Optical coherence tomography angiography (OCTA) is a new, non-invasive imaging technique that generates volumetric angiography images in a matter of seconds. This is a nascent technology with a potential wide applicability for retinal vascular disease. At present, level 1 evidence of the technology’s clinical applications doesn’t exist. In this paper, we introduce the technology, review the available English language publications regarding OCTA, and compare it with the current angiographic gold standards, fluorescein angiography (FA) and indocyanine green angiography (ICGA). Finally we summarize its potential application to retinal vascular diseases. OCTA is quick and non-invasive, and provides volumetric data with the clinical capability of specifically localizing and delineating pathology along with the ability to show both structural and blood flow information in tandem. Its current limitations include a relatively small field of view, inability to show leakage, and proclivity for image artifact due to patient movement/blinking. Published studies hint at OCTA’s potential efficacy in the evaluation of common ophthalmologic diseases such age related macular degeneration (AMD), diabetic retinopathy, artery and vein occlusions, and glaucoma. OCTA can detect changes in choroidal blood vessel flow and can elucidate the presence of choroidal neovascularization (CNV) in a variety of conditions but especially in AMD. It provides a highly detailed view of the retinal vasculature, which allows for accurate delineation of the foveal avascular zone (FAZ) in diabetic eyes and detection of subtle microvascular abnormalities in diabetic and vascular occlusive eyes. Optic disc perfusion in glaucomatous eyes is notable as well on OCTA. Further studies are needed to more definitively determine OCTA’s utility in the clinical setting and to establish if this technology may offer a non-invasive option of visualizing the retinal vasculature in detail.
... Optical coherence tomography angiography (OCT-A) is a relatively new imaging technique, and it provides detailed and high-resolution imaging of the retina and choriocapillaris [14][15][16]. OCT-A technology has been described in detail before [14]. Briefly, visualization of the retinal and choriocapillary blood vessels is achieved through the detection of signal differences caused by the movement of blood cells in the otherwise static tissue through multiple, high-resolution scans of a specific area [14,17,18]. ...
... In contrast to dye-based methods, like FLA and ICG, OCT-A can be performed in cases of dye intolerance, severe renal insufficiency, or pregnancy [14,23]. OCT-A enables the precise visualization and quantification of retinal perfusion and of the foveal avascular zone (FAZ) with good intra-device and intra-personal reproducibility [14][15][16]. Using appropriate software, the automated quantification of the retinal microcirculation is possible. ...
Background/Objectives: This study aims to investigate the long-term effect of inactive systemic lupus erythematosus (SLE) on the retinal microcirculation measured via optical coherence tomography angiography (OCT-A). Methods: Twenty-four eyes of 24 patients with inactive SLE under hydroxychloroquine (HCQ) therapy were included. The OCT-A data (mainly vessel density (VD) and foveal avascular zone (FAZ) data of the superficial and of the deep capillary plexus (SCP, DCP) and the choriocapillaris (CC)) were analyzed and compared between the baseline examination (t0) and 2 years later (t1). Results: At t1, VD in the whole en face SCP and in the CC was notably reduced compared to t0 (SCP: p = 0.001, CC: p = 0.013). VD in the DCP, CRT and FAZ area showed no difference at t1 compared to t0 (DCP: p = 0.128, FAZ: p = 0.332, CRT fovea: p = 0.296). Correlation analysis between the increase in cumulative doses of HCQ between t0 and t1 and the VD of the whole en face SCP did not show any correlation (Spearman r = 0.062 (95% CI −0.367; 0.477). Conclusions: SLE patients demonstrated a decrease in the retinal VD of the SCP and CC over a 2-year period. There was no correlation with the change in cumulative doses of HCQ. These results suggest an ongoing effect of the disease on the retinal and choriocapillary microcirculation.
... Optical coherence tomography angiography (OCTA) is a new imaging technique based on OCT. OCTA uses motion-contrast imaging to obtain high-resolution information on volumetric blood flow, thus generating angiographic images without the use of dye in a matter of seconds (53). A recent study has shown the potential of OCTA in stroke monitoring by examining retinal microvascular parameters, revealing marked rarefaction of the retinal capillaries in both the macular and optic disc vascular plexus in patients with stroke (54). ...
Stroke is a primary cause of noncommunicable disease-related death and disability worldwide. The most common form, ischemic stroke, is increasing in incidence resulting in a significant burden on patients and society. Urgent action is thus needed to address preventable risk factors and improve treatment methods. This review examines emerging technologies used in the management of ischemic stroke, including neuroimaging, regenerative medicine, biology, and nanomedicine, highlighting their benefits, clinical applications, and limitations. Additionally, we suggest strategies for technological development for the prevention, diagnosis, and treatment of ischemic stroke.
... 33,34 Specifically, in terms of microvasculature imaging, optical coherence tomography angiography (OCTA) was introduced and was extensively utilized in a diverse range of applications. 35,36 OCTA is specialized for vasculature imaging and does not require hardware modifications to conventional OCT systems. OCTA stands out for its ability to assess microvascular structures, offering a noninvasive, label-free, and depth-resolved portrayal of microvasculature with unparalleled capillary-level precision. ...
Novel hearable technology is securely and comfortably positioned within the ear canal minimizing inaccuracies caused by accessory movements during activities. Despite extensive research on hearable technologies within the outer ear, there is a lack of research in the field of vascular imaging and quantitative analysis in the outer ear in vivo, which is one of the crucial factors to select the appropriate sensor position. Therefore, in this paper, we introduced optical coherence tomography angiography (OCTA)-based qualitative and quantitative analyses to visualize the inner vasculature of the outer ear to acquire vascular maps for microvascular assessments in vivo. By generating maximum amplitude projection images from three-dimensional blood vascular volume, we identified variations of blood vessel signal caused by the different biological characteristics and curvature of the ear among individuals. The performance of micro-vascular mapping using the proposed method was validated through the comparison and analysis of individual vascular parameters using extracted 20 vascular-related variables. In addition, we extracted pulsatile blood flow signals, demonstrating its potential to provide photoplethysmographic signals and ear blood maps simultaneously. Therefore, our proposed OCTA-based method for ear vascular mapping successfully provides quantitative information about ear vasculature, which is potentially used for determining the position of system-on-chip sensors for health monitoring in hearable devices.
This cross-sectional optical coherence tomography angiography (OCTA) study aimed to assess the macular and optic nerve head (ONH) vascular density, foveal avascular zone, and outer retina and choriocapillaris flow in oligoarticular juvenile idiopathic arthritis (oJIA).
Prospective.
Twenty-two eyes of 22 oJIA patients with uveitis (oJIA-U), 20 eyes of 20 oJIA patients without uveitis (isolated oJIA), and 26 healthy volunteers of similar ages and sexes were investigated. The superficial capillary plexus (SCP) and deep capillary plexus (DCP), ONH, foveal avascular zone (FAZ) parameters, the flow area of the outer retina, and choriocapillaris were evaluated.
Compared with the control group, both the oJIA-U group and isolated oJIA group showed significantly decreased vessel density of parafovea (p = 0.031 and p = 0.047, respectively) in DCP. Choriocapillaris flow area at 1 mm radius was significantly lower in the oJIA-U group compared to the control group (p = 0.001). Choriocapillaris flow area at 2- and 3-mm radius were significantly lower in the oJIA-U group compared to the control group (p < 0.001, for both) and isolated oJIA-U group compared to the control group (p = 0.008 and p = 0.001, respectively). The VD and thickness parameters of SCP and ONH, FAZ, and outer retina flow area were similar between the groups.
oJIA patients with and without uveitis revealed a decreased vessel density in the deep parafoveal region and choriocapillaris flow. Our findings suggest that retinal choroidal microvascular changes could be evident in oJIA-U patients without posterior segment involvement as well as oJIA patients without uveitis.
This study compares the effectiveness of Conbercept and Aflibercept in treating neovascular age-related macular degeneration (nAMD). Conducted at the First Affiliated Hospital of Chongqing Medical University's Ophthalmology Department (May 2020–May 2023), this prospective study enrolled 159 nAMD patients. Participants were randomly divided into two groups: one receiving 0.5 mg Conbercept and the other 2 mg Aflibercept intravitreal injections. Over 12 months, the study, employing a Treat-and-Extend (T&E) regimen, assessed Best-Corrected Visual Acuity (BCVA), Central Retinal Thickness (CRT) changes and injection frequency. Of the 159 patients, 137 (149 eyes) completed the study. No significant age difference was found between the groups (P = 0.331). After 12 months, BCVA improved similarly in both groups (Conbercept: 52.8 ± 18.9, Aflibercept: 52.0 ± 19.7 letters; P = 0.820). CRT reduction was also comparable (Conbercept: 246.3 ± 82.8 µm, Aflibercept: 275.9 ± 114.3 µm; P = 0.079). Injection frequencies averaged 6.9 ± 0.7 (Conbercept) and 6.7 ± 0.7 (Aflibercept; P = 0.255). Subtype analysis revealed Type 1 MNV had higher baseline BCVA and lower CRT, with more frequent injections compared to other types. Both Conbercept and Aflibercept are clinically similar in efficacy for nAMD, with the T&E regimen proving therapeutically effective and potentially reducing patient costs. Anti-VEGF treatment efficacy varies across nAMD subtypes, indicating a potential benefit in tailored treatments for specific subtypes.
Clinical trial registration number NCT05539235 (Protocol Registration and Results System).
We propose a new simple and cost-effective optical imaging technique, full-field amplitude speckle decorrelation angiography (FASDA), that can be implemented with cameras with conventional frame rates, does not require raster scanning, and is capable of classifying vessels into superficial and deep. The proposed imaging technique is based on the simultaneous evaluation of two metrics: the blood flow index, a contrast-based metric used in laser speckle contrast imaging, and the adaptive speckle decorrelation index (ASDI), a new metric that we defined based on the second-order autocorrelation function that considers the limited speckle modulation that occurs in partially-coherent imaging. We demonstrate excellent delineation of superficial vessels in skin nevi using ASDI and deeper vessels using BFI, providing a powerful new tool for the imaging of microvasculature with significantly lower hardware complexity than other optical imaging techniques.
To investigate the potential of ultrahigh-speed swept-source optical coherence tomography angiography (OCTA) to visualize retinal and choroidal vascular changes in patients with exudative age-related macular degeneration (AMD).
Observational, prospective cross-sectional study. An ultrahigh-speed swept-source prototype was used to perform OCTA of the retinal and choriocapillaris microvasculature in 63 eyes of 32 healthy controls and 19 eyes of 15 patients with exudative AMD.
qualitative comparison of the retinal and choriocapillaris microvasculature in the two groups.
Choroidal neovascularization (CNV) was clearly visualized in 16 of the 19 eyes with exudative AMD, located above regions of severe choriocapillaris alteration. In 14 of these eyes, the CNV lesions were surrounded by regions of choriocapillaris alteration.
OCTA may offer noninvasive monitoring of the retinal and choriocapillaris microvasculature in patients with CNV, which may assist in diagnosis and monitoring. [Ophthalmic Surg Lasers Imaging Retina. 2014;45:496-505.].
Copyright 2014, SLACK Incorporated.
Purpose:
To evaluate eyes with age-related macular degeneration and high-risk characteristics for choroidal neovascularization (CNV) with optical coherence tomographic (OCT) angiography to determine whether earlier detection of CNV is possible.
Methods:
Eyes with drusen, pigmentary changes, and with CNV in the fellow eye were scanned with a 70-kHz spectral domain OCT system (Optovue RTVue-XR Avanti). The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was used to distinguish blood flow from static tissue. Two masked graders reviewed scans for CNV, defined as flow in the outer retinal/sub-RPE slab. Choroidal neovascularization flow area repeatability and between-grader reproducibility were calculated.
Results:
Of 32 eyes, 2 (6%) were found to have Type 1 CNV with OCT angiography. The lesions were not associated with leakage on fluorescein angiography or fluid on OCT. One case was followed for 8 months without treatment, and the CNV flow area enlarged slightly without fluid buildup on OCT or vision loss. Between-grader reproducibility of the CNV flow area was 9.4% (coefficient of variation) and within-visit repeatability was 5.2% (pooled coefficient of variation).
Conclusion:
Optical coherence tomographic angiography can detect the presence of nonexudative CNV, lesions difficult to identify with fluorescein angiography and OCT. Further study is needed to understand the significance and natural history of these lesions.
This report describes a new system for digital indocyanine green videoangiography (ICGV) that provides enhanced imaging of the choroidal circulation. This newly assembled system was used to study a consecutive series of 129 patients with exudative age-related macular degeneration (AMD), and ill-defined or occult choroidal neovascularization (CNV). Overall, 39% of the patients in this study with occult CNV could be reclassified as having well-delineated or so-called classic CNV by virtue of the additional findings provided by ICGV. In this series, ICGV was particularly useful in identifying occult CNV in eyes with a large, serous pigment epithelial detachment (PED) and in eyes with recurrent CNV after previous laser photocoagulation treatment. Some of these patients were selected for laser photocoagulation of the abnormal choroidal vessels in order to evaluate the feasibility of this form of treatment on the basis of combined clinical, fluorescein angiographic, and ICGV findings. The results of this study suggest that ICGV is an important adjunct in the evaluation, classification, and laser treatment of patients with occult CNV secondary to AMD.
To noninvasively evaluate the retinal microvasculature in healthy human subjects with optical coherence tomography angiography (OCTA).
Cross-sectional, observational study of five healthy subjects. OCTA was performed on 3 × 3 mm(2) sections centered on the fovea, nasal macula, and temporal macula. Retinal vasculature was assessed within three horizontal slabs consisting of the inner, middle, and outer retina. The vasculature within each retinal slab was reconstructed using phase-based and intensity contrast-based algorithms and visualized as separate en face images.
OCTA in healthy subjects demonstrates capillary networks consistent with previous histological studies. No retinal vessels were found in the outer retina. OCT angiography of the inner and middle retinal layers showed region-specific vascular patterns that consistently corroborated qualitative findings from past histological studies.
OCTA generates high-resolution, noninvasive angiograms qualitatively similar to conventional fluorescein angiography. OCTA may serve as a bridge to assess some features of the retinal microvasculature between conventionally performed angiograms. [Ophthalmic Surg Lasers Imaging Retina. 2014;45:510-515.].
Copyright 2014, SLACK Incorporated.
Importance
The retinal vasculature is involved in many ocular diseases that cause visual loss. Although fluorescein angiography is the criterion standard for evaluating the retina vasculature, it has risks of adverse effects and known defects in imaging all the layers of the retinal vasculature. Optical coherence tomography (OCT) angiography can image vessels based on flow characteristics and may provide improved information.Objective
To investigate the ability of OCT angiography to image the vascular layers within the retina compared with conventional fluorescein angiography.Design, Setting, and Participants
In this study, performed from March 14, 2014, through June 24, 2014, a total of 5 consecutive, overlapping B-scan OCT angiography images composed of 216 A-scans were obtained at 216 discrete positions within a region of interest, typically a 2 × 2-mm area of the retina. The flow imaging was based on split-spectrum amplitude decorrelation angiography (SSADA), which can dissect layers of vessels in the retina. These distinct layers were compared with the fluorescein angiograms in 12 healthy eyes from patients at a private practice retina clinic to evaluate the ability to visualize the radial peripapillary capillary network. The proportion of the inner vs outer retinal vascular layers was estimated by 3 masked readers and compared with conventional fluorescein angiograms of the same eyes.Main Outcomes and Measures
Outcome measures were visualization of the radial peripapillary capillary network in the fluorescein and SSADA scans and the proportion of the inner retinal vascular plexus vs the outer retinal capillary plexus as seen in SSADA scans that would match the fluorescein angiogram.Results
In none of the 12 eyes could the radial peripapillary capillary network be visualized completely around the nerve head by fluorescein angiography, whereas the network was readily visualized in the SSADA scans. The fluorescein angiograms were matched, with a mean proportion of the inner vascular plexus being 95.3% (95% CI, 92.2%-97.8%) vs 4.7% (95% CI, 2.6%-5.7%) for the outer capillary plexus from the SSADA scans.Conclusions and Relevance
Fluorescein angiography does not image the radial peripapillary or the deep capillary networks well. However, OCT angiography can image all layers of the retinal vasculature without dye injection. Therefore, OCT angiography, and the findings generated, have the potential to affect clinical evaluation of the retina in healthy patients and patients with disease.
