations of the Macular Choroid in Healthy Eyes Assessed by Swept-Source Optical Coherence Tomography Angiography. Ophthalmic Surg Lasers Imaging Retina 2023; 54:526-534. [PMID: 37642439 DOI: 10.3928/23258160-20230728-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
OBJECTIVE To analyze age-related changes in the choroid in healthy eyes using swept-source optical coherence tomography angiography (SS-OCTA). PATIENTS AND METHODS This was a cross-sectional, prospective, observational study enrolling 222 eyes of 116 healthy participants. SS-OCTA images were captured using the PLEX Elite 9000 (Carl Zeiss Meditec) with a 6 x 6 mm pattern centered on the fovea. Subfoveal choroidal thickness (CT) and choroidal volume (CV) were generated automatically through manufacturer tools available in the Advanced Retinal Imaging (ARI) hub network. Choroidal vascularity index (CVI) and choriocapillaris flow deficits (CCFD) were computed using ImageJ. RESULTS CV was found to be significantly higher in women than men. Overall, there was a significant positive correlation between CVI and CCFD, and a significant negative correlation between CT and CV with age. The relationship, however, was more complex, as a decade-wise analysis showed that CT and CV increased until the second decade, followed by a decrease until the sixth decade, and then an increase again in the seventh and eighth decades. CVI was highest in the seventh decade. In contrast, CCFD increased consistently with age and in all the Early Treatment of Diabetic Retinopathy Study (ETDRS) rings. CONCLUSION The choroidal blood flow and its thickness reduces as the age advances. While the choroidal flow deficits show a consistent increase with age and the distance from the foveal center, the relationship of other parameters with age is more complex. Having a normative database from healthy subjects is imperative for understanding the changes taking place in diseased states. Choroidal parameters can show significant variations with age. These differences are not uniform or consistent with age, highlighting the importance of a normative reference database to assess the significance of choroidal alterations associated with disease. [Ophthalmic Surg Lasers Imaging Retina 2023;54:526-534.].
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3
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Fogel Levin M, Santina A, Corradetti G, Au A, Lu A, Abraham N, Somisetty S, Romero Morales V, Wong A, Sadda S, Sarraf D. Pentosan Polysulfate Sodium-Associated Maculopathy: Early Detection Using OCT Angiography and Choriocapillaris Flow Deficit Analysis. Am J Ophthalmol 2022; 244:38-47. [PMID: 35901995 DOI: 10.1016/j.ajo.2022.07.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 07/18/2022] [Accepted: 07/18/2022] [Indexed: 01/30/2023]
Abstract
PURPOSE To compare choriocapillaris flow deficit (CC-FD) analysis using optical coherence tomography angiography (OCTA) in eyes of patients treated with high cumulative dosages of pentosan polysulfate sodium (PPS) but no signs of retinal toxicity versus healthy age-matched controls. DESIGN Retrospective clinical cohort study. METHODS Patients treated with PPS for interstitial cystitis with a cumulative dose of > 1000 g underwent multimodal imaging screening to exclude evidence of PPS maculopathy or other retinal findings. All study patients and age-matched healthy controls completed a 3 × 3 mm macular volume scan OCTA using the SOLIX full-range OCT. En face OCTA images at the level of the CC were exported and CC-FDs were computed and compared between groups. RESULTS Fifteen patients treated with PPS and 15 age-matched controls were included. The mean PPS cumulative dose was 1974 ± 666 g over a mean of 17.6 ± 6.8 treatment years. All patients registered a visual acuity of 20/25 or better and normal fundus autofluorescence (FAF), OCT, multicolor, near-infrared reflectance (NIR), and ultra-widefield fundus color and autofluorescence images. The CC-FD was 32.7 ± 3.6% in the PPS group compared with 28.6 ± 4.3% in the control group (P = .023). CONCLUSIONS Patients treated with PPS long enough to accumulate dosages > 1000 g showed significant CC flow impairment before the development of macular toxicity signs with OCT, NIR, and FAF compared with age-matched normal controls. Thus, the choroid may be the earliest manifestation of ocular toxicity, predating the development of clinically evident retinal pigment epithelium (RPE) injury. The subsequent RPE disruption may be the result of choriocapillaris impairment or primary PPS toxicity. Assessment of the CC on OCTA may be a useful tool for early detection of toxicity, although further longitudinal studies are required.
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Affiliation(s)
- Meira Fogel Levin
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S)
| | - Ahmad Santina
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S)
| | - Giulia Corradetti
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S); Doheny Eye Institute, Los Angeles, California, USA (G.C, S.V.S)
| | - Adrian Au
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S)
| | - Anthony Lu
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S)
| | - Neda Abraham
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S)
| | - Swathi Somisetty
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S)
| | - Veronica Romero Morales
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S)
| | - Alice Wong
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S)
| | - SriniVas Sadda
- Doheny Eye Institute, Los Angeles, California, USA (G.C, S.V.S); Department of Ophthalmology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California, USA (S.V.S)
| | - David Sarraf
- Stein Eye Institute, University of California-Los Angeles School of Medicine, Los Angeles, USA (M.F.L, A.S, G.C, A.A, A.L, N.A, S.S, V.R.M, A.W, D.S); Greater Los Angeles VA Healthcare Center, Los Angeles, California, USA (D.S).
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Wu Z, Zhou X, Chu Z, Gregori G, Wang RK, Rosenfeld PJ, Guymer RH. Impact of Reticular Pseudodrusen on Choriocapillaris Flow Deficits and Choroidal Structure on Optical Coherence Tomography Angiography. Invest Ophthalmol Vis Sci 2022; 63:1. [PMID: 36318196 PMCID: PMC9639673 DOI: 10.1167/iovs.63.12.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
PURPOSE To examine the impact of reticular pseudodrusen (RPD) on choriocapillaris blood flow and choroidal structure in individuals with intermediate age-related macular degeneration (AMD). METHODS Individuals with bilateral large drusen underwent optical coherence tomography (OCT), color fundus photography, near-infrared reflectance, and fundus autofluorescence imaging to determine the presence of RPD. These participants also underwent swept-source OCT angiography (SS-OCTA) imaging to determine (1) choriocapillaris flow deficit (FD) parameters, including the percentage, mean size, and number of FDs present; and (2) choroidal structural parameters, including mean choroidal thickness and choroidal vascularity index. Differences in these parameters between eyes with and without coexistent RPD were examined with and without adjustment for potential key confounders such as drusen volume from the SS-OCTA scans and age. RESULTS This study included 102 eyes from 51 individuals with bilateral large drusen, and the analyses showed that there were no significant differences in the choriocapillaris FD parameters (P ≥ 0.062 for all) and choroidal structural parameters (P ≥ 0.059 for all), with or without adjustment for potential confounders in this cohort. However, the percentage of FDs and the mean FD size were both significantly greater with increasing drusen volume (P ≤ 0.038 for both). CONCLUSIONS The coexistence of RPD in eyes of individuals with intermediate AMD was not associated with significant impairments in choriocapillaris blood flow and choroidal vascular structural changes, with or without adjustment for key confounders. These findings suggest that macular changes in these vascular parameters may not be associated with the presence of RPD.
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Affiliation(s)
- Zhichao Wu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia,Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Xiao Zhou
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Zhongdi Chu
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Giovanni Gregori
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Philip J. Rosenfeld
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Robyn H. Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia,Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
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Computerized Texture Analysis of Optical Coherence Tomography Angiography of Choriocapillaris in Normal Eyes of Young and Healthy Subjects. Cells 2022; 11:cells11121934. [PMID: 35741063 PMCID: PMC9221889 DOI: 10.3390/cells11121934] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/13/2022] [Accepted: 06/13/2022] [Indexed: 02/04/2023] Open
Abstract
Computerized texture analysis uses higher-order mathematics to identify patterns beyond what the naked eye can recognize. We tested its feasibility in optical coherence tomography angiography imaging of choriocapillaris. Our objective was to determine sets of parameters that provide coherent and consistent output when applied to a homogeneous, healthy group of patients. This observational cross-sectional study involved 19 eyes of 10 young and healthy Caucasian subjects. En-face macular optical coherence tomography angiography of superficial choriocapillaris was obtained by the RTVue-XR Avanti system. Various algorithms were used to extract texture features. The mean and standard deviation were used to assess the distribution and dispersion of data points in each metric among eyes, which included: average gray level, gray level yielding 70% threshold and 30% threshold, balance, skewness, energy, entropy, contrast, edge mean gradient, root-mean-square variation, and first moment of power spectrum, which was compared between images, showing a highly concordant homology between all eyes of participants. We conclude that computerized texture analysis for en-face optical coherence tomography angiography images of choriocapillaris is feasible and provides values that are coherent and tightly distributed around the mean in a homogenous, healthy group of patients. Homology of blob size among subjects may represent a “repeat pattern” in signal density and thus a perfusion in the superficial choriocapillaris of healthy young individuals of the same ethnic background.
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Loria O, Kodjikian L, Denis P, Vartin C, Dimassi S, Gervolino L, Maignan A, Kermarrec R, Chambard C, Pradat P, Mathis T. QUANTITATIVE ANALYSIS OF CHORIOCAPILLARIS ALTERATIONS IN SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN DIABETIC PATIENTS. Retina 2021; 41:1809-1818. [PMID: 33411469 DOI: 10.1097/iae.0000000000003102] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
PURPOSE To evaluate quantitative alterations of the choriocapillaris in swept-source optical coherence tomography angiography in diabetic patients. METHODS We included normal patients and diabetic patients with and without diabetic retinopathy (DR), excluding patients with macular edema. Angiograms in 3 × 3 mm were acquired with Plexelite 9000 swept-source optical coherence tomography angiography. Choroidal flow voids were analyzed after removal of projection artifacts. The main evaluation was the correlation between choroidal flow voids area (FVA-CC) and DR stage. RESULTS A total of 120 eyes of 72 patients were analyzed. There were 17 eyes from healthy subjects, 30 eyes without DR, 22 eyes with minimal nonproliferative DR, 30 eyes with moderate nonproliferative DR, 16 eyes with severe nonproliferative DR, and 5 eyes with proliferative DR (PDR). The percentage of FVA-CC for each group was, respectively, 10.9 ± 3.4%, 14.6 ± 4.8%, 17.6 ± 3.5%, 20.7 ± 5.9%, 19.9 ± 2.9%, and 26.6 ± 4.4%. FVA-CC and DR stage significantly correlated (P < 0.0001). FVA-CC was significantly increased in diabetic patients without DR compared with healthy subjects (P = 0.008). CONCLUSION Diabetes is associated with quantifiable choriocapillaris alterations in swept-source optical coherence tomography angiography. These alterations precede clinical signs of DR and are correlated with DR stage.
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Affiliation(s)
- Olivier Loria
- Service d'Ophtalmologie, Hôpital universitaire de la Croix-Rousse, Hospices Civils de Lyon, France
| | - Laurent Kodjikian
- Service d'Ophtalmologie, Hôpital universitaire de la Croix-Rousse, Hospices Civils de Lyon, France
- Laboratoire UMR-CNRS 5510 Matéis, Villeurbane, France
| | - Philippe Denis
- Service d'Ophtalmologie, Hôpital universitaire de la Croix-Rousse, Hospices Civils de Lyon, France
| | - Christine Vartin
- Service d'Ophtalmologie, Hôpital universitaire de la Croix-Rousse, Hospices Civils de Lyon, France
| | - Sarra Dimassi
- Service d'Ophtalmologie, Groupe Hospitalier Public Sud de l'Oise, Creil, France
| | - Lucas Gervolino
- Institut des Sciences et Techniques de la Réadaptation-Orthoptie, Lyon, France; and
| | - Antoine Maignan
- Institut des Sciences et Techniques de la Réadaptation-Orthoptie, Lyon, France; and
| | - Ronan Kermarrec
- Institut des Sciences et Techniques de la Réadaptation-Orthoptie, Lyon, France; and
| | - Claudine Chambard
- Service d'Ophtalmologie, Hôpital universitaire de la Croix-Rousse, Hospices Civils de Lyon, France
- Institut des Sciences et Techniques de la Réadaptation-Orthoptie, Lyon, France; and
| | - Pierre Pradat
- Centre de Recherche Clinique, Hôpital universitaire de la Croix-Rousse, Hospices Civils de Lyon, France
| | - Thibaud Mathis
- Service d'Ophtalmologie, Hôpital universitaire de la Croix-Rousse, Hospices Civils de Lyon, France
- Laboratoire UMR-CNRS 5510 Matéis, Villeurbane, France
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7
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Ng DSC, Chan LKY, Ng CM, Lai TYY. Visualising the choriocapillaris: Histology, imaging modalities and clinical research - A review. Clin Exp Ophthalmol 2021; 50:91-103. [PMID: 34387023 DOI: 10.1111/ceo.13984] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 08/09/2021] [Indexed: 01/02/2023]
Abstract
The choriocapillaris plays a considerable role in the normal physiology of the eye as well as in various diseases. Assessing the changes in the choriocapillaris can therefore provide important information about normal ageing and pathogenesis of visual impairment, and even some systemic diseases. In vivo imaging of the choriocapillaris has evolved from non-depth resolved, dye-based angiography to advanced, high-resolution optical coherence tomography angiography (OCTA). However, the intricate microvascular networks within the choriocapillaris are still beyond the resolving limits of most OCTA instruments. Knowledge of histology, meticulous image acquisition methods, recognition of artefact and post-acquisition processing techniques are necessary for optimising OCTA choriocapillaris images. Qualitative and quantitative analyses of the choriocapillaris provide clinical information in age-related macular degeneration (AMD), diabetic retinopathy (DR), pathologic myopia and central serous chorioretinopathy (CSC). Furthermore, studies have revealed choriocapillaris changes in posterior uveitis that are correlated with treatment outcome and have important prognostic significance. In addition to retinal diseases, choriocapillaris changes have been observed in systemic vascular diseases and complications associated with pregnancy.
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Affiliation(s)
- Danny Siu-Chun Ng
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.,Hong Kong Eye Hospital, Mong Kok, Hong Kong
| | - Leo Ka-Yu Chan
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.,Hong Kong Eye Hospital, Mong Kok, Hong Kong
| | - Ching Man Ng
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Timothy Y Y Lai
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.,2010 Retina & Macula Centre, Kowloon, Hong Kong
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8
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Moult EM, Shi Y, Zhang Q, Wang L, Mazumder R, Chen S, Chu Z, Feuer W, Waheed NK, Gregori G, Wang RK, Rosenfeld PJ, Fujimoto JG. Analysis of correlations between local geographic atrophy growth rates and local OCT angiography-measured choriocapillaris flow deficits. BIOMEDICAL OPTICS EXPRESS 2021; 12:4573-4595. [PMID: 34457433 PMCID: PMC8367222 DOI: 10.1364/boe.427819] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/21/2021] [Accepted: 06/26/2021] [Indexed: 06/13/2023]
Abstract
The purpose of this study is to quantitatively assess correlations between local geographic atrophy (GA) growth rates and local optical coherence tomography angiography (OCTA)-measured choriocapillaris (CC) flow deficits. Thirty-eight eyes from 27 patients with GA secondary to age-related macular degeneration (AMD) were imaged with a commercial 1050 nm swept-source OCTA instrument at 3 visits, each separated by ∼6 months. Pearson correlations were computed between local GA growth rates, estimated using a biophysical GA growth model, and local OCTA CC flow deficit percentages measured along the GA margins of the baseline visits. The p-values associated with the null hypothesis of no Pearson correlation were estimated using a Monte Carlo permutation scheme that incorporates the effects of spatial autocorrelation. The null hypothesis (Pearson's ρ = 0) was rejected at a Benjamini-Hochberg false discovery rate of 0.2 in 15 of the 114 visit pairs, 11 of which exhibited positive correlations; even amongst these 11 visit pairs, correlations were modest (r in [0.30, 0.53]). The presented framework appears well suited to evaluating other potential imaging biomarkers of local GA growth rates.
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Affiliation(s)
- Eric M. Moult
- Department of Electrical Engineering and
Computer Science, Research Laboratory of Electronics,
Massachusetts Institute of Technology,
Cambridge, MA 02139-4307, USA
- Health Sciences and Technology,
Harvard & Massachusetts Institute of
Technology, Cambridge, MA 02139-4307, USA
| | - Yingying Shi
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - Qinqin Zhang
- Department of Bioengineering,
University of Washington, Seattle, WA
98104, USA
| | - Liang Wang
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - Rahul Mazumder
- Sloan School of Management, Operations
Research Center and Center for Statistics, Massachusetts
Institute of Technology, Cambridge, MA 02139-4307,
USA
| | - Siyu Chen
- Department of Electrical Engineering and
Computer Science, Research Laboratory of Electronics,
Massachusetts Institute of Technology,
Cambridge, MA 02139-4307, USA
| | - Zhongdi Chu
- Department of Bioengineering,
University of Washington, Seattle, WA
98104, USA
| | - William Feuer
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - Nadia K. Waheed
- New England Eye
Center, Tufts Medical Center, Boston, MA 02111, USA
| | - Giovanni Gregori
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - Ruikang K. Wang
- Department of Bioengineering,
University of Washington, Seattle, WA
98104, USA
| | - Philip J. Rosenfeld
- Department of Ophthalmology, Bascom Palmer
Eye Institute, University of Miami Miller School of
Medicine, Miami, FL 33136, USA
| | - James G. Fujimoto
- Department of Electrical Engineering and
Computer Science, Research Laboratory of Electronics,
Massachusetts Institute of Technology,
Cambridge, MA 02139-4307, USA
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Shi Y, Zhang Q, Zhou H, Wang L, Chu Z, Jiang X, Shen M, Thulliez M, Lyu C, Feuer W, de Sisternes L, Durbin MK, Gregori G, Wang RK, Rosenfeld PJ. Correlations Between Choriocapillaris and Choroidal Measurements and the Growth of Geographic Atrophy Using Swept Source OCT Imaging. Am J Ophthalmol 2021; 224:321-331. [PMID: 33359715 DOI: 10.1016/j.ajo.2020.12.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 09/20/2020] [Accepted: 12/15/2020] [Indexed: 01/07/2023]
Abstract
PURPOSE Correlations among enlargement rates (ERs) of geographic atrophy (GA) and choriocapillaris (CC) flow deficits (FDs), mean choroidal thickness (MCT), and choroidal vascularity index (CVI) were investigated using swept source-optical coherence tomography (SS-OCT) in age-related macular degeneration (AMD). DESIGN A retrospective review of prospective, observational case series. METHODS Eyes with GA from AMD were imaged with SS-OCT using 6 × 6-mm scan pattern. GA lesions were identified and measured using customized en face structural images, and annual square root ERs of GA were calculated. At baseline, choriocapillaris FDs from different regions outside the GA were measured, and MCT and CVI from the entire scan area were measured. All measurements were performed using previously published and validated algorithms. RESULTS A total of 38 eyes from 27 patients were included. The CC FDs within each region around GA lesions were highly correlated with ERs of GA (all P < .005). CVI inside the GA region was correlated with the ERs (P = .03), whereas other choroidal measurements had no significant correlation with the ERs of GA (P > .06). CONCLUSIONS Statistically significant correlations were found between the ERs of GA and CC percentage of FD (FD%) from the entire scan region outside the GA and not just the region immediately adjacent to the GA. These results suggest that abnormal CC perfusion throughout the macula contributes to disease progression in eyes with GA. CVI inside the GA region could also be a potential indicator for the growth of GA.
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10
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Fasolino G, Awada G, Koulalis JS, Neyns B, Van Elderen P, Kuijpers RW, Nelis P, Ten Tusscher M. Choriocapillaris Assessment In Patients Under Mek-Inhibitor Therapy For Cutaneous Melanoma: An Optical Coherence Tomography Angiography Study. Semin Ophthalmol 2021; 36:765-771. [PMID: 33755528 DOI: 10.1080/08820538.2021.1903512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
PURPOSE The present study investigates by optical coherence tomography angiography (OCTA) the retinal capillary plexus and choriocapillaris flow voids and their possible correlation with MEKAR. METHODS 34 eyes of 17 patients (61.5 years [30.4-77.4]) with stage IV cutaneous melanoma were included prospectively. All patients showed disease progression under treatment with Nivolumab/Ipilimumab and were subsequently treated with the MEK-inhibitor Trametinib 2 mg once daily. At the start and every 6 weeks during follow-up of 4 months, patients underwent a complete ophthalmologic exam, OCTA and when needed fluorescein angiography. RESULTS Statistical analysis was performed on 17 eyes of 9 patients. Eight patients were excluded due to missing OCTA images or due to drop-out because of decease or change of treatment. Comparing vessel area density (P = .625 and 0.681, respectively), vessel skeleton density (P = .996 and 0.766, respectively) of the superficial and deep capillary plexus, flow void number and total flow void area (mm2 and %) (P = .495; 0.197 and 0.298, respectively) of choriocapillaris slab, before and after treatment, revealed no significant difference. The evolution of choriocapillaris flow void parameter did not significantly differ in patients, who developed MEKAR compared to patients who did not. CONCLUSION In patients receiving MEK-inhibitor with and without MEKAR, no significant different characteristics of the retinal capillary plexus and choriocapillaris were found. These data suggest that the development of MEKAR, has no correlation with vascular alteration.
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Affiliation(s)
- Giuseppe Fasolino
- Department of Ophthalmology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Gil Awada
- Department of Oncology, Vrije Universiteit Brussel, Brussels, Belgium
| | | | - Bart Neyns
- Department of Oncology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Peter Van Elderen
- Department of Ophthalmology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Robert W Kuijpers
- Department of Ophthalmology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Pieter Nelis
- Department of Ophthalmology, Vrije Universiteit Brussel, Brussels, Belgium.,Department of Ophthalmology, University of Muenster Medical Center, Muenster, Germany
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Cheng Y, Chu Z, Wang RK. Robust three-dimensional registration on optical coherence tomography angiography for speckle reduction and visualization. Quant Imaging Med Surg 2021; 11:879-894. [PMID: 33654662 PMCID: PMC7829160 DOI: 10.21037/qims-20-751] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 08/18/2020] [Indexed: 11/06/2022]
Abstract
BACKGROUND In the clinical applications of optical coherence tomography angiography (OCTA), the repeated scanning and averaging method can provide better contrast with reduced speckle noises in the final results, which are useful for visualizing and quantifying vascular components with high accuracy, reproducibility, and reliability. However, the inevitable patient motion presents a challenge to this method. The objective of this study is to meet this challenge by introducing a 3D registration method to register optical coherence tomography (OCT)/OCTA scans for precise volume averaging of multiple scans to improve the signal-to-noise ratio (SNR) and increase quantification accuracy. METHODS The proposed method utilized both rigid affine transformation and non-rigid B-spline transformation in which their parameters were optimized and calculated by the average stochastic gradient descent on OCT structural images. In addition, we also introduced a multi-level resolution approach to further improve the robustness and computational speed of our proposed method. The imaging performance was tested on in vivo imaging of human skin and eye and assessed by SNR, peak signal-to-noise ratio (PSNR) and normalized correlation coefficient (NCC). RESULTS Five subjects were enrolled in this study for obtaining in vivo images of skin and retina. The proposed registration and averaging method provided substantial improvements of the imaging performance in terms of vessel connectivity and signal to noise ratio. The increase of repeated volume numbers in the averaging improves all the metrics assessed, i.e., SNR, PSNR and NCC. An improvement of the SNR from 10 to 40 dB after 10 repeated volumetric averaging was achieved. CONCLUSIONS The proposed 3D registration and averaging method is effective in reducing speckle noises and suppressing motion artifacts, thereby improving SNR, PSNR and NCC metrics for final averaged images. It is expected that the proposed algorithm would be practically useful in better visualization and more reliable quantification of in vivo OCT and OCTA data, which would be beneficial to OCT clinical applications.
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Affiliation(s)
- Yuxuan Cheng
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Zhongdi Chu
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
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12
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Yang Y, Zhang G, Zhang S, Bian X, Qi L, Guo S, Zhang B, Liu L. Quantitative Analysis of the Macular and Peripapillary Capillary Network with Optical Coherence Tomography Angiography in Chinese Adolescents: The Tuyou County Pediatric Eye (TYPE) Study. Int J Gen Med 2021; 14:371-379. [PMID: 33574695 PMCID: PMC7872928 DOI: 10.2147/ijgm.s293560] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 01/14/2021] [Indexed: 12/18/2022] Open
Abstract
Aim To use OCTA to collect normative data describing the vascular perfusion of the macula and optic disc in adolescents. Methods This cross-sectional, school-based study was conducted from Oct 15, 2019, to Nov 30, 2019, in Tuyou County, Baotou, China. All eligible participants underwent a comprehensive questionnaire and ocular examination. The vascular perfusion of the macula and optic disc was determined using a spectral-domain OCTA device. Results A total of 570 anatomically normal eyes without a history of pathologic disease from 570 adolescents (mean ± SD age, 15.1 ± 1.9 years; 298 girls [52.3%]) were enrolled. In the macula, the mean ± SD perifoveal perfusion density (PD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) was 44.2% ± 4.37% and 50.74% ± 3.98%, respectively. The mean ± SD foveal avascular zone (FAZ) was 0.32 mm2 ± 0.11 mm2. The mean ± SD peripapillary vessel density (PVD) was 54.98% ± 3.53%. The inferior hemiretinal SCP-PD, DCP-PD, FAZ, and PVD was larger in girls than boys (P = 0.006, P = 0.001, P < 0.001, and P = 0.006, respectively) Multiple regression analysis confirmed that sex independently affected the DCP-PD, FAZ, and PVD (P < 0.001, P < 0.001, and P = 0.029, respectively) and that axial length (AL) independently affected the FAZ area and PVD (P = 0.004 and P < 0.001, respectively). Conclusion Quantitative studies of the perifoveal vasculature in adolescents should consider the patient’s sex and AL. Our findings may provide useful information for the understanding and the management of retinal perfusion in Chinese adolescents.
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Affiliation(s)
- Yajun Yang
- Cataract Department, Baotou Chaoju Eye Hospital, Baotou, 014060, People's Republic of China
| | - Guisen Zhang
- Retina Department, Hohhot Chaoju Eye Hospital, Hohhot, 010050, People's Republic of China
| | - Song Zhang
- Cataract Department, China Medical University, Shenyang, 110122, People's Republic of China
| | - Xiaoyan Bian
- Cataract Department, Baotou Chaoju Eye Hospital, Baotou, 014060, People's Republic of China
| | - Lao Qi
- Retina Department, Hohhot Chaoju Eye Hospital, Hohhot, 010050, People's Republic of China
| | - Shixuan Guo
- Retina Department, Hohhot Chaoju Eye Hospital, Hohhot, 010050, People's Republic of China
| | - Bozhou Zhang
- Cataract Department, Baotou Chaoju Eye Hospital, Baotou, 014060, People's Republic of China
| | - Lei Liu
- Department of Ophthalmology, The First Affiliated Hospital of China Medical University, Shenyang, 110001, People's Republic of China
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13
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Chu Z, Zhang Q, Gregori G, Rosenfeld PJ, Wang RK. Guidelines for Imaging the Choriocapillaris Using OCT Angiography. Am J Ophthalmol 2021; 222:92-101. [PMID: 32891694 DOI: 10.1016/j.ajo.2020.08.045] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/12/2020] [Accepted: 08/28/2020] [Indexed: 01/23/2023]
Abstract
PURPOSE To provide guidance on how to appropriately quantitate various choriocapillaris (CC) parameters with optical coherence tomography angiography (OCTA). DESIGN Evidence-based perspective. METHODS Review of literature and experience of authors. RESULTS Accurate and reliable quantification of CC using OCTA requires that CC can be visualized and that the measurements of various CC parameters are validated. For accurate visualization, the selected CC slab must be physiologically sound, must produce images consistent with histology, and must yield qualitatively similar images when viewing repeats of the same scan or scans of different sizes. For accurate quantification, the measured intercapillary distances (ICDs) should be consistent with known measurements using histology and adaptive optics and/or OCTA, the selected CC parameters must be physiologically and physically meaningful based on the resolution of the instrument and the density of the scans, the selected algorithm for CC binarization must be appropriate and generate meaningful results, and the CC measurements calculated from multiple scans of the same and different sizes should be quantitatively similar. If the Phansalkar local thresholding method is used, then its parameters must be optimized for CC based on the OCTA instrument and scan patterns used. It is recommended that the window radius used in the Phansalkar method should be related to the expected average ICD in normal eyes. CONCLUSIONS Quantitative analysis of CC using commercially available OCTA instruments is complicated, and researchers need to tailor their strategies based on the instrument, scan patterns, anatomy, and thresholding strategies to achieve accurate and reliable measurements.
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14
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Shi Y, Chu Z, Wang L, Zhang Q, Feuer W, de Sisternes L, Durbin MK, Gregori G, Wang RK, Rosenfeld PJ. Validation of a Compensation Strategy Used to Detect Choriocapillaris Flow Deficits Under Drusen With Swept Source OCT Angiography. Am J Ophthalmol 2020; 220:115-127. [PMID: 32621895 DOI: 10.1016/j.ajo.2020.06.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/14/2020] [Accepted: 06/19/2020] [Indexed: 12/19/2022]
Abstract
PURPOSE A compensation strategy that was developed to measure the choriocapillaris (CC) flow deficits (FDs) under drusen was tested in eyes with large drusen from age-related macular degeneration (AMD) before and after the drusen spontaneously resolved without evidence of disease progression. DESIGN Prospective, observational consecutive case series. METHODS Patients with AMD were enrolled in a prospective swept-source optical coherence tomography (SS-OCT) imaging study. Consecutive eyes with large drusen were followed, and eyes that underwent spontaneous collapse of drusen without evidence of disease progression were identified retrospectively. The drusen-resolved regions were manually outlined. CC FDs were measured using a previously published compensation strategy that adjusted for the decreased signal intensity underlying drusen. Both the percentage of FDs (FD%) and the mean FD sizes (MFDSs) were measured before and after drusen resolution. RESULTS Resolution of drusen was identified in 8 eyes from 8 patients. The average interval between the 2 visits was 7.8 months. The average drusen volumes measured between visits were 0.23 and 0.04 mm3, respectively. After the drusen resolved, the average follow-up time without evidence of disease progression was 10.1 months. When the 2 visits were compared, there were no statistically significant differences in any of the CC parameters within the drusen resolved regions once the compensation strategy was applied (all P values >.22). CONCLUSIONS In this naturally occurring experiment in which drusen collapsed without evidence of disease progression, the CC parameters were similar once our compensation strategy was applied both before and after the drusen resolved.
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Affiliation(s)
- Yingying Shi
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Zhongdi Chu
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Liang Wang
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Qinqin Zhang
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - William Feuer
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Luis de Sisternes
- Research and Development, Carl Zeiss Meditec, Inc, Dublin, California, USA
| | - Mary K Durbin
- Research and Development, Carl Zeiss Meditec, Inc, Dublin, California, USA
| | - Giovanni Gregori
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Philip J Rosenfeld
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA.
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15
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Mendonça LSM, Levine ES, Waheed NK. Can the Onset of Neovascular Age-Related Macular Degeneration Be an Acceptable Endpoint for Prophylactic Clinical Trials? Ophthalmologica 2020; 244:379-386. [PMID: 33197919 DOI: 10.1159/000513083] [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: 04/30/2020] [Accepted: 10/22/2020] [Indexed: 11/19/2022]
Abstract
Many studies over the past 20 years have pursued the goal of preventing or deferring progression from early and intermediate age-related macular degeneration (AMD) to advanced AMD. The onset of neovascular AMD has been used as a primary endpoint in some prophylactic clinical trials because it is easy to assess and relatively well-defined. Nevertheless, the use of this endpoint for assessing progression of AMD lacks validation. The aims of this paper are to review the current practice of clinical trials investigating the prevention of progression of early or intermediate AMD to neovascular AMD, so-called prophylactic trials, as well as identify ongoing efforts to standardize endpoints and select the ideal population for such studies.
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Affiliation(s)
- Luísa S M Mendonça
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts, USA.,Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | - Emily S Levine
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts, USA.,Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Nadia K Waheed
- New England Eye Center, Tufts Medical Center, Boston, Massachusetts, USA,
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16
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Laiginhas R, Cabral D, Falcão M. Evaluation of the different thresholding strategies for quantifying choriocapillaris using optical coherence tomography angiography. Quant Imaging Med Surg 2020; 10:1994-2005. [PMID: 33014731 PMCID: PMC7495317 DOI: 10.21037/qims-20-340] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 07/03/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND In this paper, we evaluate the different thresholding strategies that have been used for the quantification of the choriocapillaris (CC) and explore their repeatability and the interchangeability of the measurements resulting from its application. METHODS Observational study. Eighteen eyes from nine healthy volunteers aged >18 years were imaged four consecutive times with a SD-OCTA system (Heidelberg Engineering, Germany) using a 10°×10° high-resolution protocol centered on the fovea. Projection artifacts were removed, and the CC was bracketed between 10 and 30 µm below Bruch's membrane. For the quantification of CC, we used four flow deficits (FD) parameters: FD number, mean FD size, total FD area and FD density. We performed a systematic review of literature to collect the thresholding methods that have been used for the quantification of CC. The CC quantification parameters were then evaluated after applying each of the thresholding strategies. Intraclass correlation coefficient (ICC) and Pearson's correlation analysis were used to compare the repeatability and interchangeability among the different thresholding strategies for quantifying the CC. RESULTS A total of 72 optical coherence tomography angiography (OCTA) examinations were considered. The systematic review allowed us to conclude that three local thresholding strategies (Phansalkar, mean and Niblack) and three global thresholding strategies (mean, default, Otsu) have been used for CC quantification. These strategies were evaluated in our observational study. We found a high agreement within the same method in the quantification of FD number, mean FD size, total FD area and FD density but a poor agreement with different strategies. Local strategies achieved a significantly superior ICC than global ones in CC quantification. CONCLUSIONS In conclusion, the interchangeability of the CC quantification using different thresholding strategies is low, and direct comparisons should not be performed. Local thresholding strategies are significantly superior to global ones for quantifying CC and should be preferred. There is an unmet need for a uniform strategy to quantify CC in future studies.
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Affiliation(s)
- Rita Laiginhas
- Department of Ophthalmology, CHEDV, Portugal
- PDICSS, Faculty of Medicine of the University of Porto, Porto, Portugal
| | - Diogo Cabral
- CEDOC, NOVA Medical School I Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisbon, Portugal
- Instituto de Oftalmologia Dr. Gama Pinto, Lisboa, Portugal
| | - Manuel Falcão
- Department of Ophthalmology, Centro Hospitalar e Universitário de São João, Porto, Portugal
- Department of Surgery and Physiology, Faculty of Medicine of the University of Porto, Porto, Portugal
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17
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Braun PX, Mehta N, Gendelman I, Alibhai AY, Baumal CR, Duker JS, Waheed NK. Using the Pathophysiology of Dry AMD to Guide Binarization of the Choriocapillaris on OCTA: A Model. Transl Vis Sci Technol 2020; 9:44. [PMID: 32855890 PMCID: PMC7422830 DOI: 10.1167/tvst.9.8.44] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 06/02/2020] [Indexed: 12/02/2022] Open
Abstract
Especially since the incorporation of swept laser sources, optical coherence tomography angiography (OCTA) has enabled quantification of choriocapillaris perfusion. A critical step in this process is binarization, which makes angiographic images quantifiable in terms of perfusion metrics. It remains challenging to have confidence that choriocapillaris perfusion metrics reflect the reality of pathophysiologic flow, largely because choice of binarization method can result in significantly different perfusion metric outcomes. This commentary discusses a proof-of-concept case involving comparative assessment of binarization methods for a set of dry age-related macular degeneration OCTA data. One of these methods was deemed preferable based on superior agreement with suspected physiologic and pathophysiologic characteristics, thus demonstrating the principle that, in the absence of gold standards for measurement of choriocapillaris perfusion, the best available approximations of pathophysiology may be used to guide choice of binarization method.
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Affiliation(s)
- Phillip X Braun
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, USA
| | - Nihaal Mehta
- Department of Ophthalmology, University of Colorado, Denver, CO, USA
| | - Isaac Gendelman
- Department of Surgery, Tufts Medical Center, Boston, MA, USA
| | - A Yasin Alibhai
- New England Eye Center, Tufts Medical Center, Boston, MA, USA
| | | | - Jay S Duker
- New England Eye Center, Tufts Medical Center, Boston, MA, USA
| | - Nadia K Waheed
- New England Eye Center, Tufts Medical Center, Boston, MA, USA
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18
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Chu Z, Cheng Y, Zhang Q, Zhou H, Dai Y, Shi Y, Gregori G, Rosenfeld PJ, Wang RK. Quantification of Choriocapillaris with Phansalkar Local Thresholding: Pitfalls to Avoid. Am J Ophthalmol 2020; 213:161-176. [PMID: 32059979 DOI: 10.1016/j.ajo.2020.02.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 01/31/2020] [Accepted: 02/01/2020] [Indexed: 01/01/2023]
Abstract
PURPOSE To demonstrate the proper use of the Phansalkar local thresholding method (Phansalkar method) in choriocapillaris (CC) quantification with optical coherence tomography angiography (OCTA). DESIGN Retrospective, observational case series. METHODS Swept source OCTA imaging was performed using 3×3 mm and 6×6 mm scanning patterns. The CC slab was extracted after semiautomatic segmentation of the retinal pigment epithelium/Bruch membrane complex. Retinal projection artifacts were removed before further analysis, and CC OCTA images from drusen eyes were compensated using a previously published strategy. CC flow deficits (FDs) were segmented with 2 previously published algorithms: the fuzzy C-means approach (FCM method) and the Phansalkar method. With the Phansalkar method, different parameters were tested and a local window radius of 1 to 15 pixels was used. FD density, mean FD size, and FD number were calculated for comparison. RESULTS Six normal eyes from 6 subjects and 6 eyes with drusen secondary to age-related macular degeneration from 6 subjects were analyzed. With both 3×3 mm and 6×6 mm scans from all eyes, the FD metrics were highly dependent on the selection of the local window radius when using the Phansalkar method. Larger window radii resulted in higher FD density values. FD number increased with the increase in the window radius but then decreased, with an inflection point at about 1 to 2 intercapillary distances. Mean FD size decreased then increased with increasing window radii. CONCLUSIONS Multiple parameters, especially the local window radius, should be optimized before using the Phansalkar method for the quantification of CC FDs with OCTA imaging. It is recommended that the proper use of the Phansalkar method should include the selection of the window radius that is related to the expected intercapillary distance in normal eyes.
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Affiliation(s)
- Zhongdi Chu
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Yuxuan Cheng
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Qinqin Zhang
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Hao Zhou
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Yining Dai
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Yingying Shi
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Giovanni Gregori
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Philip J Rosenfeld
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, Washington, USA; Department of Ophthalmology, University of Washington, Seattle, Washington, USA.
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19
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Chu Z, Gregori G, Rosenfeld PJ, Wang RK. Quantification of Choriocapillaris with Optical Coherence Tomography Angiography: A Comparison Study. Am J Ophthalmol 2019; 208:111-123. [PMID: 31323202 DOI: 10.1016/j.ajo.2019.07.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/19/2019] [Accepted: 07/11/2019] [Indexed: 12/19/2022]
Abstract
PURPOSE To demonstrate the variation in quantitative choriocapillaris (CC) metrics with various binarization approaches using optical coherence tomography angiography (OCTA). DESIGN Retrospective, observational, cross-sectional case series. METHODS Macular OCTA scans, 3- × 3-mm and 6- × 6-mm, were obtained from normal eyes and from eyes with drusen secondary to age-related macular degeneration (AMD). The CC slab was extracted, and the CC flow deficits (FDs) were segmented with 2 previously published algorithms: the fuzzy C-means approach (FCM method) and Phansalkar's local thresholding (Phansalkar method). Four different values for the radius were used in order to investigate the effect on the FD segmentation when using the Phansalkar method. FD density (FDD), mean FD size (MFDS), FD number (FDN), FD area (FDA) and intercapillary distance (ICD) were calculated for comparison. Repeatability was assessed as coefficient of variation (CV), and Pearson's correlation analysis was conducted. RESULTS Six eyes from 6 subjects with normal eyes and 6 eyes from 6 subjects with drusen secondary to AMD were scanned. The 3- × 3-mm scans resulted in higher repeatability than the 6- × 6-mm scans. For the Phansalkar method, larger values of the radius resulted in higher repeatability. ANOVA tests resulted in significant differences (P < 0.001) among the FCM method and the Phansalkar method with different radius options for all CC metrics and scan sizes investigated. In 3- × 3-mm scans, significant correlation was found between the FCM method and the Phansalkar method for all quantitative CC metrics other than FDN (all P < 0.001; 0.90 < r <0.99). CONCLUSIONS Quantitative CC analysis with commercially available OCTA is complicated and researchers need to pay close attention to how they conduct such analyses.
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Affiliation(s)
- Zhongdi Chu
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Giovanni Gregori
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Philip J Rosenfeld
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, Washington; Department of Ophthalmology, University of Washington, Seattle, Washington.
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